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    Spatial-Temporal Variation of Cultivated Land Soil Basic Productivity for Main Food Crops in China
    LI YuHao,WANG HongYe,CUI ZhenLing,YING Hao,QU XiaoLin,ZHANG JunDa,WANG XinYu
    Scientia Agricultura Sinica    2022, 55 (20): 3960-3969.   DOI: 10.3864/j.issn.0578-1752.2022.20.008
    Abstract416)   HTML52)    PDF (473KB)(230)       Save

    【Objective】 Soil basic productivity is the cornerstone of realizing high and stable yield for food crops. The temporal change trends and spatial variation characteristics of cultivated land productivity for main food crops were defined, so as to provide the important theoretical support for ensuring food security and improve cultivated land quality in China. 【Method】 In this study, based on the national long-term positioning monitoring network of cultivated land quality from 1988 to 2019, the long-term monitoring data of the check area were selected with non-fertilization treatment and the conventional area with farmers' fertilization treatment in the first 3-5 years since the establishment of each monitoring point. The temporal and spatial changes in yield of maize, rice and wheat and soil productivity contribution rates were analyzed in China. 【Result】 In the past 30 years, the grain crops’ yield and soil productivity contribution rates showed an overall increasing trend with time, and the annual growth rate of crop yield showed the change law of non-fertilizer area < conventional area, rice < wheat < maize. The yield of maize, wheat and rice in the non-fertilizer area increased from 2 370, 1 712 and 3 111 kg·hm-2 in 1988 to 4 852, 3 258 and 4 167 kg·hm-2 in 2019, respectively, and increased by 104.7%, 90.2% and 34.0%, respectively. The yield of maize, wheat and rice in the conventional area increased from 5 356, 3 296 and 5 970 kg·hm-2 in 1988 to 8 859, 6 515 and 7 825 kg·hm-2 in 2019, respectively, with the increment of 65.4%, 97.6% and 31.0%, respectively. The contribution rate of soil productivity for the three major food crops in China from 2015 to 2019 was 52.7%, which was significantly increased by 7.3% compared with 45.4% in 1988-1994. Among them, the contribution rate from maize was 54.3%, which was 12.2% higher than that of 42.1% in 1988-1994. The contribution rate from rice was 53.3%, which was 6.7% higher than that of 46.6% in 1988-1994. The soil productivity contribution rate from wheat increased with the year as a whole, and was lower than that in maize and rice as a whole. The spatial distribution of soil productivity contribution rate for the three major grain crops was quite different. The Northeast region and Yellow River and Huaihai region were higher, which were 56.5% and 54.1%, respectively, followed by the Southwest region and South region, which were 53.7% and 52.9%, respectively. Gan Xin region and Qinghai-Tibet region were the lowest, only 38.7% and 40.4%, respectively. The random forest model was used to rank the soil factors affecting the basic soil productivity contribution rate in the three major grain crop systems. Among them, soil available potassium, organic matter content and soil bulk density were the key factors affecting the spatial distribution of maize basic soil fertility contribution rate; soil available phosphorus, available potassium and organic matter content were the key factors affecting the spatial distribution of wheat basic soil fertility contribution rate; soil pH, soil available phosphorus and organic matter content were the key factors affecting the spatial distribution of rice basic soil fertility contribution rate.【Conclusion】 Over the past 30 years, the soil basic productivity for three major grain crops in China has been continuously improved, but there were great differences among regions and the overall level was still low, which was far lower than that of developed countries in Europe and United States. Soil available potassium content, soil available phosphorus content and soil pH are the most key factors affecting the spatial distribution of basic soil fertility contribution rate of maize, wheat and rice, respectively.

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    Preparation and Properties of Bionic Modified Water-Based Polymer Coated Urea
    CHEN ChunYu,CHEN SongLing,HAN YanYu,REN LiJun,ZOU HongTao,ZHANG YunLong
    Scientia Agricultura Sinica    2022, 55 (20): 3970-3982.   DOI: 10.3864/j.issn.0578-1752.2022.20.009
    Abstract215)   HTML37)    PDF (2334KB)(86)       Save

    【Objective】The water-based polymer material is widely used in slow-release fertilizers due to its degradability, non-toxicity and good film-forming properties, but due to its poor water resistance, resulting in poor slow-release effect of the prepared coated fertilizer. In order to improve its water resistance ability, according to the principle of bionics, the nano silica and 1H,1H,2H,2H-perfluorodecyltrimethoxysilane were used for hydrophobic modification, the optimal modification ratio and mechanism were determined, and then the environmentally friendly coated urea with better slow-release effect was prepared. 【Method】 This experiment used a three-factor three-level L9 (33) orthogonal design to explore the content of chitosan (0.5%, 1.0%, and 1.5%), starch content (0.5%, 1.0%, and 1.5%) and polyvinyl alcohol (PVA) content ( 2%, 3%, and 4%) on the performance of water-based polymer films, the optimal ratio with better hydrophobic effect was screened through water absorption and range analysis. Furthermore, 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, and 3.0% of nano silica was add to the preferred coating materials for hydrophobic modification, respectively. The optimal amount of nano silica was confirmed by measuring the water absorption and permeability of the nano-modified water-based polymer films. Subsequently, the preferred nano-modified water-based polymer film was placed in the nhexane solution containing 0.5%, 1.0%, 1.5%, and 2.0% 1H,1H,2H,2H-perfluorodecyltrimethoxysilane for self-assembly modification, and then the effect of assembly concentration on the properties of films was explored. The modification effect was clarified by the changes of the film's hydrophobicity and permeability, and the hydrophobic modification mechanism was explored through the infrared spectrum characteristics and surface microstructure changes of the films before and after modification. The nutrient release experiments in soil were conducted to explore the nutrient release characters of the biomimetic modified water-based copolymer coated urea. The results of the nutrient release experiments in soil were used to investigate the sustained nutrient release period of nano-modified and biomimetic modified water-based copolymer-coated urea.【Result】 When the content of chitosan was 0.5%, the content of starch was 1.5%, and the content of PVA was 4.0%, the water absorption of the prepared water-based polymer film was the lowest, which was 42.50%. Compared with water-based polymers, the water absorption rates of nano-silica modified water-based copolymer, nano-silica and FAS dual-modified water-based copolymer membrane materials were reduced by 38.54% and 55.98%, respectively, the water permeability were reduced by 36.14% and 60.98%, respectively, and the NH4+ permeability were reduced by 24.14% and 44.58%, respectively. Infrared spectroscopy results showed that the amount of -OH in the nano-silica modified water-based copolymer membrane material was reduced, and Si-O-Si swing vibration and anti-symmetric stretching vibration were observed. The water after the double modification of nano-silica and FAS C-F bonds were observed on the surface of the base copolymer material. The scanning electron microscopy and energy spectrum analysis results showed that Si element appeared on the surface of nano-silica modified water-based copolymer membrane material, and F element appeared on the surface of nano-silica and FAS dual-modified water-based copolymer membrane material and observed a rough surface structure, the water contact angles were increased from 62.5º to 118.6º, and then the coating material could slow down the release effect. In addition, the results of soil culture experiments showed that the control release period of nutrients for nano-silica modified water-based copolymer-coated urea (NWCU), nano-silica and FAS dual-modified water-based copolymer-coated urea (SNWCU) was significantly prolonged. The control release period of nano-silica and FAS dual-modified water-based copolymer-coated urea was increased to about 28 days compared with those of WCU about 10 days. 【Conclusion】 According to the principle of biomimetics, the combined modification with nano-silica and FAS could significantly improve the water resistance and permeability of water-based polymer films, which the prepared biomimetic modified water-based copolymer coated nitrogen fertilizer had a good slow-release effect.

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    Influence of Plastic Film on Agricultural Production and Its Pollution Control
    ZHANG JinRui,REN SiYang,DAI JiZhao,DING Fan,XIAO MouLiang,LIU XueJun,YAN ChangRong,GE TiDa,WANG JingKuan,LIU Qin,WANG Kai,ZHANG FuSuo
    Scientia Agricultura Sinica    2022, 55 (20): 3983-3996.   DOI: 10.3864/j.issn.0578-1752.2022.20.010
    Abstract465)   HTML57)    PDF (553KB)(340)       Save

    Plastic film has been widely used in the farmland all over the world especially in arid and semi-arid areas because of its remarkable agricultural benefits, such as increasing soil temperature and moisture, reducing weed and pest damage, extending crop-growing areas, and consequently improving crop yield and quality. However, the degradation rate of plastic film is extremely slow, and the recovery of plastic film is also relatively backward in China, which lead to a large number of plastic debris in the farmland, causing plastic residues and microplastics pollution in the soil environment. Based on literature, investigation and statistical data, this research reviewed and prospects the impact of plastic film on agricultural production and pollution control in China. Plastic residues and microplastics have been reported to change the physical and chemical properties of soil, restrict soil water and nutrient transport, do harm to the growth, development and reproduction of soil animals and plants, change the abundance and community structure of soil microorganisms, and damage the soil health. In the long-term, plastic residues and microplastics pollution will cause a decline in crop yield and quality. Microplastics had the potential to be absorbed by plants, enter the human body through the food chain and pose a threat to human health. In addition, the large specific surface area of microplastics enabled them to become carriers of other pollutants (e.g. heavy metals, pesticides and antibiotics), causing combined pollution to the soil ecological environment. The standard of plastic film production and use in China was gradually being improved, however, there was still a certain gap compared with developed countries and regions. In addition, a sustainable recycling system of plastic film and the policy of preventing plastic residue and microplastics pollution have not been well formed in China, and the study of microplastics pollution in Chinese farmland soil was still very limited. Therefore, it is critical to solve the problem of plastic residues and microplastics pollution in the soil by evaluating the present situation of plastic residues and microplastics pollution in soils, quantifying the effects of microplastics on the soil environment, and evaluating risks of microplastics to the soil ecosystems, as well as exploring the measures of controlling soil plastic residues and microplastics pollution, and formulating relevant policies and regulations of preventing these pollution.

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    The Variation Characteristics of Soil Organic Carbon Component Content Under Nitrogen Reduction and Film Mulching
    WANG ChuHan,LIU Fei,GAO JianYong,ZHANG HuiFang,XIE YingHe,CAO HanBing,XIE JunYu
    Scientia Agricultura Sinica    2022, 55 (19): 3779-3790.   DOI: 10.3864/j.issn.0578-1752.2022.19.008
    Abstract259)   HTML44)    PDF (584KB)(147)       Save

    【Objective】 The aim of this study was to clarify the effects of long-term optimized fertilization (nitrogen reduction) and nitrogen reduction plus film mulching on the characteristics of soil organic carbon (SOC) and its components content, and their contribution to winter wheat grain yield, so as to provide the theoretical support for dryland fertility and crop productivity in the Loess Plateau. 【Method】 Based on a 7-year location experiment, the undisturbed soil samples from 0-20 cm under different management measures were collected. The variation characteristics of winter wheat grain yield, SOC and its components content were explored, including particulate organic carbon (POC), mineral organic carbon (MOC), light-particulate organic carbon (Light-POC) and heavy-particulate organic carbon (Heavy-POC), and the relationship between SOC and its component content as well as their quantity contribution to the winter wheat grain yield were clarified. The organic carbon components were grouped by continuous physical grouping method, and their contribution for wheat yield was analyzed by redundancy analysis. The experiment set four treatments, including farmer’s practice fertilization (FP), monitoring fertilization (MF), monitoring fertilization plus ridge mulching-furrow planting (RF), and monitoring fertilization plus whole field filming (FH). 【Result】 The average yield of winter wheat was the lowest under FP treatment, which was 3 070 kg·hm-2. Compared with FP, the wheat yield under MF showed no significant difference, while wheat grain yield under RF and FH could achieve a significant increase by 27.0% and 46.4%, respectively; compared with the initial year of the experiment (2012), the SOC content showed a significant increase under different management measures during seven consecutive years, and the increase rate from low to high was 11.8% (MF), 22.4% (RF), 25.5% (FP), and 36.1% (FH), respectively. The improvement of SOC under MF was the slowest in calcareous cinnamon soil, when MF combining with plastic film mulching showed a significant improvement. The observed SOC components under different treatments showed, compared with FP and MF, RF and FH significantly increased the content of POC, Light-POC and the proportion of Light-POC in SOC. Based on the cooperation of the redundancy analysis, sensitivity index analysis and correlation analysis between SOC and its component, POC contributed the most to the improvement of wheat yield (up to 71.0%) and was the most sensitive to SOC content change and different management measures. Therefore, the improvement of crop yield and soil fertility by FH was mainly achieved by increasing POC content in soil organic carbon. 【Conclusion】 The monitoring fertilization plus whole field filming treatment was benefit to increase soil organic carbon and active organic carbon content in the cinnamon soil in the southeastern of the Loess Plateau, and achieve a sustainable increase in winter wheat yield.

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    Effects of Reduced Phosphorus Application on Crop Yield and Grain Nutritional Quality in the Rice-Wheat Rotation System in Chaohu Lake Basin
    ZHANG XinYao,ZHANG Min,ZHU YuanPeng,HUI XiaoLi,CHAI RuShan,GAO HongJian,LUO LaiChao
    Scientia Agricultura Sinica    2022, 55 (19): 3791-3806.   DOI: 10.3864/j.issn.0578-1752.2022.19.009
    Abstract298)   HTML42)    PDF (579KB)(102)       Save

    【Objective】 The aim of this study was to explore the effects of reduced phosphorus (P) application on crop yield and nutritional quality, so as to provide a theoretical basis for increasing the P use efficiency and producing high grain quality of crops under the rice-wheat crop rotation system in the Chaohu Lake Basin. 【Method】 A field trial of reduced P application rates was conducted from 2017 to 2019 with five treatments in the Chaohu Lake Basin, which were contrast (CK, No phosphorus), farmers’ application rate (P1, 90 kg P2O5·hm-2), 10% P reduction (P2, 81 kg P2O5·hm-2), 20% P reduction (P3, 72 kg P2O5·hm-2), and 30% P reduction (P4, 63 kg P2O5·hm-2). The effects of reduced P application rates on rice and wheat grain yield and its components, grain protein and fraction content, micronutrients and their bioavailability were analyzed. 【Result】 Compared with no P application, the P application significantly increased the grain yield of rice and wheat by 9.8% to 28.3% and 56.6% to 89.7%, respectively. The 10% and 20% P reduction treatments for rice and wheat grain yield were not significantly different from the farmers’ P fertilizer application (P>0.05). However, the rice yields under the 30% P reduction treatment were significantly decreased by 14.4%. Compared with the farmers’ P application rate, the P reduction treatments significantly affected the crop protein, gliadin and glutenin content, while which had no significant effect on structural protein (albumin and globulin); the P reduction of 20% reduced rice grain protein and glutenin content by 2.7% and 32.3%, respectively. Compared with farmers’ P application rate, the grain protein and glutenin content of rice and wheat under the 30% phosphorus reduction treatment reduced by 6.8% and 21.9%, 48.4% and 31.6%, respectively. Phosphorus application also significantly affected the micronutrients content and bioavailability in rice and wheat grains. Compared with the farmers’ P application rate, P reduction treatments increased iron (Fe), copper (Cu) and zinc (Zn) concentration in rice and wheat grains by 21.2% and 19.3%, 11.9% and 15.8%, 14.5% and 19.9%, respectively; meanwhile, P/Fe, P/Cu and P/Zn molar ratios also reduced by 21.6% and 26.3%, 20.6% and 27%, 17.7% and 21.3%, respectively. The grain zinc concentration of rice and wheat increased linearly with decreasing P application, while the iron, manganese (Mn) and Cu concentrations were no significant differences among the P reduction treatments. P/Zn molar ratio of rice reduced with lower P application, but the P/Fe, P/Mn and P/Cu molar ratios had no significant differences among P reduction treatments. The P/Fe, P/Mn, P/Cu and P/Zn molar ratios in wheat grains reduced with lower P application, and then increasing the bioavailability of Fe, Cu and Zn in wheat grains. 【Conclusion】 In the rice-wheat crop rotation area of the Chaohu Lake Basin, reduced P application by 20% (from 90 kg P2O5·hm-2 reduction to 72 kg P2O5·hm-2) could still ensure stable crop yields. The reduced application of P fertilizer significantly increased the micronutrients concentration and its bioavailability in rice and wheat grains, although the grain protein and glutenin content lower than the farmers’ P application rate. In conclusion, the P3 (20% reduction in P fertilizer application based on the farmers’ P application rate) was the recommended P fertilizer rate to achieve P use efficiency and double high (yield and quality) of crop production in the rice-wheat rotation areas of the Chaohu Lake Basin.

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    Overview of Soil Survey Works in Main Countries of World
    WeiLi ZHANG,H KOLBE,RenLian ZHANG,DingXiang ZHANG,ZhanGuo BAI,Jing ZHANG,HuaDing SHI
    Scientia Agricultura Sinica    2022, 55 (18): 3565-3583.   DOI: 10.3864/j.issn.0578-1752.2022.18.008
    Abstract360)   HTML38)    PDF (549KB)(242)       Save

    The reviewing soil surveys and soil investigations in different countries shows that in order to understand the soil resources and soil quality, the soil surveys and investigations carried out by different countries since the end of the 19th century can be divided into four categories, namely: survey for soil classification, investigation and evaluation of farmland fertility, testing of soil chemical properties for fertilizer recommendation and soil investigations related to environmental issues. Among the four categories, soil classification is the earliest and the most widely implemented survey works carried out in the world. Main purpose of the classification survey is to clarify the differences in soil types and their spatial distributions caused by various soil formation processes. Since soil formation processes under natural conditions can reach tens of thousands of years, the main outputs of the classification survey—the soil maps and the records of soil profiles, expressing the physicochemical properties of various soil types, have a long timeliness and are widely used in various research areas. After the completion of nation-wide soil classification surveys in the last century in developed countries, the updated survey was not conducted in these countries. In the second national soil survey in China, large-scale soil maps covering the whole country were completed by relatively higher profile sampling density. The physicochemical properties of 100 000 soil profiles, representing different soil types, were also recorded. Both the map scale and the richness of soil profile data from the survey surpassed the outputs from classification surveys in many developed country. Soil classification data obtained from this survey are valid for a long time to different disciplines and sectors. In order to meet needs for easy-to-understand farmland fertility grades by land management sectors and farmers, investigation and evaluation of farmland fertility have been carried out in Central European countries, where per capita arable land resources have been in shortage. Through high-density profile samplings, soil fertility evaluation for each farmland plot with an independent cadastral code was carried out. An officially certified fertility grades in percentile index and the records of soil profiles were established and archived for each plot. The investigation results have been widely used in farmland management, taxation, agricultural subsidies, farmland leasing, trading, lending, insurance and other sectors, and have become the indispensable and centennial basic information for farmland quality. China's per capita arable land is much less than that of Central European countries, but so far there has been still in shortage of soil fertility data for farmland management. For preservation of arable land resources with high fertility and ensure food safety, it is essential and also urgent to establish precise and reliable fertility archives for each farmland plot in China. Also more efficient investigation and evaluation approaches, which are compatible with China's economic and social condition should be developed. The review of testing soil chemical properties to make fertilizer recommendation shows that such testing has been incorporated into the technical supporting system for best farming management practices in the developed countries. To improve farmers' fertilization techniques, it is more important to establish an efficient technical supporting system and maintain its running, in comparison to nation-wide soil nutrient census of farmland. In the past, there was continuous weakening of applied researches and extension works for fertilization technological chain from basic research to farmers' application. Due to inadequate research works, the technical indexes for fertilization, that should be differentiated to and compatible with the various regional soil and climate conditions and hence easy to be followed by farmers of different regions, have not been issued yet in China. Also the intelligent tools that can reach and provide targeted guidance to farmers were not available. Unbalanced and excessive fertilization was common in vegetable, fruit and other cash crop growing area, which accounted for 23.6% of the total cropping area in China. This resulted in reduction of crop yield and quality as well as benefit of farmers and also leaded to agricultural non-point source pollution. Making up for the shortcomings in the technical supporting system has become the key to improve both crop yield and soil fertility. Since the end of the last century, soil investigations related with environment issues have been carried out in different countries. Main purposes of these investigations are to clarify the status of environmental pollution and changing, to develop control strategy and to check effects of countermeasures. With the quick progresses of GIS-, GPD-, RS- and big data techniques, the traditional mapping approaches have be replaced by digital soil mapping techniques. An exact defining of investigation objectives and a comprehensive reviewing of relevant research progress as well as available auxiliary data are essential for drafting sampling design and achieving investigation tasks finally.

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    Research Progress of Direct Straw Return in Anhui Province over the Last Decade
    Chao MA,YuBao WANG,Gang WU,Hong WANG,JianFei WANG,Lin ZHU,JiaJia LI,XiaoJing MA,RuShan CHAI
    Scientia Agricultura Sinica    2022, 55 (18): 3584-3599.   DOI: 10.3864/j.issn.0578-1752.2022.18.009
    Abstract384)   HTML43)    PDF (3456KB)(201)       Save

    The returning straw directly to the field is the most widely adopted approach of straw utilization. Anhui is an important agricultural province with abundant main grain crop straw resources. In recent years, the direct straw return was actively promoted and a series of relative research were conducted in Anhui Province. In order to provide reference for the development of more in-depth research and promote the efficient utilization of straw resources, the recent important advances in straw direct returning technology and the effects of straw incorporation on soil fertility, crop production and agricultural eco-environment in Anhui Province were reviewed in this paper. The research progress of direct straw return in Anhui Province over the last decade were mainly embodied in the following aspects. (1) The technology of straw direct returning was optimized from manner of straw returning and combined application of chemical fertilizers. (2) The introduction of chemical structure of soil organic matter and soil microbial community structure broadened the research field concerning the effects of direct straw return on soil physical, chemical and biological properties. (3) The impact of straw incorporation on crop diseases, insect pests and weeds was beginning to be explored, and the increasingly attention was being paid to the environmental effects of straw return on nitrogen and phosphorus loss and greenhouse gas emission. Therefore, it could be concluded that the research on direct straw return in Anhui Province presented the transformation from a focus on crop production to more attention on eco-environmental effects. In the future, the study on straw directly returning to the field in Anhui Province should be strengthened from the following aspects: improving regional weak links, expanding research contents, clarifying environmental effects, and deepening mechanism exploration.

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    Effect of Nitrification on Ammonium Toxicity to Citrus in Acidic Soil
    ZiHan FAN,YaYin LUO,HuaYe XIONG,YuWen ZHANG,FuRong KANG,YuHeng WANG,Jie WANG,XiaoJun SHI,YueQiang ZHANG
    Scientia Agricultura Sinica    2022, 55 (18): 3600-3612.   DOI: 10.3864/j.issn.0578-1752.2022.18.010
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    【Objective】The response process of citrus to NH4+-N was elaborated by observing the impact of NH4+-N level on different pH soil solutions, combined with a study on the impact of orange rootstock seedling growth and physiological indicators, which provided theoretical support for the best citrus nitrogen management in acid soil. 【Method】 The experiment was designed as a two-factor experiment, with 2 soils as the main treatment and 5 N levels as the secondary treatment. Using acidic yellow soil and alkaline purple soil as the test soil, the seedlings of Xiangcheng (junos Sieb. ex Tanaka) were selected as the test material, and five NH4+-N levels of 0 (A0), 50 (A50), 100 (A100), 200 (A200), and 400 mg·kg-1 (A400) were set. The effects of ammonium application level on the concentration of ammonium nitrogen and nitrate nitrogen in soil solution and on the biomass, root morphology, nitrogen absorption, antioxidant system, nitrogen metabolism, MDA content and root activity of citrus were studied. 【Result】 Compared with calcareous soil, the nitrification process in acid soil was slowed down. The NH4+-N concentration and NH4+/ NO3- ratio in the soil solution of acid soil remained at a higher level at 30 days of the test. The root length of the citrus under A400 treatment was reduced by 13% when compared with the A0 treatment, and the root vitality was significantly negatively correlated with the ammonium application level. The MDA content of leaves and roots was positively correlated with the ammonium level, which stimulated the oxidative stress response of the roots, especially increased the POD enzyme activity of the leaves. Compared with calcareous soil, the total nitrogen accumulation of citrus on acid soil decreased by 17.6%, while the ratio of ammonium to nitrate in leaves and roots increased by 27.2% and 61.1%, respectively. Cluster analysis showed that citrus in acidic soil was toxic when N application rate exceeded 100 mg kg-1, while citrus in alkaline soil was not significantly stressed.【Conclusion】 In acidic soil, the excessive application of ammonium nitrogen caused the accumulation of ammonium nitrogen in soil solution for a long time, resulting in the increase of MDA content, cell membrane damage and nitrogen metabolism disorders as well as other ammonium toxic phenomena, indicating that ammonium toxicity in citrus was closely related to soil nitrification.

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    Conversion Characteristics of Different Carboxyl-Containing Organic Acids Modified Urea in Calcareous Fluvo-Aquic Soil
    ZHANG YingQiang,ZHANG ShuiQin,LI YanTing,ZHAO BingQiang,YUAN Liang
    Scientia Agricultura Sinica    2022, 55 (17): 3355-3364.   DOI: 10.3864/j.issn.0578-1752.2022.17.008
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    【Objective】 The conversion characteristics of different carboxyl-containing organic acids modified urea combined with carboxyl groups and other active functional groups in calcareous fluvo-aquic soil were investigated, so as to provide a theoretical basis for the development of high-efficiency nitrogen fertilizers.【Method】 The citric acid (carboxyl group + hydroxyl group), humic acid (carboxyl group + phenolic hydroxyl group/carbonyl group/aldehyde group, etc.), polyglutamic acid (carboxyl group + amino group) and polyacrylic acid (carboxyl group) were added into the molten urea at 0.5% addition amount, to prepare the test fertilizers, exactly, citric acid urea (CAU), humic acid urea (HAU), polyglutamic acid urea (PGAU) and polyacrylic acid urea (PAAU). The treatments of without urea (CK), common urea (U), CAU, HAU, PGAU and PAAU were set up to study the effects of different carboxyl-containing organic acids modified urea on the soil amide nitrogen, NH4+-N, NO3--N and soil urease activity by using soil incubation method. The influence mechanism of different carboxy-containing organic acids modified urea in soil conversion was revealed with the results from Fourier transform infrared spectroscopy (FTIR) of U and different carboxy-containing organic acids modified urea.【Result】 (1) Compared with U, the four kinds of carboxyl-containing organic acids modified urea delayed the urea hydrolysis in the soil from 6 h to 2 d. HAU and PGAU had a better performance than other treatments, and their residual amount of soil urea nitrogen increased by 22.3% and 23.7% than that with U, respectively. (2) Compared with the appearing time of NH4+-N content peak treat with U (2 d), HAU application delayed to the appearing time of NH4+-N content peak to the third day. In 6 h-2 d, the average value of NH4+-N content with HAU treatment decreased by 16.9% than that with U, while increased by 3.2% in 3-14 d. (3) Compared with U, four kinds of carboxyl-containing organic acids modified urea significantly increased soil NO3--N content in the later period of incubation, and the HAU treatment showed the highest value with an average increase of 17.4 mg·kg-1 than the U treatment. (4) Compared with U, four kinds of carboxyl-containing organic acids modified urea inhibited soil urease activity in 1-2 d, among which HAU had the strongest inhibitory effect, and the urease activity was reduced by 30.9% compared with U. However, HAU enhanced the soil urease activity in 2-14 d.【Conclusion】 Carboxyl-containing organic acids modified urea could delay the hydrolysis and transformation of urea in the soil by inhibiting urease activity in the early stage of incubation delaying the transformation of NH4+-N to NO3--N in the middle stage of incubation, and increase the NO3--N content of cultivated soil in the late stage of incubation to reduce nitrogen loss. The above results were mainly attributed to the reaction of carboxyl groups and other active functional groups with urea. The reaction degree with urea was the deepest when the carboxyl group and a variety of active functional groups (phenolic hydroxyl group/aldehyde group/carbonyl group) existed at the same time, which attributed the slow release of urea to the best.

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    Research on Soybean Irrigation Schedule Based on AquaCrop Model
    WANG QiaoJuan,HE Hong,LI Liang,ZHANG Chao,CAI HuanJie
    Scientia Agricultura Sinica    2022, 55 (17): 3365-3379.   DOI: 10.3864/j.issn.0578-1752.2022.17.009
    Abstract269)   HTML24)    PDF (686KB)(119)       Save

    【Objective】 The aim of this study was to evaluate the applicability of AquaCrop model in the Guanzhong Plain and to explore the optimal irrigation schedule for summer soybean under various precipitation year types. 【Method】 AquaCrop model was calibrated by using field experiment data and then used to simulate soybean yield and water use efficiency under 14 irrigation systems with three different precipitation years from 1961 to 2019.【Result】 The determination coefficient (R2), root mean square error (RMSE), standard root mean square error (NRMSE) and Nash efficiency coefficient (EF) of simulated and measured soybean yield under the highest yield treatment by AquaCrop model were 0.96, 7.15%, 11.03% and 0.94, respectively, which of simulated and measured biomass values were 0.99, 526.04 kg·hm-2, 14.45% and 0.97, respectively. A good agreement was observed for final yield simulation with the R2, RMSE, NRMSE, and EF were 0.97, 49.98 kg·hm-2, 1.74% and 0.82, respectively. The R2 values of the measured and simulated canopy coverage and biomass of each treatment were greater than 0.95, indicating that the AquaCrop model could better simulate the growth and development dynamics and yield of soybean in Guanzhong Plain. Combined with the simulation results of the model, the water requirements of the whole growth period of soybean were 398.2 mm. The water requirements of each growth period were significantly different for three precipitation years. The water requirements in the soybean branch stage were 127.8 mm, the water requirements of flowering and podding stage were 212.6 mm, and those of grain filling stage were 57.7 mm. Combined with the simulation of different irrigation systems for three different precipitation years, it was found that the flowering and podding period stage was the key period of water demand, and the water supply in this growth period affected the final yield of soybean. Simulation resulted showed that no irrigation was needed in wet years. In the normal and dry years, it was recommended to irrigate only 45 mm and 70 mm at flowering and podding stage to achieve the maximum yield of 2 699 kg·hm-2 and 2 486 kg·hm-2, and the maximum water use efficiency of 0.74 kg·m-3 and 0.7 kg·m-3, respectively. 【Conclusion】 To ensure higher soybean yield and water use efficiency, the soybean irrigation schedule in this region should be determined based on the distribution of different precipitation years, which could be used as a reference for the soybean irrigation system in the Guanzhong Plain region.

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    Thought of Pollution Comprehensive Prevention and Control System of Non-Point Sources Based on National Food Security
    YANG ShiQi
    Scientia Agricultura Sinica    2022, 55 (17): 3380-3394.   DOI: 10.3864/j.issn.0578-1752.2022.17.010
    Abstract274)   HTML39)    PDF (658KB)(166)       Save

    【Objective】 In this study, in view of food security (FS) in China, the situation of non-point source pollution (NPS) was clearly showed, and NPS technical system and NPS comprehensive prevention and control system were proposed. 【Method】 The grain production and fertilizer application among main nations were compared, including total grain output and fertilizer application, per capita grain and per hectare fertilizer application, ration of fertilizer application and grain productive capacity. Meanwhile, the ration of nitrogen fertilizer and it’s judgment and ration of nitrogen fertilizer based on provincial scale were analyzed, and NPS reduction effects according to two national pollution censuses, trends of NPS reduction in China were deeply investigated, including total amounts and it’s proportion, NPS reduction potential (stockbreeding, plantation, nitrogen reduction and food saving). Based on FS the NPS technical system was constructed, and NPS comprehensive prevention and control system was proposed. 【Result】 (1) The per capita grain was more than 400 kg in 2008, more than 450.0 kg in 2012 and 475.0 kg in 2019 in China, indicating a higher FS created a key safeguard for NPS. (2) The ration of nitrogen application was not high and decreased on national scale, which was 161.1 kg·hm-2 in 2019 and lay low side of reasonable range. The excessive and inadequate application should be paid attention. (3) At the national scale, the ration of nitrogen fertilizer application 160.0-170.0 kg·hm-2 could safeguard per capita grain 450.0-500.0 kg in the future. (4) NPS reduction scheme: firstly, the dung should be all returned to field, and the pollutant emission should be close to zero, and the Ⅴ class water from NPS should be basically eliminated. Secondly, TN and TP emission from plantation should be reduced to 4.0×105-4.5×105 t and 4.0×104-5.0×104 t, respectively. Thirdly, the saving food and decreasing food waste could create the favorable condition for field fertilizer, emission and stress reduction, rehabilitation and FS. The key elements of NPS technical system based on FS were suitable fertilizer application, soil conservation and crop production, and a good and harmonious system should set up by agricultural machinery, farmland irrigation and water conservancy, clean stockbreeding, intelligence techniques, standards, laws and regulations to form farming system with local and watershed characters, then which had an extensive application. 【Conclusion】 NPS comprehensive prevention and control system was composed of scientists, agricultural producers and government to form the trinity, which should motivate scientist initiative, agricultural producer enthusiasm and government functions to carry out the double security of national food and environment in China in the future.

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    Response of Wheat Yield and Grain Nitrogen, Phosphorus and Potassium Concentrations to Test-Integrated Potassium Application and Soil Available Potassium in Northern Wheat Production Regions of China
    MA Yue,TIAN Yi,MU WenYan,ZHANG XueMei,ZHANG LuLu,YU Jie,LI YongHua,WANG HaoLin,HE Gang,SHI Mei,WANG ZhaoHui,QIU WeiHong
    Scientia Agricultura Sinica    2022, 55 (16): 3155-3169.   DOI: 10.3864/j.issn.0578-1752.2022.16.008
    Abstract302)   HTML45)    PDF (575KB)(225)       Save

    【Objective】It is of great importance to clarify the relationships of changes in wheat grain yield and grain nutrients absorption and distribution to test-integrated potassium (K) fertilizer application and soil available K, for the purpose of high yield, high quality, green production of wheat and saving K resources in northern wheat production region of China. 【Method】In this research, a 43-site field experiment was conducted in northern wheat region of China from 2018 to 2020, to investigate effects of test-integrated K application on grain yield, yield components, grain nitrogen (N), phosphorus (P), and K concentrations, and nutrients uptake and absorption of wheat at different soil available K levels. 【Result】The insufficient and excessive K application occurred widely in northern wheat production region. With the increase of soil available K level, the wheat yield increased significantly and reached the maximum value of 6 340 kg·hm-2 at the available K of 150-180 mg·kg-1. Excessive soil available K was not able to further increase the grain yield, and it significantly decreased to 5 409 kg·hm-2 when soil available K was higher than 180 mg·kg-1. Compared with the farmers’ fertilizer application rate (FF), the recommended K fertilizer rate (RF) by the test-integrated fertilizer application was decreased at the soil available K level of 150-180 mg·kg-1, and increased at the other levels. The RF was found to have increased the wheat yield in comparison to FF with the yield increase significant at soil available K lower than 90 mg·kg-1 and higher than 180 mg·kg-1. When the soil available P was higher than 30 mg·kg-1 and the soil available K was at 120-150 mg·kg-1 or higher than 180 mg·kg-1, the wheat yield of no K application (RF-K) showed a tendency to decrease in comparison to RF. With the increase of soil available K level, wheat grain N concentration increased significantly, but no significant difference was observed in the grain N, P, and K concentrations between FF and RF. Compared with RF, the grain N, P, and K concentrations under RF-K significantly decreased when the soil available K was higher than 180 mg·kg-1. When the soil available K was higher than 180 mg·kg-1, the K partial factor productivity and K fertilizer uptake efficiency under RF were significantly higher than those under FF. 【Conclusion】The reasonable fertilization could get high wheat yield when the soil available K was at 150-180 mg·kg-1, but the wheat yield might be reduced without K fertilization when the soil available P was higher than 30 mg·kg-1. Therefore, the K fertilizer rate should be recommended based on the target wheat yield and soil available P and K levels, for the purpose of yield stabilization, quality improvement, and efficiency increase in the northern wheat production regions of China.

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    Temporal and Spatial Characteristics of Resources Input and Environmental Effects for Maize Production in the Three Provinces of Northeast China
    CHEN XuHao,GAO Qiang,CHEN XinPing,ZHANG WuShuai
    Scientia Agricultura Sinica    2022, 55 (16): 3170-3184.   DOI: 10.3864/j.issn.0578-1752.2022.16.009
    Abstract299)   HTML43)    PDF (541KB)(208)       Save

    【Objective】The total production of maize is the highest among the three staple grain crops in China, ranking second position in the world. The planting area of maize in the three provinces of northeast China accounts for 39% of China, while the investment of resources is relatively low. The purpose of this study is to clarify the temporal and spatial characteristics of resources input and environmental effects for maize production in the three provinces of northeast China. 【Method】 In this paper, based on the life cycle assessment (LCA) method, the reactive nitrogen loss model suitable for maize production in the three provinces of northeast China was used to quantitatively evaluate the resources input (fertilizer, pesticide and diesel oil, etc.) and related environmental risks such as reactive nitrogen losses and GHG emissions of maize production systems in Northeast China from 2007 to 2016. 【Result】The average total fertilizer application rate of maize production in Jilin Province was 400 kg·hm-2, the average yield per unit area was 7 065 kg·hm-2, the average GHG emissions per unit area was 2 965 kg CO2 eq·hm-2, all of the above were the highest in the three provinces, but the carbon and nitrogen footprint was low, and the average reactive N losses per unit area was in the middle level and changed little from year to year. The average nitrogen input of Liaoning Province was 184 kg·hm-2, the average N loss per unit area was 20.8 kg N·hm-2, and carbon and nitrogen footprint was 493 kg CO2 eq·Mg-1 and 3.53 kg N·Mg-1, respectively, all of which were the highest. The per unit yield of 5 966 kg·hm-2, was in the middle level, and the GHG emission did not change much from year to year. The average nitrogen application rate in Heilongjiang Province was 149 kg·hm-2 per unit yield, the average unit area N losses and GHG emissions were the lowest in the three provinces, while the carbon and nitrogen footprint were in the middle level. From 2008 to 2015, the planting area of maize in the three provinces of northeast China increased year by year, with a cumulative increase of 5.73 million hectares. In 2015, the total maize production of the three provinces was the highest, reaching 91.16 million tons, accounting for 32% of the country's ten-year (2007-2016) average production, of which Heilongjiang Province, Jilin Province and Liaoning Province accounted for 13.9%, 11.7%, and 6.7%, respectively. The ten-year average planting area accounted for 30% of the country, of which Heilongjiang Province, Jilin Province and Liaoning Province accounted for 14.7%, 9.3%, and 6.4%, respectively. The ten-year average maize grain yield in the three provinces of northeast China was 6 116 kg·hm-2, and the highest average yield was achieved in 2013, which was 6 824 kg·hm-2. During 2007 to 2016, the fertilizer input of maize production in the three provinces of northeast China showed an overall upward trend, nitrogen fertilizer decreased steadily, while phosphorus and potassium fertilizer increased year by year. From 2014 to 2016, the increase trend of fertilizers rate slowed down sharply and gradually became stable. The ten-year average rate of nitrogen, phosphate and potassium fertilizers were 177, 101, and 70.2 kg·hm-2, respectively. From 2007 to 2016, the pesticide input for maize production in Northeast China showed a steady upward trend, while the diesel input was relatively stable in the first four years, and then gradually increased. During the ten years of maize production in Northeast China, the average rate of pesticide used was 10.2 kg·hm-2, and that of diesel was 94.6 kg·hm-2. The average N losses and GHG emissions per unit area of maize production in 2007-2016 were 19.0 kg N·hm-2 and 2 770 kg CO2 eq·hm-2, respectively. The reactive nitrogen losses per unit area was stable from 2007 to 2016. The average GHG emissions of maize production showed a downward trend in 2007-2008 and 2009-2011, a steady upward trend in 2012-2016, and reached the highest with 3 045 kg CO2 eq·hm-2 in 2016. Ammonia volatilization caused by field application of nitrogen fertilizer was the main way of reactive nitrogen losses in maize production, followed by nitrate leaching loss, and nitrous oxide emission. The main emission sector of GHG emissions was fertilizer production, transportation and field application. During the past ten years, the average nitrogen footprint and carbon footprint of maize production in Northeast China were 3.16 kg N·Mg-1 and 459 kg CO2 eq·Mg-1, respectively. 【Conclusion】The resource inputs and environmental cost of maize production in the three provinces of northeast China were significantly different on the spatial scale. The average fertilizer input of Jilin Province was 124 kg·hm-2 higher than that of Heilongjiang Province, while the GHG emissions were 524 kg CO2 eq·hm-2 higher. In 2007-2016, the nitrogen input for maize production in the three provinces of northeast China ranged from 170 to182 kg·hm-2, N losses ranged from 18.4 to19.4 kg N·hm-2, which played a good demonstration role for the green development of agriculture in China. The carbon and nitrogen footprint of maize production mainly depended on the trade-off between resource input and yield per unit area, noticeably, the nitrogen fertilizer input had a greater impact. The spatial-temporal characteristics analysis of resource inputs and environmental effects for maize production in the three provinces of northeast China contributes to clarify the limiting factors and main controlling factors at present stage, and provides theoretical support for optimizing nutrient management to achieve win-win situation of food security and carbon emission reduction.

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    Effects of Amendments on Soil Fauna Community Characteristics in a Fluvo-Aquic Sandy Soil
    YANG Jing,ZHANG He,LI ShuangShuang,LI GuiHua,ZHANG JianFeng
    Scientia Agricultura Sinica    2022, 55 (16): 3185-3199.   DOI: 10.3864/j.issn.0578-1752.2022.16.010
    Abstract246)   HTML52)    PDF (693KB)(130)       Save

    【Objective】 Soil fauna is an important component of terrestrial ecosystem, therefore, the studying of the relationship between soil fauna and amendments will help reveal the mechanism of amendments to soil fauna.【Method】During 2016-2019, the characteristics of the soil fauna community in the soil surface layer (0-20 cm) of wheat and maize rotation area with different amendments were investigated. There were four treatments, including no amendment (CK), organic amendment 15 t·hm-2 (YJ), inorganic amendment 2.25 t·hm-2 (WJ) and organic amendment 15 t·hm-2+inorganic amendment 2.25 t·hm-2 (YW). 【Result】During the study period, 4 351 soil fauna belonging to 8 classes, 20 orders, 41 families, and 44 classes were collected, of which 28 families were macrofauna, and the dominant groups were Asilidae and Myrmicinae, accounting for 62.9% of the total captured soil macrofauna. In another, 14 families soil meso-and micro-fauna were collected, and the dominant groups were Acarid and Oribatida, accounting for 93.0% of the total captured soil meso- and micro-fauna. Soil fauna mainly belonged to saprozoic and omnivores. The data indicated that the total number and taxa of soil fauna collected during the experiment was the highest under WJ, and the lowest under YJ. The number of Scutigerellidae, Sejidae and Japygidae decreased and their richness index decreased, while the mites increased, and the dominance index was high under amendments comparing with CK. There were significant differences in individual number and diversity index of small and medium animal communities among different years (P<0.05), and the number of individuals showed a gradually increasing trend; but the Jaccard index (q) of soil fauna was less than 0.50 among all treatments, and the similarity of macrofauna community was lower than that of meso- and micro- community. The ecological niche widths of meso- and micro- soil fauna, such as Acarid, Oribatida, and Onychiuridae, were higher than those of macrofauna, such as Myrmicinae. However, the niche overlap index was higher than 0.97, indicating that the application of amendments increased the common resources of soil fauna. The NMDS analysis showed that the soil animal community in wheat season 2018 was significantly different from that in other years, whereas, in maize season of 2016, 2018, and 2019, there were different. The results of RDA indicated that soil TN and AK were significantly correlated with Acarid, Oribatida, Onychiuridae, Enicocephalidae, Carabidaein wheat season (P<0.05); the soil organic matter and pH were main factors influencing Acarid, Enicocephalidae, Sciaridae, and Asilidae in maize season (P<0.05). The PRC analysis showed that the relative abundance of Uropodidae peaked in October 2017, and that of Asilidae and Myrmicinae peaked in October 2016 under YJ. The relative abundance of Onychiuridae, Acarid, and Oribatida reached a peak in October 2016 under the combined application of organic and inorganic amendments, and that of Phlaeothripidae and Enicocephalidae appeared in 2019 and peaked in October 2019, demonstrating the incongruity of soil fauna groups to the amendments. 【Conclusion】The variation of soil fauna community and diversity in different years were much more profound than amendments, and the amendments modified soil fauna community and diversity mainly by changing soil pH, SOM, and TN in a fluvo-aquic sandy soil.

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    Geostatistical Characteristics of Soil Data from National Soil Survey Works in China
    ZHANG WeiLi,FU BoJie,XU AiGuo,YANG Peng,CHEN Tao,ZHANG RenLian,SHI Zhou,WU WenBin,LI JianBing,JI HongJie,LIU Feng,LEI QiuLiang,LI ZhaoJun,FENG Yao,LI YanLi,XU YongBing,PEI Wei
    Scientia Agricultura Sinica    2022, 55 (13): 2572-2583.   DOI: 10.3864/j.issn.0578-1752.2022.13.008
    Abstract410)   HTML52)    PDF (2252KB)(206)       Save

    【Objective】China carried out the second state soil survey from 1979 to 1987 and the soil nutrient investigation of farmland from 2005 to 2017. Both surveys covered the whole country with a huge amount of ground soil samplings. The data generated from the two surveys have become the most detailed spatial-temporal data for soil types and quality in China. The purpose of the study was to test and to evaluate the geostatistical characteristics of the data by geostatistical testing approach, so as to provide the reference for the use of these data to characterize the temporal and spatial distribution of soil features in different disciplines. 【Method】7 testing areas were selected to represent different regions in China. Soil organic matter (SOM) contents of 0-20 cm soil layer from soil profile sampled in 1979-1987 and from plough layer sampled in 2005-2017 were extracted from the corresponding data bases. The ground sampling for soil profiles in 1979-1987 was to give priority to typical soil types firstly and secondly to keep an evenly distributed sampling as possible. 100 000 soil profiles with about 1m soil deep were finally sampled. After integrated data processing and coordinate matching, 60 000 profiles obtained coordinates. Ground sampling for soil plough layer in 2005-2017 was in grid distribution. 10 000 000 plough layer soil samples with GPS positioning coordinates have been completed. For each testing area, the data set contained two groups, about 500-1 300 SOM values from soil profile data and 50 000-250 000 values from plough layer data. The data from two time groups of each testing data set were analyzed by ordinary Kriging approach separately. 80% of the data were randomly selected as the training sample set for modeling and 20% as the verification sample set. The linear regression between the predicted value and the measured value of the validation sample was carried out. R2 (coefficient of determination) and RMSE (root mean square error) were calculated to evaluate the reliability and uncertainty of the data sets in expressing the spatial distribution of the soil feature. 【Result】It was showed that the reliability of mapping SOM content by profile data of all of the 7 testing areas reached significant levels. However, the deviation between predicted values and measured values of the test data set was relatively great. The values of R2 were low, between 0.223-0.380 and RMSE were relatively high. Testing results by soil plough layer data sampled in 2005-2017 showed that through large sample size and grid sampling, the reliability and prediction accuracy of mapping SOM content were improved greatly, for R2 increased and RMSE decreased. The geostatistical test results of two periods with a time interval of 30 years showed that although there were some changes in the contents of soil organic matter, the overall spatial distribution of SOM content in each testing area expressed by the two data groups was similar. 【Conclusion】 The reliability and accuracy of soil maps were much better in terms of characterizing the spatial distribution of soil features, when the soil investigation was by means of a large sample size with grid sampling. It meant that the reliability and accuracy of the original large-scale soil thematic maps, such as maps of soil types, organic matter, pH value, soil nitrogen, phosphorus and potassium nutrient contents from second state soil survey, were better than maps generated by profile data, as these original large-scale soil thematic maps were derived from the large sample size with grid sampling. However, the data of 60 000 soil profiles from second state soil survey, which contained many soil features and could supply reliable soil thematic maps, were also of great importance for understanding spatial characteristics of these soil features. It has been showed that a large sample size was essential for a precise and accurate mapping of soil feature of the whole country. For mapping long-term changing or stable soil features such as soil types, texture and morphological features, it would be difficult to obtain reliable maps by a soil sample size much less than the second state soil survey. Considering the current requirements and the available data resources in China, the soil investigation in the future could be mainly focused in investigating data missing areas as well as some missing soil features for soil functions.

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    Current Status of Chemical Fertilizers, Pesticides, and Irrigation Water and Their Reducing Potentials in Wheat Production of Northern China
    WEI Lei,MI XiaoTian,SUN LiQian,LI ZhaoMin,SHI Mei,HE Gang,WANG ZhaoHui
    Scientia Agricultura Sinica    2022, 55 (13): 2584-2597.   DOI: 10.3864/j.issn.0578-1752.2022.13.009
    Abstract348)   HTML37)    PDF (1672KB)(224)       Save

    【Objective】The unreasonable use of chemicals and irrigation water is the crucial to limiting the wheat production. The objective of the study was to clarify the current status of chemical fertilizers, pesticides, and irrigation water in wheat production of Northern China and their reduction potentials. Further, understanding the effects of farm size on wheat production could provide an effective reference for sustainable wheat production in China. 【Method】 Based on a large-scale survey in seven provinces of Northern China during 2018-2019, based on the nutrient requirements formed by wheat yield, the potential of fertilizer reduction in northern wheat regions and the potential of pesticide reduction based on the recommended amount of pesticides were assessed, and the water-saving potential based on Penman-Monteith was estimated, and then the effects of farm size on wheat yield and the input costs of chemical fertilizer and irrigation water were investigated. 【Result】The mean wheat yields of spring wheat area, Fenwei Plain, Loess Plateau, and oasis irrigation area were 3.0, 7.6, 4.7, and 7.4 t·hm-2, respectively. The application rate of nitrogen (N), phosphorus (P) and potassium (K) fertilizer was 87 kg N·hm-2, 91 kg P2O5·hm-2, and 1 kg K2O·hm-2 in spring wheat area, was 280 kg N·hm-2, 133 kg P2O5·hm-2, and 1 kg K2O·hm-2 in Fenwei Plain, was 178 kg N·hm-2, 117 kg P2O5·hm-2, and 25 kg K2O·hm-2 in Loess Plateau, and was 225 kg N·hm-2, 168 kg P2O5·hm-2, and 15 kg K2O·hm-2 in oasis irrigation area, respectively. The problems of excessive application of N and P fertilizers and insufficient application of K fertilizers coexisted. The reduction potential of N and P fertilizers was 25% and 40% in Fenwei Plain, respectively, which was 24% and 57% in Loess Plateau, respectively. The reduction potential of P fertilizer was 65% and 54% in spring wheat area and oasis irrigation area, respectively. The use of pesticides varied greatly in different areas of wheat production. In the spring wheat area of Fenwei Plain, Loess Plateau, and oasis irrigation area, the mean number of pesticides sprayed were 1.8, 1.4, 1.6, and 1.6 times, respectively; the reduction potential of pesticides was 40%-70%, 54%-83%, 40%-65% and 50%-83%, respectively. Insecticides and herbicides were the main types of pesticides, and the frequency of insecticides application accounted for 73%, which was higher than that of herbicides. For insecticides, imidacloprid and triadimefon were more commonly used. For herbicides, tribenuron-methy, 2, 4-D butyl ester, and sodium dimethyl tetrachloride were more often used. The irrigation times of wheat production were 2-4 in most cases. For Fenwei Plain, the mean number of irrigations was 2.2 times, and the river water was the most key source of irrigation water. For oasis irrigation area, the mean number of irrigations was 3.5 times, and the well water was the most key source of irrigation water. The water-saving potential in Fenwei Plain and oasis irrigation area was 14% and 42%, respectively. Small-scale farm size was the most common way to manage farms, resulting in a serious fragmentation of farmland in each wheat area. Compared with small-scale farm size, the large-scale farm size increased wheat yields by 7%-36% with reducing input costs by 17%-19%. 【Conclusion】The study reported the current status of the wheat yield, chemical fertilizers, pesticides, and irrigation water in wheat production of Northern China, and found that their application rates varied greatly between farmers and production regions. This brought huge potential for the reduction of chemical fertilizers, pesticides, and irrigation water. Moreover, combined with farm size, it clarified that an appropriate increase in farm size could increase wheat yield while decreasing input costs, which could be essential for optimizing management scale in wheat region of north China.

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    Optimal Management of Phosphorus Fertilization Based on the Yield and Grain Manganese Concentration of Wheat
    WANG HaoLin,MA Yue,LI YongHua,LI Chao,ZHAO MingQin,YUAN AiJing,QIU WeiHong,HE Gang,SHI Mei,WANG ZhaoHui
    Scientia Agricultura Sinica    2022, 55 (9): 1800-1810.   DOI: 10.3864/j.issn.0578-1752.2022.09.009
    Abstract285)   HTML40)    PDF (1192KB)(133)       Save

    【Objective】To keep the manganese (Mn) nutritional balance of wheat grains and ensure the safety, yield and quality in wheat production region of eight provinces in Northern China, the changes of concentration and accumulation of Mn in wheat grains and grains yield at different levels of soil available phosphorus (P) and different treatments of P fertilization were investigated. 【Method】During 2018-2019, 34-site field experiments were conducted with three P treatments, including farmers’ fertilizer application (FF), recommended fertilizer application based on soil nitrate and P test (RF), and recommended fertilizer application without P (RF-P). The wheat yield, the concentration of Mn in wheat grain were tested, and the effects of P fertilization on wheat yield and the Mn concentration of grain at different levels of soil available P were studied. 【Result】In wheat production region of eight provinces in Northern China, the average wheat yield was 6 066 kg·hm-2, and the average concentration of Mn in grains was 42 mg·kg-1. Those test sites with concentration of Mn in grains less than 32 mg·kg-1 or higher than 44 mg·kg-1, accounted for 8.8% and 36.8%, respectively, which suggested that the problem of high concentration of Mn in grains should be paid attention to. With the increase of soil available P, both wheat yield and concentration of Mn in grains increased significantly. The wheat yield reached to the highest when the available P was in the range of 20-30 mg·kg-1, while the concentration of Mn in grains reached to the highest when the available P>40 mg·kg-1. P fertilizer was reduced with an average of 45.4% under the RF treatment. However, the wheat yields of RF and FF were 6 358 and 6 222 kg·hm-2, respectively, and the concentration of Mn in grains were 42.8 and 43.6 mg·kg-1, respectively, which showed no significant difference. At different levels of soil available P, RF could maintain a high wheat yield. When soil available P<10 mg·kg-1, RF-P reduced not only the concentration of Mn in grains, but also reduced the wheat yield, while RF only reduced the concentration of Mn in grains. RF did not reduce the concentration of Mn in grains under other levels of soil available P. In addition, the concentration of diethylene triamine pentaacetic acid-manganese (DTPA-Mn) in soil increased following the increasing of soil available P. Furthermore, the concentration of Mn in grains were positively correlated with the concentration of soil DTPA-Mn. 【Conclusion】In wheat production region of eight provinces in Northern China, the soil available P should be maintained in the range of 20-30 mg·kg-1 to achieve high wheat yield and suitable concentration of Mn in grains. The use of RF technology would not reduce the wheat yield. RF-P reduced the concentration of Mn in grains when the soil available P<10 mg·kg-1, but there was a risk of reducing the wheat yield.

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    Spatiotemporal Patterns in Nitrogen Response Efficiency of Aboveground Productivity Across China’s Grasslands
    HOU JiangJiang,WANG JinZhou,SUN Ping,ZHU WenYan,XU Jing,LU ChangAi
    Scientia Agricultura Sinica    2022, 55 (9): 1811-1821.   DOI: 10.3864/j.issn.0578-1752.2022.09.010
    Abstract223)   HTML28)    PDF (2911KB)(102)       Save

    【Objective】This study was to investigate the temporal and spatial patterns of nitrogen (N) limitation (indicated by N response efficiency) on aboveground productivity of China’s grasslands, which was important for the adoptive management and accurately simulating of ecosystem N cycling under global environmental change. 【Method】A meta-analysis was performed to investigate N response ratio (lnRR) and N response efficiency (lnRR/N, the ratio of lnRR to N addition rate) of aboveground productivity across China’s grasslands. All data (423 groups) were collected from in-situ N addition experiments published over 1980-2020. Linear, double-linear and multi-step regressions were explored to estimate the spatial and temporal dynamics of lnRR/N and its driving factors. 【Result】In general, lnRR increased with N addition rates and saturated at (21.1±5.5) g N·m-2·a-1 (mean±95%CI) with the maximum of 0.60±0.08. lnRR/N was, on average, 0.043±0.004, i.e., aboveground productivity could increase by (4.36±0.38) % per unit N addition (1 g N·m-2·a-1). lnRR/N also differed significantly among grassland types, N addition rates, experimental durations, and years. Over the past four decades, lnRR/N significantly decreased, with a much (1.5-1.7 times) faster rate in the warmer (MAT>4.5℃) and wetter (MAP>450 mm) climatic regions than that in the cooler (MAT≤4.5℃) and drier (MAP≤450 mm) climatic regions. Regression analyses revealed that the spatial variation of lnRR/N was mainly driving by annual precipitation and soil fertility (i.e., soil N content). In general, lnRR/N increased along with MAP and decreased with soil N content. However, the driving factors varied by climatic regions, with both MAP and soil N content in the wetter regions, MAP in the drier regions and MAT in the warmer regions. 【Conclusion】 The aboveground productivity in China’s grasslands was still limited by N, but the extent of N limitation or N response efficiency decreased over time, especially in those wetter and warmer climatic regions. To accurately predict the response of grassland ecosystem to the ongoing global environmental change, the studies should pay more attention to the spatial and temporal shifting in driving factors for plant productivity.

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    Effects of Grazing Disturbance on the Stoichiometry of Nitrogen and Phosphorus in Plant Organs of Leymus chinensis Meadow Steppe
    WANG Miao,ZHANG Yu,LI RuiQiang,XIN XiaoPing,ZHU XiaoYu,CAO Juan,ZHOU ZhongYi,YAN RuiRui
    Scientia Agricultura Sinica    2022, 55 (7): 1371-1384.   DOI: 10.3864/j.issn.0578-1752.2022.07.009
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    【Objective】Taking above-ground communities, stems and leaves as research objects, the effects of different grazing intensities on the contents of carbon (C), nitrogen (N) and phosphorus (P) elements and stoichiometric characteristics of plant components and plant communities were investigated, which provided a scientific basis for in-depth analysis of grassland ecosystem degradation process under grazing disturbance and promotion of adaptive management of grassland grazing. 【Method】Based on the long-term controlled grazing test platform of Leymus chinensis meadow grassland in Hulunbuir, the plant communities and plant samples of different components were collected. The contents of C, N and P were determined by elemental analysis method, and then the changes of C, N and P contents and the measurement ratio under different grazing intensities were analyzed. 【Result】With the increase of grazing intensity, the C content of plant stem, leaf and community showed a significant linear decrease, and the C content of heavy to extremely heavy grazing was significantly lower than that of no grazing (P<0.05). The N and P contents of the community were linearly increased, and the heavy to extremely grazing was significantly higher than that of no grazing (P<0.05). The stem-leaf ratio of C content was the lowest in moderate grazing (G0.46), while the stem-leaf ratio of N content was the highest in heavy grazing (G0.69), and the highest in P content (G0.34). The coefficients of variation of C content and N/P ratio in different plant organs were small, but the coefficients of variation of N and P contents were large. The variation coefficients of C content and N/P ratio of different components ranged from 4.01% to 5.74% and 2.84% to 8.54%, respectively. The variation coefficients of N and P contents of plants ranged from 11.47% to 14.96% and 11.13% to 22.88%, respectively, and the variation coefficients of C/N and C/P ratios ranged from 10.64% to 16.00% and 8.88% to 13.57%, respectively; among them, the coefficient of variation of the N/P ratio of plant leaves is the smallest, and the coefficient of variation of plant stem P content is the largest. The N/P ratio of leaves was between 14 and 16 under light grazing G0.34 and extremely heavy grazing G0.92, which was restricted by both N and P elements; while the other components were all lower than 14 under different grazing intensities, which was restricted by N. There was a significant negative correlation between grazing intensity and C content and C/N ratio of stem, leaf and community, and N/P ratio of stem and community, whilst they were significantly positively related to N content of stem, leaf and community, P content of plant leaf and community, and the N/P ratio of plant stem. The soil moisture was significantly positively correlated with the C content of plant leaves and community, the C/N ratio of stem, leaf and community, and the C/P ratio of stem and community, however, which were significantly negatively correlated the N content of stem, leaf and community and the P content of leaf and community. 【Conclusion】Grazing caused significant changes in plant C, N, P content, ecological stoichiometric ratio, and total community C, N, and P content. Overgrazing not only decreased the C content, C/N ratio and C/P ratio of plant stem, leaf and community, but also reduced the total C, N, and P content of the community, increased the N and P content of plant stem, leaf and community, and N/P ratio of plant stem, leaf and community. Moderate grazing decreased the C/N ratio of stem and leaf, and increased the C/P ratio and N/P ratio of stem and leaf, which was beneficial to promote the sustainable and stable development of grassland ecological functions.

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    Analysis to Evolution Characteristics of Policies for Controlling Agricultural Non-Point Source Pollution in China: Based on Text Quantification
    HUA ChunLin,ZHANG JiuHong,JIN ShuQin
    Scientia Agricultura Sinica    2022, 55 (7): 1385-1398.   DOI: 10.3864/j.issn.0578-1752.2022.07.010
    Abstract273)   HTML28)    PDF (542KB)(116)       Save

    【Objective】Based on the 365 agricultural non-point source pollution control policies promulgated by national departments from 1978 to 2018, the evolution characteristics of the policies were analyzed, and the administrative regulation, economic incentives and technical support measures of the policies were highlight to investigate. 【Method】 This paper used policy literature measurement and content analysis methods to quantify the text content of agricultural non-point source pollution control policy. 【Result】 The number of agricultural non-point source pollution policies was significantly less before 1992 in China. The period from 1993 to 2010 was the initial formation stage of agricultural non-point source pollution control policies, while the period from 2011 to 2018 was the deepening development stage of agricultural non-point source pollution control policies, the number of governance policies implemented has grown rapidly, and the number of policies implemented in 2017 reached 40. Agricultural non-point source pollution control policies were issued in the form of highly authoritative “laws” and “regulations” types of policy documents, as well as highly instructive “details” “interpretations” and “catalogs”. The issuers of agricultural non-point source pollution control policies included 31 entities, such as the “National People's Congress” “Ministry of Agriculture and Rural Affairs”, and “Ministry of Ecology and Environment”. There were 305 policies independently promulgated by policy issuers, and 60 policies jointly promulgated by various issuers. The individual citation of administrative regulatory measures accounted for 23.56% of the 365 policies, while the individual citations of technical support measures and economic incentive measures accounted for 8.22% and 6.03% of the 365 policies, respectively. Among the 365 policies from 1978 to 2018, the number of policies using three kinds of measures in coordination accounted for the highest proportion, which was 38.08%. The proportion of coordination between administrative regulation and technical support measures was 13.70%, while the proportion of coordination between administrative regulation and economic incentive measures was 6.85%. The proportion of economic incentive and technical support measures was 3.56%. In the 2011 policy document, 70.83% of the policies were combined with the three types of measures, compared with only 0 in 1978 and 33.33% in 2000. After 2000, the average value of administrative regulation measures effectiveness increased in a steady fluctuation, and the effectiveness value maintained between 2.5 and 3.5. The average effectiveness of economic incentive measures continued to fluctuate, and the upward trend was not obvious. In recent years, the effectiveness has declined, with the value of 3.2 in 2011 and 1.8 in 2018. The effectiveness of technical support measures has shown a significant upward trend at this stage, with the value of 3.2 in 2012 and 3.8 in 2018. 【Conclusion】 From 1978 to 2018, the number of agricultural non-point source pollution control policies in China has shown a trend of phased fluctuations; the form and issuers of policy were diversified. Among three measures in the policies, the administrative regulations were the most frequently used, while the economic incentives measures were the least. The overall effectiveness of policies showed a trend of rise while the average effectiveness was a smooth phase fluctuation. The average effectiveness of the three types measures in the policies all showed large fluctuations in the early stage. At this stage, in addition to economic incentive measures, both the effectiveness of administrative regulations and technical support measures are significant upward trend.

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    The Spatial Characteristics of Soil Organic Carbon Sequestration and N2O Emission with Long-Term Manure Fertilization Scenarios from Dry Land in North China Plain
    WANG ShuHui,TAO Wen,LIANG Shuo,ZHANG XuBo,SUN Nan,XU MingGang
    Scientia Agricultura Sinica    2022, 55 (6): 1159-1171.   DOI: 10.3864/j.issn.0578-1752.2022.06.009
    Abstract541)   HTML47)    PDF (3496KB)(268)       Save

    【Objective】To provide theoretical guidance for mitigating global warming, the comprehensive effects of manure amendment on soil organic carbon sequestration and greenhouse gas emissions were studied.【Method】Based on the long-term experiment, the validated process-based model-SPACSYS, combined with regional database and ArcGIS, was used to clarify the spatial characteristics of average annual soil organic carbon sequestration rate (SOCSR), average annual soil N2O emission and average annual net global warming potential (NGWP) under three long-term fertilization scenarios (equal nitrogen fertilization), namely, chemical fertilizers only (NPK), 50% of chemical fertilizers combined with 50% of manure (NPKM(5:5)) and 30% of chemical fertilizers combined with 70% of manure (NPKM(3:7)), from dry land in the North China Plain from 2010 to 2050.【Result】The SOCSR from dry land in the North China Plain was higher in the east and lower in the west, and the higher regions mainly included Jiangsu Province and Shandong Province. Correlation analysis showed that there was a significant negative correlation between SOCSR and initial soil organic carbon content. Stepwise linear regression analysis further indicated that initial soil organic carbon content, mean annual temperature and soil pH were three important factors affecting SOCSR, which accounted for 24% of the variation of SOCSR. The average annual soil N2O emission was higher in the central part of the North China Plain, lower in the north and south, and the higher regions included parts of Shandong Province and Jiangsu Province. Correlation analysis showed that there was a significant positive correlation between average annual soil N2O emission and initial soil organic carbon content. In general, compared with NPK, NPKM(5:5) and NPKM(3:7) both increased SOCSR and decreased average annual soil N2O emission from dry land in the North China Plain, of which SOCSR (233 and 236 kg C·hm-2·a-1) increased by 79% and 82%, respectively, the average annual soil N2O emission(15.8 and 14.4 kg N·hm-2·a-1) decreased by 21% and 28%, respectively. As a result, NGWP (6.6 and 5.9 t CO2-eq·hm-2·a-1) decreased by 26% and 34%, respectively.【Conclusion】Compared with the application of chemical fertilizers, the application of chemical fertilizers combined with manure was beneficial to SOC sequestration, soil N2O emission reduction and mitigation of glowing warming from dry land in the North China Plain over the long-term.

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    Characteristics of Efficient Nitrogen Uptake and Transport of Rapeseed at Seedling Stage
    CHAO ChengSheng,WANG YuQian,SHEN XinJie,DAI Jing,GU ChiMing,LI YinShui,XIE LiHua,HU XiaoJia,QIN Lu,LIAO Xing
    Scientia Agricultura Sinica    2022, 55 (6): 1172-1188.   DOI: 10.3864/j.issn.0578-1752.2022.06.010
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    【Objective】Nitrogen (N) uptake efficiency is one of the important factors affecting crop N efficiency, investigating characteristics of efficient N uptake and transport was the purpose to provide the theoretical basis for improving N efficiency and yield of rapeseed (Brassica napus L.) varieties.【Method】To explore the mechanisms underlying high N uptake and transport in rapeseed, two rapeseed germplasms with contrasting N efficiency (N efficient germplasm ‘498’ and N inefficient germplasm ‘428’) were used in this study under normal N (9.5 mmol·L-1) and low N (0.475 mmol·L-1) conditions at three different growth stages (Phenological growth stages 12, 14 and 16) in hydroponic culture. At the same time, the 15N isotope tracer technique was applied to study the uptake and transport capacity of NO3- and NH4+. Additionally, the expression level of genes (BnNPFs, BnNRT2s and BnAMTs)related to N uptake and transport in rapeseed germplasms with contrasting N efficiency were further analyzed by real-time quantitative PCR (RT-qPCR).【Result】Rapeseed germplasm ‘498’ showed superior advantages in plant growth and root development under different N concentrations, and the root morphological indexes (main root length, total root length, root surface area, root volume and lateral root number), biomass, N accumulation and N uptake efficiency were all significantly greater than those of germplasm ‘428’.15N isotope tracer test also showed that ‘498’ showed greater advantage in the uptake and accumulation of NO3 - and NH4+, especially for NH4+, as indicated by the significant differences in the accumulation of 15NH4+ between two germplasms. The RT-qPCR analysis further found that under normal N conditions, the relative expressions of BnNPF6.3a, BnNRT2.1e, BnNPF7.2a, BnNPF7.2c, BnNPF6.2c, BnAMT1;2a, BnAMT1;3c, BnAMT1;4a, BnAMT2;1a and BnAMT2;1b (involved in the uptake and transport of NO3 - and NH4+) was significantly higher in ‘498’ than that in ‘428’. While under low N stress, the relative expressions of BnNRT2.4a, BnNRT2.5a and BnNRT2.5b (involved in NO3 -uptake and transport) was significantly lower in the root of ‘498’ than that of ‘428’, but the expression level of BnNPF7.3a and BnNPF6.2c (referred to NO3 - transport and redistribution) was significantly higher in ‘498’ than that in ‘428’, as well as the expression level of BnAMT1;1a, BnAMT1;2a, BnAMT1;3c, BnAMT1;4a, BnAMT2;1a and BnAMT2;1b (involved in NH4 + uptake and transport).【Conclusion】Compared with N-inefficient germplasm ‘428’, N-efficient germplasm ‘498’ were superior in root length, root surface area (volume) and lateral root number, additionally with greater ability in N (especially NH4 +) uptake and accumulation. Under normal N application conditions, the expression of genes involved in NO3- and NH4+ absorption and transport were relatively higher in ‘498’, while the relative expression of genes involved in the NO3 - transport and redistribution as well as NH4+ absorption and transport were significantly higher in ‘498’ than that in ‘428’ under low N stress, illustrating the relative higher N uptake efficiency of ‘498’ possibly linked to the higher expressions of several BnNPFs sand BnAMTs.

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    Phosphorus Availability and Transformation of Inorganic Phosphorus Forms Under Different Organic Carbon Levels in a Tier Soil
    LU Peng,LI WenHai,NIU JinCan,BATBAYAR Javkhlan,ZHANG ShuLan,YANG XueYun
    Scientia Agricultura Sinica    2022, 55 (1): 111-122.   DOI: 10.3864/j.issn.0578-1752.2022.01.010
    Abstract533)   HTML38)    PDF (511KB)(193)       Save

    【Objective】 The influence of organic carbon on the contents and transformation of soil in organic phosphorus fractions were investigated, which can help to formulate soil managemental strategies whereby to improve phosphorus use efficiency in tier soil.【Method】 The soil samples were collected and selected with a gradient of organic carbon levels but similar in Olsen-P (ranges from 17.41 mg·kg-1to 18.72 mg·kg-1) under winter wheat summer maize cropping in the Guanzhong Plain of Shaanxi Province. The organic carbon contents of the selected soil samples were 6.38, 8.34, 10.17, 11.95, 13.64 and 15.74 g·kg-1, respectively. Then the soil inorganic phosphorus fractions (dicalcium phosphate (Ca2-P), octa-calcium phosphate (Ca8-P), apatite (Ca10-P), aluminum bounded phosphate (Al-P), iron bounded phosphate (Fe-P) and occluded phosphate (O-P)) were analyzed with the phosphorus fractionation procedure proposed by Chang & Jackson and modified by Jiang and Gu.【Result】 The results showed that organic carbon played an important role in transformation of soil inorganic phosphorus in the winter wheat-summer maize cropping in Guanzhong Plain of Shaanxi Province. The soil Ca2-P, Ca8-P, Al-P, Fe-P, O-P fractions, moderately labile P (Ca8-P, Al-P and Fe-P), and stable P (O-P and Ca10-P) pools were increased significantly and linearly with increasing soil organic carbon, whereas Ca10-P remained unchanged. The relative contents of labile-P (Ca2-P), moderately labile P (mainly Al-P) were significantly and positively correlated with SOC content, but stable P (mainly Ca10-P) showed significant negative correlation with SOC. Soil Olsen-P increased significantly and linearly with increasing stable P.【Conclusion】 Under the similar soil Olsen-P and total phosphorus conditions, soil organic carbon improved the availability of soil phosphorus mainly through promoting the conversion of stable P to moderately labile P and labile P in the soil, increasing the ratio of available phosphorus to inorganic phosphorus, and improving the availability of soil phosphorus. The results implied that improvement of soil fertility (SOC) could promote the activation and utilization of legacy phosphorus in soil.

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    Effects of Fertilization Methods on Ammonia Volatilization from Vegetable Field Under Greenhouse Cultivation
    WANG Cong,SUN HuiFeng,XU ChunHua,WANG ZhanFu,ZHANG JiNing,ZHANG XianXian,CHEN ChunHong,ZHOU Sheng
    Scientia Agricultura Sinica    2022, 55 (1): 123-133.   DOI: 10.3864/j.issn.0578-1752.2022.01.011
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    【Objective】 The massive ammonia (NH3) volatilization from excessive nitrogen (N) fertilization is a common issue in greenhouse cultivated vegetable production in China. To alleviate this problem, a field experiment was conducted to study the effects of different fertilization methods on NH3 volatilization of greenhouse vegetable fields.【Method】 The study was carried out with 6 fertilization treatments via one-time basal fertilization and two-time topdressings, including N fertilizer-blank treatment (Control), conventional fertilization treatment (CF), 20% N-reduced slow-release fertilizer treatment (SF), 20% N-reduced organic fertilizer treatment (OF), 20% N-reduced microbial fertilizer treatment (MF) and integrated management of water and fertilizer treatment (IM). Except for the Control treatment, an identical application ratio of N, P and K fertilizers was employed to each treatment throughout the whole vegetable growing season. The NH3 volatilization fluxes under different fertilization methods were observed by using venting absorption method. The potential influencing factors of NH3 volatilization were also investigated synchronously.【Result】 The dynamics of NH3 volatilization under different fertilization treatments were similar, and the occurrence of the peaks of NH3 flux was highly associated with fertilization time. During basal fertilization period, for the most of treatments, the NH3 fluxes peaks appeared 3-days after the application of basal fertilizer, while it was only 1-day under IM treatment. The maximum fluxes of NH3 ranged from 0.12 to 0.26 kg NH3·hm-2·h-1 during basal fertilization period. The occurrence of the peaks of NH3 fluxes were ahead by 1-2 days during topdressing periods. The maximum fluxes of NH3 volatilization were 0.08-0.19 kg NH3·hm-2·h-1 during the first topdressing period, and 0.13-0.18 kg NH3·hm-2·h-1 during second topdressing period. Significant differences were found among different fertilization treatments in the seasonal cumulative NH3 volatilizations. The seasonal cumulative NH3 volatilizations in the decreasing order of different treatments were CF, MF, OF, SF, IM, Control. Compare with CF treatment, the treatments of SF and IM markedly reduced NH3 volatilization from greenhouse vegetable field by 24.2% and 42.4% (P<0.05), and reduced by 10.1% and 8.3% (P>0.05) under MF and OF treatments, respectively. The NH3 volatilization-induced N losses in the decreasing order of different treatments were MF, OF, CF, SF, IM. Compare with the rest of the applied treatments, the IM treatment consistently showed lower NH3-N loss rate during the whole season. However, the NH3-N loss rates under MF and OF treatments were different during basal fertilization and topdressing periods. In the basal fertilization period, the MF and OF treatments showed lower NH3-N loss rates compare with CF treatment, however, during topdressing period, the NH3-N loss rates under MF and OF treatments were higher than that under CF treatment. 【Conclusion】 Compare with CF treatment, both of the SF and IM treatments could significantly reduce the NH3 volatilization that derived from applied N fertilizer. The IM treatment reduced NH3-N-induced N fertilizer loss in both basal fertilization and topdressing periods, while the SF treatment mainly reduced the NH3 volatilization during basal fertilization period. On balance, both the application of slow-release fertilizer and the technique of integrated management of water and fertilizer were the effective ways in the reduction of NH3 volatilization from greenhouse vegetable field, and were worthy for recommendation.

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    Effects and Mechanism of Humic Acid in Humic Acid Enhanced Phosphate Fertilizer on Fertilizer-Phosphorus Migration
    JING JianYuan,YUAN Liang,ZHANG ShuiQin,LI YanTing,ZHAO BingQiang
    Scientia Agricultura Sinica    2021, 54 (23): 5032-5042.   DOI: 10.3864/j.issn.0578-1752.2021.23.009
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    【Objective】The difference between HA (raw humic acid) and PHA (humic acid which extracted from humic acid enhanced phosphate fertilizers, HAP) on fertilizer-phosphorus migration, Ca2+ and phosphate adsorption characteristics was systematically compared to provide the theoretical basis for the study on high-efficiency mechanism of humic acid enhanced phosphate fertilizer. 【Method】 In this study, HA, HAP, and conventional phosphate fertilizer were prepared in the laboratory, and PHA was extracted by adjusting the pH of HAP’s solution based on the method of alkali-extraction acid-precipitation. The addition of HA or PHA accounted for 0.5% and 5% of the application amount of phosphate fertilizer, and marked with 0.5HA+P, 0.5PHA+P, 5HA+P, and 5PHA+P, respectively. Only phosphate fertilizer application (P) and no fertilizer application (CK) were arranged at the same time. Then, the effects of HA and PHA applicated with phosphate fertilizer on the migration of fertilizer-phosphorus in soil was investigated. In addition, the adsorption characteristics of HA or PHA on Ca2+ and phosphate were studied to reveal the mechanism that HA and PHA showed different performance on phosphorus migration. 【Result】Both HA and PHA could promote the migration of fertilizer-phosphorus. Phosphorus could migrate to 42 mm vertical distance from the fertilizer layer under the treatment of P. However, when phosphate fertilizers application combined with HA and PHA, it could reach 46 mm and 50 mm away from the fertilizer layer, respectively. This result was due to the fact that HA or PHA had a higher adsorption capacity on soil Ca2+, while the application of HA or PHA reduced phosphorus fixation. The cumulative percentage of soil available P in total P application tended to be stable after 42 mm away from the fertilizer layer, and 0.5 HA+P ≈ 5PHA+P>5HA+P>0.5PHA + P>P. The promotion effect of PHA on fertilizer-phosphorus migration would be enhanced with the addition of PHA increase, while HA was the opposite, which might be related to the stronger mobility and the weaker phosphate adsorption of PHA than that of HA. The adsorption of Ca2+ by HA and PHA was the result of membrane diffusion and intra-particle diffusion. However, the difficulty of Ca2+ diffusion to the surface of PHA particles was lower than that of HA, and the difficulty of Ca2+ diffusion in the interior of PHA particles was higher than that of HA. Langmuir isothermal adsorption model could well fit the isothermal adsorption curves of HA or PHA on Ca2+, and the theoretical maximum adsorption capacity of HA on Ca2+ was higher than that of PHA, but the adsorption of PHA on Ca2+ was mainly chemical adsorption.【Conclusion】Both HA and PHA had certain ability to adsorb Ca2+, so they could promote the migration of fertilizer-phosphorus in the soil. However, the migration distance of fertilizer-phosphorus of PHA was longer than that of HA, when phosphate application was combined with HA or PHA. This might be one reason why PHA could improve the use efficiency of phosphate fertilizer.

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    Effects of Straw Returning and Nitrogen Application Rate on Grain Yield and Nitrogen Utilization of Winter Wheat
    WANG XinYuan,ZHAO SiDa,ZHENG XianFeng,WANG ZhaoHui,HE Gang
    Scientia Agricultura Sinica    2021, 54 (23): 5043-5053.   DOI: 10.3864/j.issn.0578-1752.2021.23.010
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    【Objective】A seven-year location-fixed field experiment was carried out to explore the effects of combining straw returning with chemical nitrogen (N) fertilizer on wheat yield, grain protein content, aboveground N uptake, soil nitrate-N (NO3--N) residue at harvest, and apparent N balance in winter wheat-summer maize rotation region of Shaanxi, so as to provide a reference for yield increase and N utilization.【Method】The experiment was arranged in a split block design with two main treatments and five subplots. The main treatments included maize straw returning to soil (straw returning) and removal straw from field (control), and the subplots included five N application rate, i.e., 0 (N0), 84 kg·hm-2 (N84), 168 kg·hm-2 (N168), 252 kg·hm-2 (N252), and 336 kg·hm-2 (N336).【Result】For wheat yield, there was no significant difference between straw returning and control. Compared with N0, applying fertilizer N (including N84, N168, N252, and N336) increased grain yield by 18%-29%. However, compared with N168, there was a risk of yield reduction under high N application rate (N336). Straw returning and N application rate had an interactive effect on wheat yield. Compared with the control, the straw retuning increased grain yield by 5%-6% when N application rates were 252 and 336 kg·hm-2, which was mainly due to the 5%-7% increase in the number of spikes. For grain protein, there was no significant difference between straw returning and control. Compared with N0, applying fertilizer N increased grain protein concentration by 16%-33%. For aboveground N uptake, there was no significant difference between straw returning and control. Compared with N0, applying fertilizer N increased aboveground N uptake by 36%-72%. Straw returning and N application rate had an interactive effect on aboveground N uptake. Compared with the control, the straw retuning increased aboveground N uptake by 5%-8% when N application rates were 252 and 336 kg·hm-2. Compared with control, the straw returning increased the residual soil nitrate nitrogen by an average of 18%, and the increased nitrate nitrogen content was mainly distributed in the 70-170 cm soil layer. For N168 treatment, soil N was in the state of depletion in control, and soil N depletion was effectively compensated when straws were returned to the field. A further increase in N application rate would greatly increase N surplus, resulting in a larger environmental risks. Compared with control, applying fertilizer N had a greater contribution to N surplus.【Conclusion】Straw returning and applying fertilizer N had the ability to increase wheat yield and aboveground N uptake, while also increased residual NO3--N in soil and N surplus. Taking into account wheat yield, soil NO3--N residue, and apparent N balance, the strategy of straw returning combined with 168 kg·hm-2 fertilizer N was beneficial to maintain wheat yield and to protect ecological environment.

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    Effects of Long-Term Reduce/Zero Tillage and Nitrogen Fertilizer Reducing on Maize Yield and Soil Carbon Emission Under Fully Plastic Mulched Ridge-Furrow Planting System
    ZHOU YongJie,XIE JunHong,LI LingLing,WANG LinLin,LUO ZhuZhu,WANG JinBin
    Scientia Agricultura Sinica    2021, 54 (23): 5054-5067.   DOI: 10.3864/j.issn.0578-1752.2021.23.011
    Abstract318)   HTML35)    PDF (1157KB)(258)       Save

    【Objective】 The effects of tillage practices on soil respiration, carbon emission and crop yield under nitrogen reduction were clarified, and the relationship between maize growth and soil carbon emission was revealed.【Method】The long-term tillage practices and reduced fertilization experiment initiated in 2012 within two-year (2018-2019) was conducted at the Rainfed Agricultural Experimental Station of the Gansu Agricultural University in the Gansu province of northwestern China. This experiment is based on the technology of full-film double-ridge and furrow sowing maize with good effect of collecting rainfall and inhibiting evaporation and increasing temperature and soil moisture. The experiment adopted the split plot design, and the main plots were four tillage practices (conventional tillage, rotary tillage, subsoiling, and no-tillage) and the subplot were two nitrogen application levels (nitrogen reduction (200 kg·hm-2) and conventional nitrogen application (300 kg·hm-2)). Based on this experiment, the maize growth, soil respiration rate, carbon emission and soil organic carbon content, carbon emission efficiency (CEE) and net ecosystem productivity (NEP) were assessed.【Result】(1) Tillage practice and nitrogen application level significantly affected the growth of maize, and the effect of tillage practice on dry matter accumulation was mainly in the filling stage and maturity stage. No tillage treatment significantly improved the dry matter accumulation, growth rate and net assimilation rate at these stages, which increased grain yield by 2%-15% compared with other tillage practices; nitrogen application level had a greater effect on dry matter during jointing flowering stage, but the same effect was observed, and there was no significant difference in yield between N1 and N2 under the same tillage practice. (2) The soil respiration rate showed a single-peak curve that first increased and then decreased, reaching its peak in the big bell mouth-flowering period. The effects of tillage practices on soil respiration, carbon emissions and carbon emission efficiency were greater than the nitrogen levels. Compared with rotary tillage, tillage and subsoiling, no tillage decreased soil respiration rate by 4.3%, 12.9% and 24.3%, respectively, and total carbon emission decreased by 21.5%, 13.4% and 31.2%, respectively, while carbon emission efficiency increased by 26.5%-55.9%. Compared with other treatments, no tillage combined with nitrogen reduction reduced total nitrogen and carbon emission by 489-1917.5 kg·hm-2, while the carbon emission efficiency increased by 20.1%-56.2%. (3) All treatments showed a “sink” of atmospheric CO2, but no-tillage and reduced nitrogen fertilizer showed a stronger carbon sink effect. The organic carbon content in 0-5 cm soil layer was significantly increased by 11.3% (P<0.05) compared with conventional tillage; the organic carbon content in 0-10 cm soil layer was increased by 5.8% (P<0.05) compared with conventional tillage. (4) There was a significant positive correlation between the efficiency of carbon emissions and the accumulation of dry matter, the rate of growth and net assimilation rate, and a significant negative correlation between the efficiency of carbon emissions and the organic carbon of the soil. This was mainly because the cultivation practices and application of nitrogen promoted maize’s photosynthetic ability, obtained more CO2, and enhanced maize’s capacity for carbon fixation. 【Conclusion】 Under the condition of 472-491 mm annual precipitation, no tillage combined with nitrogen reduction (200 kg·hm-2) could improve maize yield, improve soil organic carbon content, reduce total carbon emission, and improve carbon emission efficiency. A green yield-increasing technology of full-film double-ridge and furrow sowing maize in the Loess Plateau of Longzhong was recommended to be used in production.

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    Phosphorus Fertilizer Replacement Value of Livestock Manure in Winter Wheat
    XU JiuKai,YUAN Liang,WEN YanChen,ZHANG ShuiQin,LIN ZhiAn,LI YanTing,LI HaiYan,ZHAO BingQiang
    Scientia Agricultura Sinica    2021, 54 (22): 4826-4839.   DOI: 10.3864/j.issn.0578-1752.2021.22.010
    Abstract317)   HTML32)    PDF (504KB)(276)       Save

    【Objective】 Excessive application of phosphorus has not only caused the depletion of phosphate rock resources, but also increased the risk of environmental pollution. Livestock manure has always been used as a good alternative resource for chemical phosphorus. However, due to the complex composition and various influencing factors in the transformation process of phosphorus in animal manure, its effectiveness compared with that in chemical fertilizers has long been controversial. Clarifying the phosphorus replacement value of livestock manure, and the accurate proportion of organic fertilizer phosphorus replacing chemical fertilizer phosphorus, could provide the supporting data for rational application of organic fertilizer phosphorus.【Method】In this study, composted pig manure, chicken manure and cattle manure as well as chemical fertilizer were selected as the research materials. The application rate of P2O5 was set at 6 levels, which were 0, 20, 40, 60, 80 and 100 mg·kg-1 dry soil, respectively. A soil column experiment was conducted to investigate the effects of phosphorus in manure and chemical fertilizer on wheat yield, phosphorus uptake and the content of soil available phosphorus. Furthermore, the relative substitution equivalent of phosphorus in three kinds of manure was statistically analyzed.【Result】 (1) The content of organic and inorganic phosphorus in the three kinds of manure varied much. The proportion of organic phosphorus accounted for 25.9%, 17.6% and 56.5% of total phosphorus in pig, chicken and cattle manures, respectively. The liable phosphorus (H2O-P and NaHCO3-P) was the main phosphorus fraction for the cattle manure, while there was more phosphorus fraction attributed to highly stable phosphorus (HCl-P) in chicken manure and pig manure. (2)There was no significant difference in grain yield between different phosphorus supplies with the same application rate. The phosphorus uptake of wheat with chemical fertilizer was slightly higher than that treated with three kinds of manure. (3) In this study, when the seasonal recovery rate of phosphorus was used as a reference index, the chemical fertilizer equivalent value in chicken, pig and cattle manures to the commercial mineral phosphorus (super phosphate) were 80.3%, 84.3% and 90.4%, respectively. When the relative substitution equivalents of three kinds of manure were calculated by using the regression function between the chemical phosphorus and grain yield, biomass, phosphorus uptake of grain or total phosphorus uptake, the relative substitution equivalents of pig manure were 90.0%, 93.6%, 80.6% and 80.2%, respectively; The relative substitution equivalents of chicken manure were 78.4%, 87.9%, 73.4%, 67.6%, and that of cattle manure were 89.6%, 99.9%, 90.0%, 87.3%. (4) Both the manure and chemical fertilizer could increase the content of available phosphorus in soil, but the manure showed a slight effect than the chemical fertilizer. 【Conclusion】 Based on the integrated methods for calculating substitution equivalent of the present experimental condition, the phosphorus in pig manure could replace 85.7% of equivalent chemical fertilizer P, while chicken manure and cow manure could replace 77.6% and 91.4%, respectively.

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    Theoretical Connotations and Pricing Mechanisms for Agricultural Ecological Compensation Within the Context of Green Development
    ZHOU Ying,MEI XuRong,YANG Peng,LIU Jing
    Scientia Agricultura Sinica    2021, 54 (20): 4358-4369.   DOI: 10.3864/j.issn.0578-1752.2021.20.010
    Abstract621)   HTML37)    PDF (541KB)(435)       Save

    【Objective】Within the context of green development, the research on mechanisms for agricultural ecological compensation has become an extremely urgent and strategic task for the protection of the ecological environment in functional agricultural areas in China. The standards for ecological compensation directly affect the actual effect of policy internalization and externality. The redefine the theoretical connotations of agricultural ecological compensation, determine the concepts and basis of compensation pricing, and are the effective way to improve the accuracy and directivity of subsidy policy. 【Method】Using normative analysis as well as inductive and deductive methods, the boundary of green development oriented agricultural ecological compensation policy was re-positioned, and the types and content of agricultural ecological compensation were systematically divided, in an attempt to develop a pricing mechanism that focused on the measurement of external effects and scientifically answer the core questions of "why compensate?" and "what to compensate?" in the field of agricultural ecological compensation. 【Result】Firstly, the connotations of ecological compensation for agricultural green development were scientifically analyzed: ecological compensation for agricultural green development is an environmentally friendly and economic means of producing spillover benefits (costs) internalization when protecting agricultural resources and the environment. The core content of compensation includes two parts: the protection compensation for agricultural resource assets, and the compensation for green agricultural production behavior. Secondly, According to the environmental impact of technology on the ecosystem, the compensation content can be divided into four types: (1) the compensation for resource development and construction, aiming at the reduction of positive externality in the environment and the loss of private interests; (2) the compensation for resource protection and utilization, aiming at a reasonable return for the preservation and proliferation of ecological capital; (3) the compensation for environmental pollution and protection, aiming at reducing the costs and losses from negative externality in the environment; (4) the compensation for environmental quality improvement, aiming to compensate for investment and income losses from improving the positive externality of the environment. Thirdly, the accounting basis of compensation standards for these four types of compensation was developed, among these standards: the compensation for resource development and construction should be based on the replacement cost of resource production or maintenance, the expected return of resource assets, and the opportunity cost of development; the compensation for resource protection and utilization should be based on the direct investment of resource protectors, the opportunity cost of development, and the ecological service value of resource protection; environmental pollution control and quality improvement belong to compensation for the application of green technology, and its compensation pricing is mainly based on the additional production costs, environmental costs, development opportunity cost, and technology spillover benefit value. 【Conclusion】The innovation of an agricultural ecological compensation system guided by green development in China includes: first, which should, on the one hand, divide the policy boundary of agricultural ecological compensation from the perspective of the environmental contribution of green production, and on the other hand, should compensate for the cost investment and personal interest loss of reducing negative environmental externalities and improving positive environmental externalities; second, from the perspective of an externality double boundary, the ideas and principles of compensation pricing shall be put forward: the compensation standard should be determined from the vertical boundary of theoretical research and the horizontal boundary of practical application, combined with the government's ability to make financial payment.

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    Fertilizer Reduction Potential and Economic Benefits of Crop Production for Smallholder Farmers in Shaanxi Province
    MI XiaoTian,SHI Lei,HE Gang,WANG ZhaoHui
    Scientia Agricultura Sinica    2021, 54 (20): 4370-4384.   DOI: 10.3864/j.issn.0578-1752.2021.20.011
    Abstract291)   HTML30)    PDF (542KB)(268)       Save

    【Objective】The material input of agriculture production is generally high for smallholder farmers, and the application rate of chemical fertilizers will change with the evolution of crop structure. Understanding the situation of nutrient input and economic benefits of smallholder to cereal crop, oil crop and cash crop could help guide scientific fertilization and improve economic benefits. 【Method】In 2018, a questionnaire survey was conducted on the production of major crops in Shaanxi Province. The cereal crop (wheat, maize, rice, millet, and potato), oil crop (canola and soybean), and cash crop (apple, tomato, and flue-cured tobacco) were considered as targeted crops, and a total of 1 709 questionnaires were obtained. Further, the fertilization status of smallholder, the potential of fertilizer reduction, and economic benefits according to yield level of different crops were evaluated. 【Result】For the production of wheat, maize, rice, millet, and potato, the mean yield was 4.6, 7.3, 8.3, 3.7, and 19.8 t·hm-2, respectively; the mean nitrogen (N) fertilizer rate was 177, 247, 186, 255, and 209 kg N·hm-2, respectively; the mean phosphate (P) fertilizer rate was 102, 103, 88, 142, and 125 kg P2O5·hm-2; mean potassium (K) fertilizer rate was 37, 47, 64, 53, and 110 kg K2O·hm-2, respectively. For canola and soybean production, the mean yield was 2.4 and 2.7 t·hm-2, N fertilizer rate was 156 and 99 kg N·hm-2, P fertilizer rate was 80 and 63 kg P2O5·hm-2, K fertilizer rate was 56 and 26 kg K2O·hm-2, respectively. For the production of apple, tomato, and tobacco, the mean yield was 23.8, 93.5, and 2.7 t·hm-2, respectively; N fertilizer rate was 731, 471, and 118 kg N·hm-2, P fertilizer rate was 482, 387, and 118 kg P2O5·hm-2, K fertilizer rate was 535, 447, and 132 kg K2O·hm-2, respectively. N and P fertilizers were usually over-applied, while both over-application and under-application of K fertilizer coexisted. The potential of N, P, K fertilizer reduction ranges from 28% to 60%, 52% to 66%, and 11% to 51% for cereal crop, 33%, 37% and 46% for canola, respectively. However, the application rate of P and K fertilizer needed to increase by 11% and 28% for soybean production, respectively. The potential of N, P, and K fertilizer reduction ranged from 41% to 67%, 65% to 70%, and 49% to 64% for apple and tomato production, respectively. For tobacco production, the application rate of P fertilizer could decrease by 53%, while the application rate of N fertilizer needed to increase by 22% and 11% for farmers with medium and high-yielding, respectively. The source of N was mainly compound fertilizers and urea, and the sources of P and K were mainly compound fertilizers. For the way of chemical fertilizer application, most of N fertilizer was applied as basal fertilizer, and a small part was supplemented by topdressing, while almost all P and K fertilizers were applied as basal fertilizer. For cereal crop, oil crop, and cash crop, the cost of fertilizer application accounted for 31%-52%, 57%-59% and 48%-65% of total input, respectively, and the net economic benefit ranged from 0.44×104to 1.63×104, 0.75×104to 0.84×104, and 4.19×104 to 15.05×104yuan/hm2, respectively. Because the net economic benefit of high-yielding in cash crop, e.g., apple and tomato, was higher than that of cereal crop and oil crop, smallholder farmers were more inclined to grow them. However, the substantial application of chemical fertilizer in cash crop production brought great environmental risks. 【Conclusion】The main target of fertilizer reduction and benefit improvement was smallholder with low and middle-yielding level. Compared with cereal crop and oil crop, the economic benefit of cash crop, especially for apple and tomato, was higher, while their potential of fertilizer reduction was also higher due to substantial application of chemical fertilizer. Notably, the result of the study also demonstrated that there was also insufficient application of fertilizer in crop production, e.g., soybean and tobacco. In conclusion, the fertilizer management of smallholder varied greatly. Improving the level of fertilizer management for smallholder was conducive to increasing both yield and economic benefits, and thus contributing to sustainable crop production.

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    Effects of Deep Plowing and Organic-Inorganic Fertilization on Soil Water and Nitrogen Leaching in Rice Field
    WANG JinYu,CHENG WenLong,HUAI ShengChang,WU HongLiang,XING TingTing,YU WeiJia,WU Ji,LI Min,LU ChangAi
    Scientia Agricultura Sinica    2021, 54 (20): 4385-4395.   DOI: 10.3864/j.issn.0578-1752.2021.20.012
    Abstract340)   HTML40)    PDF (642KB)(347)       Save

    【Objective】Aimed at the problems of shallow soil plow layer, thickening of plow pan and soil hardening caused by perennial shallow ploughing and unreasonable fertilization in rice-wheat rotation area in the middle and lower reaches of Yangtze River in China,the effects of deep plowing (breaking part of plow pan) and fertilization on paddy field soil bulk density, soil compaction, soil water leaching and nitrogen leaching were studied to illuminate the response of nitrogen leaching to two tillage methods and three fertilization measures, and then provide theoretical basis for the construction of plow layer in the paddy soil. 【Method】 (1) Two tillage methods (rotary tillage 12 cm and deep plowing 20 cm) and three equal nitrogen fertilization treatments (single inorganic fertilizer treatment T1, returning straw with inorganic fertilizer treatment T2, organic manure with inorganic fertilizer treatment T3) were established in Shucheng County, Anhui Province in 2015. Soil water leaching and nitrogen leaching in rice season as well as soil bulk density and soil compaction were monitored dynamically in 2019-2020; (2) The soil-column experiment from paddy field was conducted to monitor. Water leaching from the treatment of deep plowing 30 cm in depth (total breaking of soil plow pan) was studied. 【Result】 (1) Field experiment results showed that the soil bulk density and soil compaction from the treatment of deep plowing 20 cm in depth were declined in rice season compared to those from the treatment of rotary tillage 12 cm in depth. Compared with the treatment of rotary tillage 12 cm in depth, the soil water leaching from the treatment of deep plowing 20 cm in depth increased by 7.4% in tillering stage, and there was no obvious change in soil water leaching after rice booting stage. From the whole rice growth period, the difference of soil water leaching between the treatment of deep plowing 20 cm in depth and the treatment of rotary tillage 12 cm in depth was not significant; (2) The results of soil-column experiment showed the soil water leaching from the treatment of deep plowing 30 cm in depth (total breaking of soil plow pan) increased significantly by 19.0% and 11.0% in flooding and 23.0% and 21.5% in non-flooding, respectively, compared with the treatment of rotary tillage 12 cm in depth and the treatment of deep plowing 20 cm in depth; (3) Nitrate nitrogen was dominant form of nitrogen in the soil water leaching. The concentration of nitrate nitrogen in soil water leaching from T3 treatment decreased significantly compared with that of T1 and T2 treatment after rice booting stage, but the difference of ammonium nitrogen concentration in soil water leaching from T1, T2 and T3 treatment were not significant; (4) From the whole growth period of rice, the difference of nitrogen leaching from the treatment of rotary tillage 12 cm in depth and the treatment of deep plowing 20 cm in depth was not significant, while the three treatments of fertilization had obvious difference on nitrogen leaching. Under the condition of deep plowing 20 cm in depth, the nitrogen leaching rates of T1, T2 and T3 treatment were 10.7, 11.7 and 9.1 kg N·hm-2 respectively, and under the condition of rotary tillage 12 cm in depth, the nitrogen leaching rates of T1, T2 and T3 treatment were 9.83,11.21 and 8.58 kg N·hm-2, respectively. T3 treatment decreased significantly nitrogen leaching compared to T1 and T2 treatment. 【Conclusion】 Deep plowing 20 cm in depth can improve soil physical structure, however, soil water leaching and nitrogen leaching are not significantly increased, and the combination of organic manure and inorganic fertilizer can significantly reduce nitrate nitrogen leaching. These results are of theoretical significance for the building of deep and fertile tillage layer in the clay paddy soil with high plow pan (such as red-yellow soil) in the middle and lower reaches of the Yangtze River through deep plowing measures, combined application of organic manure and inorganic fertilizer.

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    Response of Wheat Yield and Protein Concentration to Soil Nitrate in Northern Wheat Production Region of China
    MA Yue,TIAN Yi,YUAN AiJing,WANG HaoLin,LI YongHua,HUANG TingMiao,HUANG Ning,LI Chao,DANG HaiYan,QIU WeiHong,HE Gang,WANG ZhaoHui,SHI Mei
    Scientia Agricultura Sinica    2021, 54 (18): 3903-3918.   DOI: 10.3864/j.issn.0578-1752.2021.18.010
    Abstract354)   HTML32)    PDF (735KB)(352)       Save

    【Objective】The changes of wheat grain yield and protein concentration caused by reduced nitrogen (N) fertilizer at different soil nitrate N residue levels were clarified, for the purpose of N fertilizer reduction and soil residual nitrate N decline in northern wheat production region of China.【Method】In our research, 43-site field experiments from 2018 to 2019 were conducted in northern wheat region of China, to investigate the effects of reduced N fertilizer on grain yield, protein concentration, yield components, and N uptake and utilization of wheat at different soil nitrate N residue levels. 【Result】The results showed that the recommended fertilizer application based on soil nitrate test (RF) could reduce N rates by 55 kg·hm-2, correspond 26% of farmers’ fertilizer application (FF). Compared with the FF, the grain yield (5 885 kg·hm-2) of RF was increased by 3.1%, while no significant difference was observed for grain protein concentration between the two treatments. For the minimum of grain yield was found to be 4 252 kg·hm-2 when the soil nitrate N residue was less than 55 kg·hm-2, and the maximum was 7 186 kg·hm-2 at the soil nitrate N residue level of 55-100 kg·hm-2. Higher soil nitrate N residue was not capable to increase the grain yield sustainability. For recommended fertilizer application based on soil nitrate test without N added (RF-N), the grain yield was significantly decreased with the corresponding soil nitrate N residue less than 100 kg·hm-2, while no obvious reduction for grain yield for the RF regardless of nitrate N residue levels in soils. The grain protein concentration reached the highest when the soil nitrate-N residue was higher than 300 kg·hm-2. The grain protein concentration was significantly decreased in RF-N, when the soil nitrate N residue was less than 200 kg·hm-2, but it was not influenced obviously by soil nitrate N residue in the RF treatment. With soil nitrate N residue ranging from 55 to 100 kg·hm-2, the grain protein concentration of FF and RF was 124.5 and 123.1 g·kg-1, respectively. For RF, the N fertilizer uptake efficiency and N partial factor productivity were 1.36 and 45.7 kg·kg-1, respectively; which were significantly increased by 61.5% and 57.1%, respectively, compared with the FF. 【Conclusion】For maintaining the higher grain yield and protein concentration of wheat, the residual nitrate N in 0-100 cm soil at harvest should be kept at 55-100 kg·hm-2 in northern wheat production region. Determination of reasonable N fertilizer rates, based on combination of target grain yield, grain protein concentration and soil nitrate testing, played important roles in achieving N fertilizer reduction and agricultural green production in wheat fields.

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    Source Analysis and Control Strategies of Non-Point Source Pollution in Typical Agricultural Small Watershed: A Case Study of Danjiangkou Water Conservation Area
    GONG ShiFei,DING WuHan,JU XueHai,XIAO NengWu,YE QingSong,HUANG Jin,LI Hu
    Scientia Agricultura Sinica    2021, 54 (18): 3919-3931.   DOI: 10.3864/j.issn.0578-1752.2021.18.011
    Abstract374)   HTML34)    PDF (527KB)(215)       Save

    【Objective】The investigation and analysis of agricultural non-point source pollution status in typical small watershed of Danjiangkou Reservoir Area were conducted to parse the pollution load and pollution sources of non-point agricultural sources in this area, so as to provide the reference for formulating targeted prevention and promoting the green development of agriculture. 【Method】Field visits were carried out through questionnaire survey in the Tanjiawan watershed, and the pollution sources, such as planting, breeding and living, were classified in two villages. Meanwhile, the pollution load was estimated according to the export coefficient method approach and the equivalent standard pollution load method. 【Result】The results showed that: the actual load of agricultural non-point source pollution in Tanjiaban watershed decreased from 162.32 t in 2015 to 27.79 t in 2020, the total equivalent standard pollution load decreased from 62.44 m3 to 21.14 m3, and the dominant source of pollution changed from land utilization to livestock and poultry breeding. The total annual loads of TN, TP and COD of agricultural non-point source pollution in the watershed were 5.56, 0.86 and 21.37 t, respectively. The contribution of different pollution sources were found in the following order: livestock and poultry breeding > land utilization > rural life. TN, TP and COD load of pig breeding accounted for 50.91%, 64.20% and 46.66% of the total load of the watershed, respectively, making it the most important source of pollution in the region. TN was the most important non-point agricultural source in the watershed, and its equivalent standard pollution load accounted for 52.6% of the total load, followed by TP, with a pollution load rate of 40.7%, and the minimum equivalent standard pollution load rate of COD was 6.7%. According to the result of environmental pollution risk assessment, the alarm value of livestock and poultry manure load in Tanjiawan watershed was 0.489 and the risk level wasⅡ, indicating the environmental pollution was "slightly". There was still room for expansion of 10 815 pig’s equivalent on the basis of the current total amount of cultivation in the watershed. Since 2015, the intensity of non-point agricultural source pollution in Tanjiawan watershed has been reduced significantly. 【Conclusion】It was of great significance to keep a reasonable amount of livestock and poultry breeding, and to take some effective measures to promote the sustainable emission reduction of non-point agricultural source pollution in the typical watershed of the Danjiangkou Reservoir area.

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    Effects of Phosphorus Application Levels on Growth and Yield of Winter Wheat Under Different Crops for Rotation
    XUE HuaLong,LOU MengYu,LI Xue,WANG Fei,GUO BinBin,GUO DaYong,LI HaiGang,JIAO NianYuan
    Scientia Agricultura Sinica    2021, 54 (17): 3712-3725.   DOI: 10.3864/j.issn.0578-1752.2021.17.013
    Abstract398)   HTML56)    PDF (527KB)(412)       Save

    【Objective】 In order to explore the reasonable system of crops for rotation with wheat and its phosphorus (P) fertilizer management technology, the effects of P application levels on growth and yield of wheat under different crops for rotation were studied. 【Method】 From 2018 to 2019 and 2019 to 2020, the winter wheat was planted under different crops for rotation of peanut (PCR), maize (MCR) and peanut intercropping maize (ICR), with different P application levels, including P0 (0 kg P2O5·hm-2), P90 (90 kg P2O5·hm-2), P180 (180 kg P2O5·hm-2) and P270 (270 kg P2O5·hm-2). Effects of P levels on tiller and effective spike rate, grain filling rate, dry matter accumulation and distribution ratio, and yield components of winter wheat were investigated. 【Result】 (1) Under the same crops for rotation, the maximum number of tillers per unit area, the number of effective tillers, dry matter accumulation and dry weight per spike of winter wheat were P270>P180>P90>P0 treatment with the increase of P application rate. But the grain number per spike, the distribution rate of dry matter to grain and yield of winter wheat increased at first and then decreased, and reached the maximum under P level of P180. (2) Under different crops for rotation, the maximum number of tillers and effective tillers per unit area of winter wheat were PCR>ICR>MCR under different P levels. The dry matter weight and yield of winter wheat under PCR were higher than those under ICR and MCR with P0 and P90 levels, but ICR under P180 and P270 levels, the dry matter quality and yield of winter wheat were higher than those under PCR and MCR. (3) According to the fitting curve of P application and yield, the highest yield of winter wheat was 10 493.6 kg·hm-2, and the optimal economic yield of P level was 177.0 kg·hm-2 under PCR. The highest yield of winter wheat was 10 749.8 kg·hm-2, while the optimal economic yield of P level was 178.9 kg·hm-2under ICR. The highest yield of winter wheat was 9 936.2 kg·hm-2, and the optimal economic yield of P level was 189.3 kg·hm-2under MCR. 【Conclusion】 The number of effective tillers, dry matter accumulation and transferring, grain filling and yield formation of winter wheat under crops for rotation of peanut or crops for rotation of maize intercropping peanut were better than those of under crops for rotation of maize. Compared with crops for rotation of maize, the yield potential of winter wheat in crops for rotation of peanut or maize intercropping peanut was higher, and the application amount of phosphorus in the optimal economic yield was lower, which was 177.0-178.9 kg·hm-2.

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    Effects of Nitrogen Application Rate on Nitrogen Use Efficiency, Yield and Quality of Late Sowing Rapeseed
    LI XiaoYong,GU ChiMing,LIU Kang,LIAO Xing,HUANG Wei,YANG ZhiYuan,QIN Lu
    Scientia Agricultura Sinica    2021, 54 (17): 3726-3736.   DOI: 10.3864/j.issn.0578-1752.2021.17.014
    Abstract356)   HTML37)    PDF (480KB)(326)       Save

    【Objective】 Under the multi-cropping system in the Yangtze River Basin, the rapeseed sowing date was delayed, resulting in low yield and poor quality. In this study, in order to explore the effect of different nitrogen rates on the yield and seed quality of late sowing rapeseed, the related indexes of late sowing rapeseed, including yield and its components, agronomic characters, nutrient accumulation, grain quality, and so on, were measured under different nitrogen application levels in order to find out the best nitrogen rate of late sowing rapeseed. 【Method】 Field experiments were carried out in Yingcheng and Huanggang, Hubei province. A rapeseed variety“Zhongyouza19”was used as the material, and two sowing dates (S1,10th October; S2, 10th November) and 4 nitrogen rates (N0, 0; N1, 120 kg·hm-2; N2, 240 kg·hm-2; N3, 360 kg·hm-2) were set in this study. 【Result】 (1) Late sowing of rapeseed significantly reduced the yield. With an increase in nitrogen rate, the pods per plant, seeds per pod and 1000-seed weight had a significant increase under different sowing dates. Compared with N0, the yield under N1, N2 and N3 was increased by 31.9%, 68.6% and 79.8% on average under normal sowing date, respectively, and increased by 36.0%, 82.0% and 87.3% on average under late sowing date, respectively. (2) With the sowing date delaying, the root crown diameter, plant height and branch height were decreased significantly, and the above-ground biomass were increased, whereas the root biomass and the root-shoot ratio were decreased. With an increase in nitrogen rate, the root crown diameter, plant height, branch height, the root and shoot biomass were increased, but the root-shoot ratio was decreased, in addition, the lodging angle were increased by 162.7%, 254.7% and 374.7% on average under normal sowing date, respectively, and increased by 105.5%, 208.7% and 303.1% on average under late sowing date, respectively. Lodging was more severe under higher nitrogen rate. (3) With the sowing date delaying, the nitrogen content and nitrogen uptake in the root were decreased. The nitrogen content in the seed was increased, but the nitrogen uptake and oil content in the seed were decreased. Then, the nitrogen content in the stem and the pod shell did not change significantly, but the nitrogen uptake increased significantly. With an increase in nitrogen rate, the nitrogen content and uptake in each part were increased and the oil yield also showed an increasing trend, but the oil yield (1 830.5 kg·hm-2 and 1 534.5 kg·hm-2 (Yingcheng), 1 535.1 kg·hm-2 and 1 220.0 kg·hm-2(Huanggang)) and the seed nitrogen use efficiency (34.88% and 31.14% (Yingcheng), 27.95% and 25.48% (Huanggang)) reached the maximum at the nitrogen rate level of 240 kg·hm-2under different sowing dates. There was a significant positive correlation between seed nitrogen use efficiency and grain yield and oil yield, but there was no correlation with lodging angle. The grain yield and oil yield could be improved by increasing seed nitrogen use efficiency without aggravating lodging. 【Conclusion】 Increasing nitrogen rate could improve the yield of late sowing rapeseed, but the nitrogen rate should be controlled at about 240 kg·hm-2 to further control lodging and obtain maximum oil yield.

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    Identification of Functional Substances from Rice Straw Obtained by Pyrolysis and Enzymolysis and Its Effect
    TANG SiYu,LIU QiuMei,MENG XiaoHui,MA Lei,LIU DongYang,HUANG QiWei,SHEN QiRong
    Scientia Agricultura Sinica    2021, 54 (15): 3250-3263.   DOI: 10.3864/j.issn.0578-1752.2021.15.010
    Abstract330)   HTML34)    PDF (4150KB)(389)       Save

    【Objective】 To explore the effect of agricultural wastes (rice straw) on plant growth, the identification and analyzation of the small molecules that may exist in the high-temperature extracts and enzymolysis solution of rice straw were performed, and the promoting effect of these substances on cucumber growth was also evaluated.【Method】 The high-temperature extract solution of rice straw was prepared by high temperature water extraction at 115℃ for 30 min. The condensation of the extracellular proteins from Trichoderma guizhouense NJAU 4742 under the induction of rice straw was obtained by ammonium sulfate precipitation method, which was used to hydrolyze the rice straw to prepare rice straw enzymatic hydrolysate. The high-temperature extract and enzymolysis solution of rice straw were diluted into different times, and the growth-promoting effects were verified by cucumber hydroponic experiment. The high-temperature extract and enzymatic hydrolysis of rice straw were identified and compared by UHPLC-QE-MS non-target metabolomics detection technology. Under the control of the acquisition software (Xcalibur 4.0.27, Thermo), the QE mass spectrometer collects primary and secondary mass spectrometry data in the information-related acquisition mode for the high-temperature extract and enzymatic hydrolysate of rice straw. Through the self-written R program package (the kernel was XCMS), the original data was processed for peak identification, peak extraction, peak alignment and integration, and then it was matched with the BiotreeDB (V2.1) self-built MS database for substance annotation. Finally, the growth-promoting effects of some identified substances were verified by the cucumber hydroponic experiment.【Result】 The results showed that both high-temperature extract and enzymatic hydrolysate liquid of rice straw could promote the growth of cucumber seedlings at appropriate concentrations, and the enzymatic hydrolysate of rice straw showed significant growth promoting effect on cucumber when diluted for 100 times. Compared with the CK, the dry weight of overground part, underground part and plant height of cucumber plants treated with 100 times dilution increased by 52.64%, 55.05% and 21.43%, respectively, and the number of plant root tips increased by 31.95%. The high-temperature extract of rice straw owned the best growth promotion effect when it was diluted 50 times, in which the dry weight of overground part, the underground part and the plant height of cucumber plants increased by 44.16%, 63.38% and 55.56%, respectively, and the number of plant root tips increased by 64.44%, compared with CK. The UHPLC-QE-MS non-target detection technology results showed that 714 different substances were identified in the high-temperature extract of rice straw and 638 different substances were identified in the enzymatic hydrolysis solution, among which acetylcholine, L-carnitine and myo-inositol were screened out. Meanwhile, the standard products of these three substances were added to the cucumber root system, and the results showed that they all had considerable promotion effect on cucumber growth. Acetylcholine at the concentration of 1 μmol·L-1, 10 μmol·L-1 and 100 μmol·L-1 could all promote the growth of cucumber. Compared with CK, the exogenous acetylcholine at 1 μmol·L-1 concentration increases the dry weight of cucumber shoots by 54.69% and the dry weight of roots by 73.67%, the number of root tips increased by 130.5%; Exogenous L-carnitine was beneficial to the growth of cucumber plants at the concentration of 0.1 mmol·L-1 and 1 mmol·L-1. Compared with CK, the dry weight of cucumber shoots increased by 33.79% and 30.19%, and the dry weight of roots increased by 44.97% and 48.82%, the number of cucumber root tips increased by 41.8% and 49.9%, respectively; Exogenous myo-inositol at the concentration of 0.05 mmol·L-1 and 0.1 mmol·L-1 could promote the growth of cucumber. Compared with CK, the dry weight of cucumber shoots increased by 36.66% and 30.15%, roots dry weight increased by 69.82% and 51.78%, and the number of cucumber root tips increased by 149.0% and 96.7%, respectively.【Conclusion】 In brief, both the high-temperature extract and the enzymatic hydrolysate of rice straw could significantly promote the growth of cucumber, and the acetylcholine, L-carnitine and myo-inositol were detected by LCMS in the pyrolysis and enzymatic hydrolysate of rice straw, which were considered as the functional substances in rice straw.

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    Effects of Drip Irrigation Methods on Photosynthetic Characteristics, Yield and Irrigation Water Use of Apple
    LIU Xing,CAO HongXia,LIAO Yang,ZHOU ChenGuang,LI HuangTao
    Scientia Agricultura Sinica    2021, 54 (15): 3264-3278.   DOI: 10.3864/j.issn.0578-1752.2021.15.011
    Abstract495)   HTML44)    PDF (1957KB)(451)       Save

    【Objective】 The aim of this study was to explore a high-efficient production drip irrigation model of apple tree in Loess Plateau.【Method】 In this study, 8-year-old Hanfu apple trees were took as the research object with different irrigation amount and pattern experiments. These experiments were divided into three treatment groups of root-divided alternative irrigation(ADI), single pipe drip irrigation(UDI) and double pipe drip irrigation(BDI). ADI, UDI and BDI were supplied with three different irrigation levels: high water (W1), middle water (W2) and low water (W3), respectively. Therefore, there were nine treatments based on orthogonal experiment design in number. Then, the responses of the important apple tree parameters, including canopy structure, photosynthetic characteristics, yield and irrigation efficiency, were studied.【Result】 The results showed that less irrigation amount (W2 and W3) significantly reduced leaf area index, leaf inclination angle and clumping index (P<0.05), and increase the irrigation water use efficiency. Compared with single pipe drip irrigation, the drip pattern of alternate root division significantly increased leaf area index (P<0.05), and significantly decreased leaf inclination angle and clumping index (P<0.05). The net photosynthetic rate, transpiration rate, stomatal conductance and carboxylation efficiency of apple leaves at 11:00 increased at first and then decreased with the increase of DAF. At the fruit expansion stage (DAF=80 d), the net photosynthetic rate, carboxylation efficiency and leaf instantaneous water use efficiency under ADI-W2 were higher than that under other patterns. The diurnal variation curve of net photosynthetic rate of apple leaves under different water treatments showed “M” pattern. The phenomenon of “midday depression” of net photosynthetic rate under ADI treatment was not obvious. The peak value of instantaneous water use efficiency of leaves of all treatments appeared at 10:00 a.m, besides the treatment of ADI-W2. ADI-W2 delayed the emergence of peak value, and exhibited a highest daily average instantaneous water use efficiency (3.22 μmol·mmol-1). Furthermore, ADI-W2 had the best hardness (9.09 kg·cm-2), fruit shape index (0.88), big fruit rate (63.46%), single fruit weight (224.12 g) and yield (33 010.15 kg·hm-2). The combination with W3 could improve the irrigation water use efficiency, and the irrigation water use efficiency under ADI-W3 treatment (36.21 kg·m-3) was the highest.【Conclusion】 Finally, ADI-W2 treatment could be defined to be the best drip irrigation mode of water-saving and yield increasing of apple comprehensive scoring method in Loess Plateau area in this study. The results provided a scientific theoretical support for apple drip irrigation management in Loess Plateau.

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    Advance in Indicator Screening and Methodologies of Soil Quality Evaluation
    LI Xin,ZHANG WenJu,WU Lei,REN Yi,ZHANG JunDa,XU MingGang
    Scientia Agricultura Sinica    2021, 54 (14): 3043-3056.   DOI: 10.3864/j.issn.0578-1752.2021.14.010
    Abstract2108)   HTML112)    PDF (949KB)(1124)       Save

    【Objective】 The objectives of the present study were to synthesize the current information on soil quality assessment method and indicator system, and to present the hot topics and frontiers related to soil quality, so as to, provide references for Chinese scholars and experts in the field of soil quality evaluation research and application. 【Method】 The published articles regarding the selection of soil quality indicators, construction of minimum data set, and selection of soil quality evaluation methods were collected based on Web of Science and CNKI databases using bibliometrics method, and a total of 415 articles and 155 minimum data sets related to soil quality evaluation were screened. Development trend, frontier fields and current problems of global soil quality assessment during the past 30 years were analyzed according to selection frequency of indicators, assessment method and construction of minimum data set. 【Result】 The soil quality evaluation indicator system mainly included 25 physical, 36 chemical, 35 biological and 19 environmental indicators. Soil organic matter, as the core indicator of soil quality, was selected with the highest frequency of 96.6%, followed by pH, total nitrogen, available phosphorus, available potassium, and bulk density, with a frequency more than 50%. The selection frequency of biological indicators such as microbial biomass and soil enzyme activity was less than 25%, while increasing over time. Principal component analysis, minimizing indicator redundancy and reflecting most of the information of original variables, was the most widely used for minimum data set construction method. Soil organic matter, available phosphorus, bulk density, and pH were selected into the minimum data set with a frequency of 67.7%, 43.2%, 34.8%, and 34.2%, respectively, being widely used to characterize soil quality. Nowadays, the most studies on soil quality evaluation focus on the utilization of principal component analysis to select soil quality indicators and establish soil quality index for comprehensive soil quality evaluation, which was suitable for sustainable soil management.【Conclusion】 Soil organic matter, available phosphorus, soil pH, bulk density and soil water content were the main parameters selected for soil quality evaluation. Construction a comprehensive and objective soil quality indicator system and the integration with the information technology would be the focus in future research. The application of evaluation indicators in large-scale soil quality assessment was the trend of future development.

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    Contribution of Carbon Sources in Sedimentary Soils Combining Carbon and Nitrogen Isotope with Stable Isotope Model
    LI Na,SUN ZhanXiang,ZHANG YanQing,LIU EnKe,LI FengMing,LI ChunQian,LI Fei
    Scientia Agricultura Sinica    2021, 54 (14): 3057-3064.   DOI: 10.3864/j.issn.0578-1752.2021.14.011
    Abstract509)   HTML35)    PDF (818KB)(706)       Save

    【Objective】To study the sources of deposited soil organic carbon (SOC) under different land use patterns in a typical small watershed in the brown soil hilly area of western Liaoning through eroded sedimentation, and to provide a scientific reference for the reasonable control of soil carbon loss caused by soil erosion in the small watershed. 【Method】Through field sampling of small watersheds in the hilly and gully area of western Liaoning, the sources of deposited soil carbon in the small watersheds were studied and their contribution was quantified. Using GIS and GPS technology to analyze the surface soil of 4 different land use types (cropland, forest, grassland, gully) in the small watershed and 3 locations of the check dam in the small watershed (S1 in front of the dam, S2 in the middle of the dam, S3 behind the dam) 0-100 cm soil profile was sampled to analyze the carbon source of the sedimentary soil based on a mixed carbon and nitrogen isotope model.【Result】Using13C and15N isotopic characteristics and their elemental composition qualitative and quantitative identification of soil organic carbon in eroded sediments in the hilly and gully area of western Liaoning was carried out. The SOC loss was primarily from cropland, accounting for 58.75%, followed by gully (25.49%), forest (9.2%), and grassland (6.49%). 【Conclusion】 The stable isotope SIAR mixing model, as a reliable "fingerprint" tool, could be successfully employed to estimate the contribution of various C sources within a complex ecosystem, The research results can provide theoretical references for soil protection and nutrient loss control in small watersheds affected by water erosion, and for maintaining the sustainability of the ecosystem.

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    Response of Water Use and Yield of Dryland Winter Wheat to Nitrogen Application Under Different Rainfall Patterns
    LIU PengZhao,ZHOU Dong,GUO XingYu,YU Qi,ZHANG YuanHong,LI HaoYu,ZHANG Qi,WANG XuMin,WANG XiaoLi,WANG Rui,LI Jun
    Scientia Agricultura Sinica    2021, 54 (14): 3065-3076.   DOI: 10.3864/j.issn.0578-1752.2021.14.012
    Abstract291)   HTML28)    PDF (698KB)(234)       Save

    【Objective】Rainfall and nitrogen application are the main factors affecting winter wheat production in Weibei dryland, especially the interannual variability of rainfall is large. Therefore, their yield-increasing effects are significantly affected by the type of rainfall year. In this study, the effects of nitrogen rates on water use, grain yield and protein content in dryland wheat field under different rainfall patterns were analyzed, which provided a theoretical basis for “nitrogen applying according to rain” and ensuring stable yield and high quality of winter wheat in Weibei Dryland.【Method】A 3-year field experiment (2017-2020) of winter wheat (Jinmai 47) was performed with different nitrogen fertilization at five levels (0, 60, 120, 180 and 240 kg·hm-2, represented as N0, N60, N120, N180, and N240, respectively) in Heyang County, located in Weibei dryland of Shaanxi, and the effects of nitrogen application under different rainfall patterns on soil water dynamics, water use efficiency (WUE), wheat yield performance and grain protein content were evaluated. 【Result】Different rainfall patterns had significant impacts on soil water storage before sowing (SWSS), soil water content during growth period, ET, WUE, yield and protein content of winter wheat. (1) There was a linear correlation between rainfall in fallow period (from July to September) and SWSS, with an increment of 0.9 mm SWSS per 1 mm rainfall. In the humid and normal years with adequate rainfall during fallow stage, the SWSs in present winter wheat growth season was not significantly influenced by the increase of nitrogen fertilization in previous growth season. However, in the dry year with less rainfall in fallow stage, the SWSS in present winter wheat growth season decreased significantly by 15.4 mm when nitrogen fertilization in previous growth season was increased by each 100 kg·hm-2. Compared with dry and normal year, the soil water content of 0-200 cm soil layer during growth period of winter wheat could be increased in humid rainfall year, thus evapotranspiration (ET) was increased by 35.7% and 6.6%, respectively. The soil water accumulation of 0-120 cm soil depth during the growth period fluctuated greatly under the influence of rainfall and the growth of winter wheat. However, the soil water content in 160-200 cm deep soil depth showed a stable change trend. Compared with dry and normal year, the WUE in humid pattern was increased by 55.7% and 26.5%, the grain yield was increased by 112.3% and 39.1%, and protein content (PC) was decreased by 8.3% and 5.2%, respectively. (2) Compared with N0 treatment, soil water content in 0-200 cm soil depth was decreased by nitrogen applied during each growth period under humid, dry and normal years. The nitrogen fertilizer application increased ET by 4.6%-14.6%, 6.0%-8.6% and 2.2%-9.5%, increased WUE by 20.7%-39.8%, 4.7%-33.3%, 13.1%-35.4%, increased yield by 7.1%-28.1%, 1.5%-34.1%, 8.5%-28.9%, and increased PC by 5.6%-10.4%, 10.1%-17.7% and 8.5%-15.6%, respectively. (3) The effects of nitrogen rates on grain yield and protein yield followed a quadratic curve relationship, and the fitting equation showed that the optimal nitrogen application rates for stable yield and quality of winter wheat were 189-202, 116-124 and 161-174 kg·hm-2 in humid, dry and normal years, respectively. 【Conclusion】On the whole, the best nitrogen application schemes were 189-202, 116-124 and 161-174 kg·hm-2 in humid, dry and normal years, respectively. And the management model of “nitrogen applying according to rain” was adopted, which was “the amount of basic nitrogen fertilizer was determined by SWSs, while the top dressing of nitrogen fertilizer was determined by rainfall from sowing to jointing stage”. The model could not only meet the requirements of stable yield and high quality of winter wheat, but also ensure water high-efficient use.

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