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Response of Biomass and Nutrient Competition Between Oilseed Rape and Weed to the Rate of N, P and K Fertilizer SHENG QianNan, YU XiaoHong, ZHOU Xiong, TIAN GuiSheng, WU HaiYa, GENG GuoTao, YAN JinYao, LI Jing, REN Tao, LU JianWei Scientia Agricultura Sinica    2023, 56 (3): 481-489.   DOI: 10.3864/j.issn.0578-1752.2023.03.007 Abstract （256）   HTML （41）    PDF （577KB）（153）       Knowledge map    Save 【Objective】 Weed is one of the important factors limiting the high yield of oilseed rape. The reasonable management of nutrients plays a key role in weed control. This study explored the effects of N, P and K fertilizer application rate on the biomass and nutrient competition between oilseed rape and weed under field conditions, so as to provide a basis for ecological grass control and sustainable agricultural development.【Method】 The field experiment was carried out in Wuxue City, Hubei Province, and a single factor experimental design was adopted. Four different rate gradients of N (0, 90, 180 and 270 kg N·hm-2, expressed by N0, N1, N2 and N3 respectively), P (0, 45, 90 and 135 kg P2O5·hm-2, expressed by P0, P1, P2 and P3 respectively), and K (0, 60, 120 and 180 kg K2O·hm-2, expressed by K0, K1, K2 and K3 respectively) were set. Oilseed rape yield, the biomass of oilseed rape and weed were investigated at the mature stage. The corresponding nutrient content was measured, the nutrient accumulation was calculated, and the nutrient competition relationship between oilseed rape and weed and its response to the rate of fertilizer were analyzed. 【Result】 Fertilization significantly increased oilseed rape yield, total shoot biomass and corresponding nutrient accumulation, among the three nutrients of N, P and K, the growth and nutrient accumulation of oilseed rape were the most sensitive to phosphorus deficiency. The yield of oilseed rape treated with N0, P0 and K0 were 560, 227 and 1 490 kg·hm-2 respectively, accounting for 18.2%, 7.5% and 50.1% of the highest yield of corresponding nutrient treatments (N3, P3 and K3), respectively. The variation trend of total shoot biomass with nutrient input was consistent with yield. The oilseed rape corresponding nutrient accumulation of N0, P0 and K0 treatments were 19.96, 0.88 and 26.21 kg·hm-2, respectively, which accounted for 12.24%, 3.72% and 22.26% of the highest nutrient accumulation of corresponding nutrient treatments, respectively. With the increasing of the application rate of three kinds of nutrient, the weed biomass and corresponding nutrient accumulation decreased (except the highest treatment P2 in the P fertilizer rate test), the weed biomass of N0, P0 and K0 treatments were 1 365, 3 060 and 1 535 kg·hm-2, respectively, which were the corresponding minimum weed biomass (N3, P2 and K3 treatment) 7.59 times, 5.19 times and 3.61 times, respectively; the corresponding nutrient accumulation of weed in N0, P0 and K0 treatments were 17.60, 1.91 and 9.38 kg·hm-2, respectively, which were 3.78 times, 1.54 times and 1.52 times higher than that in the corresponding minimum weed nutrient accumulation (N3, P2 and K3 treatment), respectively. Compared with P and K, the weed and oilseed rape had the greatest nutrient competitiveness to N, and the all N fertilizer treatment, the N content of weed was higher than that of oilseed rape. Fertilization increased the ratio of biomass and corresponding nutrient accumulation between oilseed rape and weed, except for no P application, the ratio of biomass and corresponding nutrient accumulation between oilseed rape and weed in other treatments was greater than 1, and this ratio increased with the increase of fertilization (except the highest treatment P2 in the P fertilizer rate test), which showed adequate nutrient supply can significantly improve the growth and nutrient absorption capacity, meanwhile it played a role in weed suppression.【Conclusion】 The harm degree of weed in winter oilseed rape field was controlled by nutrient supply, fertilization effectively made up for the deficiency that herbicide in the early stage could not completely control weed in the whole growth period. The sufficient application of N, P and K fertilizer could significantly reduce weed biomass and corresponding nutrient accumulation, under the experimental conditions, the response degree of three nutrients to the competitiveness between oilseed rape and weed was P>N>K. Table and Figures | Reference | Related Articles | Metrics

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Environmental Safety Risks in Agricultural Application of Effluents from Sugar Molasses-Based Fermentation Industries WANG XiaoBin, YAN Xiang, LI XiuYing, TU Cheng, SUN ZhaoKai Scientia Agricultura Sinica    2023, 56 (3): 490-507.   DOI: 10.3864/j.issn.0578-1752.2023.03.008 Abstract （489）   HTML （31）    PDF （714KB）（148）       Knowledge map    Save Sugar molasses is a by-product from sugar industries. The sugar molasses-based fermentation industries mainly refer to the fermentation industries using molasses from sugar mills as raw materials for alcohol or yeast fermentation. A large volume of effluents can be produced in the process of sugar molasses-based alcohol or yeast fermentation. Considering the possibility of resource utilization with such effluents, many sugar-producing countries (such as Brazil, India, and China) use the effluents for crop irrigation and fertilization or soil remediation directly into the farmlands by waste disposal methods. Because the effluents from sugar molasses-based fermentation industries are both high concentration organic wastewater, and heavy metal-polluted wastewater, which are difficult to be treated. With the long-term disposal of such effluents into the farmlands in some sugar-producing countries, the problems about ecological environment pollution in soil-crop-water systems are increasingly exposed. At present, some fertilizer production enterprises in China use such effluents as raw materials to produce organic water-soluble fertilizers (accounting for 32%), but the long-term research and monitoring data about environmental safety risks for agricultural application of the effluents from sugar molasses-based fermentation industries are still lack. This paper collected the relevant scientific research literatures since 1980 on the pollution characteristics of the effluents from sugar molasses-based fermentation industries, and their environmental impacts on agricultural application. Through the investigation and review on the relevant research data, this paper evaluated the environmental safety risks for agricultural application of the effluents from sugar molasses-based fermentation industries: (1) Such effluents were at a risk of seriously exceeding the limits for water quality standards, and a risk of ecotoxicity to plants. For example, such effluents had strong acidity, and high salinity, and contained not only high load organic pollutants, but also several heavy metals including 5 heavy metals (As, Hg, Cd, Pb and Cr), as well as other pollutants (such as Mn, Cu, Zn, Ni and Se, etc.). The concentrations of these pollutants mostly exceeded the limits of the Standards for Irrigation Water Quality (GB 5084—2021). (2) Such effluents for agricultural application were at a risk of farmland pollution. The concentrations of pollutants (such as Cu, Cd, Cr, Zn, Ni, Mn, Pb and Cl) detected from the soil samples irrigated with such effluents were about 10-641 times higher than those in the control soil. (3) Such effluents for agricultural application were at a safety risk of agricultural products. The concentrations of pollutants (such as Cu, Cd, Cr, Zn, Ni, Mn and Pb) detected in the grains of crops (wheat and mustard) irrigated with such effluents were about 3-12 times higher than those in the control crops, in which all the pollutants detected in the crops irrigated with such effluents exceeded both the allowable limits specified by FAO/WHO, but also the Maximum Levels of Contaminants in Food (GB 2762—2017) specified by China. In view of the issue of environmental safety risks for agricultural application of such effluents, therefore, it is necessary to strengthen the quality detection and risk control on the organic water-soluble fertilizer products with such effluents as raw material, to enable the safety of effluent utilization in agriculture. Table and Figures | Reference | Related Articles | Metrics

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Vertical Distribution of Vegetation Roots and Its Influence on Soil Erosion Resistance of Gully Heads on the Gullied Loess Plateau LOU YiBao,KANG HongLiang,WANG WenLong,SHA XiaoYan,FENG LanQian,NIE HuiYing,SHI QianHua Scientia Agricultura Sinica    2023, 56 (1): 90-103.   DOI: 10.3864/j.issn.0578-1752.2023.01.007 Abstract （244）   HTML （34）    PDF （1439KB）（99）       Knowledge map    Save 【Objective】The vertical distribution of gully vegetation root system and its effect on soil erosion resistance were explored, so as to provide a theoretical basis for optimizing the allocation of vegetation measures in gully erosion control. 【Method】 In this paper, the gully heads covered with different vegetation (weeds (farmland), Agropyron cristatum, Artemisia gmelinii, and Medicago sativa) were taken as the research object. The scouring experiment of undisturbed soils was carried out to determine the soil anti-scouribility. Moreover, the root characteristics and mechanical and physiochemical properties of root-soil complex were measured using root scanner and ZJ series strain controlled direct shear test apparatus, and so on, respectively. 【Result】(1) The root distribution characteristics at the gully head varied among different vegetation types. Agropyron cristatum had the greatest root characteristic indexes (root weight density, root length density, root surface area density, and root volume density), followed by alfalfa, Artemisia, and weeds in farmland. In addition, the root indexes in the gully head soil of farmland decreased with the deepening of soil layer, while those of Agropyron cristatum, Artemisia gmelinii and Medicago sativa firstly decreased and then increased with the deepening of soil layer. Furthermore, the roots with the diameter of <0.5 mm dominated in the root system of each vegetation. (2) The variability of soil bulk density among different vegetation type was low, ranging from 1.17 g·cm-3 to 1.37 g·cm-3. The contents of >0.25 mm water-stable aggregates of farmland and Agropyron cristatum land were higher than that of Artemisia gmelinii land and Medicago sativa land. (3) The average soil cohesions of gully heads under different vegetation types were as follows: 12.75 kPa for Medicago sativa land, 9.05 kPa for Agropyron cristatum land, 8.60 kPa for Artemisia gmelinii land, and 7.25 kPa for farmland, respectively. Additionally, the soil cohesion of the farmland, Agropyron cristatum land, and Medicago sativa land decreased first and then increased with the deepening of soil layer, while that of Artemisia gmelinii land showed a decreasing trend in the depth of soil. (4) The average anti-scouribility coefficients of 0-100 cm soil at the gully head under different vegetation types were as follows: 39.31 L·g-1 for Medicago sativa land, 25.49 L·g-1 for Agropyron cristatum land, > 22.39 L·g-1 for farmland and 14.75 L·g-1 for Artemisia gmelinii land. Moreover, the soil anti-scouribility coefficient of the 0-20 cm soil layer, varying between 34.91 and 53.30 L·g-1, was larger than that of the lower soil layers. 【Conclusion】 The combination of plants with tap roots and the plants with fibrous roots was suggested for the control of gully head erosion, and the results provided a theoretical basis for the research of gully headcut erosion and gully erosion control. Table and Figures | Reference | Related Articles | Metrics

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Effects of Straw Returning and Nitrogen Fertilizer Types on Summer Maize Yield and Soil Ammonia Volatilization Under Future Climate Change ZHAO ZhengXin,WANG XiaoYun,TIAN YaJie,WANG Rui,PENG Qing,CAI HuanJie Scientia Agricultura Sinica    2023, 56 (1): 104-117.   DOI: 10.3864/j.issn.0578-1752.2023.01.008 Abstract （389）   HTML （40）    PDF （705KB）（185）       Knowledge map    Save 【Objective】 Returning straw to the field and applying nitrogen fertilizer can increase crop productivity. However, under the conditions of climate change, the different management measures have great uncertainty in the nitrogen utilization of summer maize farmland. It is very important to clarify the impact of straw returning and nitrogen fertilizer types on summer maize yield and soil ammonia volatilization under future climate conditions. 【Method】 This study used the DNDC model to predict the impact of returning straw to the field and different types of nitrogen fertilizers on summer maize yield and soil ammonia volatilization accumulation in Guanzhong area under different scenarios in the future. Through the verification of field soil temperature, moisture, yield and soil ammonia volatilization test data, the DNDC model could simulate crop yields and soil ammonia volatilization accumulations under different treatments under the future climate conditions well. 【Result】Both simulation and actual measurement results showed that returning straw to the field increased summer maize yields and promoted soil ammonia volatilization under the current climate conditions. Compared with ordinary urea, slow-release fertilizers had no significant effect on summer maize yield but would significantly reduce soil ammonia volatilization accumulation. Sensitivity analysis showed that both crop yield and soil ammonia volatilization accumulation were the most sensitive to nitrogen application. Under the RCP4.5 emission scenario, the single application of stable nitrogen fertilizer (NF1) treatment and single application of urea (NF2) treatment significantly reduced the summer maize yield in 2050s-2090s and 2070s-2090s, respectively. Both the treatment of straw combined with stable nitrogen fertilizer (SF1) and the treatment of straw combined with urea (SF2) significant increased summer maize yield in 2050s-2090s; under the RCP8.5 emission scenario, NF1 significantly reduced the summer maize yield from 2070s to 2090s, and NF2 showed no significant change. The summer maize yields under SF1 and SF2 were increased significantly from 2050s to 2090s. For NF1 under the RCP4.5 emission scenario in 2050s-2090s and under the RCP8.5 emission scenario 2030s-2090s, the soil ammonia volatilization accumulation significantly increased compared with current climate conditions; for the remaining treatments, the cumulative amount of soil ammonia volatilization in future periods under different emission scenarios would be significantly reduce compared with current climatic conditions. 【Conclusion】The DNDC forecast results showed that under the climate conditions of rising temperature and CO2 concentration and changing precipitation in the Guanzhong area in the future, the returning straw to the field and applying stable nitrogen fertilizer would significantly increase the summer maize yield and reduce the accumulation of ammonia volatilization in the soil, and it was the best high-yield and emission-reducing farmland management plan. This research provided a theoretical basis for coping with climate change and the rational use of straw and nitrogen fertilizer. Table and Figures | Reference | Related Articles | Metrics

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Spatial Characteristic and Its Factors of Nitrogen Surplus of Crop and Livestock Production in the Core Area of the Baiyangdian Basin ZHAO HaiXuan,ZHANG YiTao,LI WenChao,MA WenQi,ZHAI LiMei,JU XueHai,CHEN HanTing,KANG Rui,SUN ZhiMei,XI Bin,LIU HongBin Scientia Agricultura Sinica    2023, 56 (1): 118-128.   DOI: 10.3864/j.issn.0578-1752.2023.01.009 Abstract （220）   HTML （29）    PDF （2876KB）（109）       Knowledge map    Save 【Objective】 The nitrogen surplus caused by excessive nitrogen input of crop and livestock production is the major source of pollution load in surface waterbody. The spatial differentiation characteristics of agricultural unused nitrogen were quantified in this study, so as to provide a basis for the zoning management of nitrogen and the effective management of agricultural nitrogen source in the river basin. 【Method】This study was conducted in Baoding, the central area of the Baiyangdian Basin. The nitrogen input and output of the crop and livestock production system were analyzed in all counties of Baoding in 2016. The nitrogen surplus in the crop production system was defined as the differential value between each input item (chemical fertilizer, organic fertilizer, atmospheric dry and wet settlement, irrigation water, seeds, non-symbiotic nitrogen fixation and straw returning to the field) and the output item (crop grain and straw); the nitrogen surplus in livestock production system was defined as the differential value between the amount of manure and the amount of organic fertilizer; and the nitrogen surplus in the agriculture and animal husbandry was defined as the sum of crop production system and livestock production system. 【Result】(1) The level of nitrogen surplus in crop production was ranging from 90.27 to 581.73 kg·hm-2, with the lowest value in Dingxing District and the largest value in Mancheng District. Vegetables contributed to the most nitrogen surplus of crop production (31.3%), following by fruit trees (29.0%), wheat (27.8%), and maize (11.9%). Fertilizer was the primary source of nitrogen surplus (61.8%), following by organic fertilizer (16.8%), straw return to the field (8.9%), atmospheric settlement (5.2%), irrigation (3.4%), non-symbiotic nitrogen fixation (3.0%), and seeds (0.9%). (2) The nitrogen surplus level of livestock production was ranging from 0.06×104 t to 2.48×104 t with the lowest value in Lianchi District and the highest value in Xushui Distrct. Beef cattle accounted for 71.0% of the total nitrogen surplus of livestock production. (3) The unused nitrogen level in the agricultural and animal husbandry system was between 0.43×104 t and 4.97×104 t, among which the unused nitrogen amount was the highest in the Xushui area. In farming systems, farming was the main source of nitrogen (55.8% of unused nitrogen). 【Conclusion】The nitrogen unused space varied significantly in Baoding counties, the core area of Baiyangdian Basin, and the highest nitrogen unused in Xushui District was 10.4 times that in Jingxiu District. The largest contribution to the amount of unused nitrogen in the crop and livestock production is the crop production, of which vegetable production is the most important industry. Table and Figures | Reference | Related Articles | Metrics

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Effects of Reducing Nitrogen Application Rate on the Yields of Three Major Cereals in China DU WenTing,LEI XiaoXiao,LU HuiYu,WANG YunFeng,XU JiaXing,LUO CaiXia,ZHANG ShuLan Scientia Agricultura Sinica    2022, 55 (24): 4863-4878.   DOI: 10.3864/j.issn.0578-1752.2022.24.007 Abstract （423）   HTML （49）    PDF （624KB）（271）       Knowledge map    Save 【Objective】 The present study investigated the effects of reducing nitrogen application rate on the yields of three major cereals in China and its relationship with soil and other factors, so as to clarify the feasibility of reducing nitrogen application. 【Method】 90 published papers from 2010 to 2021 were collected and analyzed the effects of different nitrogen fertilizer reduction ratios on yield, and its relationship with planting systems and different conditions (fertilizer type, soil organic matter content, total nitrogen, soil pH, and water management). 【Result】 Compared with conventional fertilization rate, 0-40% nitrogen reduction did not significantly reduce the yield of rice, 0-30% nitrogen reduction did not significantly affect the yields of wheat and maize, when the nitrogen reduction was 30%-40%, the yield of wheat and maize significantly reduced by 6.1% and 5.4%, respectively. The yield level without nitrogen input area did not significantly affect crop yield of the three cereals following reduction of nitrogen rate. When soil total nitrogen was more than 2 g·kg-1, rice yield with reduced nitrogen application (6.5 t·hm-2) was significantly higher than that with conventional nitrogen application (6.3 t·hm-2); when total nitrogen was more than 1 g·kg-1, wheat yield with reduced nitrogen application (6.9 t·hm-2) was significantly lower than that with conventional nitrogen application (7.4 t·hm-2); when total nitrogen was more than 1.5 g·kg-1, maize yield with reduced nitrogen application (8.8 t·hm-2) was significantly lower than that with conventional nitrogen application (9.1 t·hm-2). When soil organic matter content was more than 30 g·kg-1, rice yield with reduced nitrogen application (6.9 t·hm-2) was significantly higher than that with conventional nitrogen application (6.7 t·hm-2), but soil organic matter content were 10-20 g·kg-1 and more than 20 g·kg-1, the reducing nitrogen application significantly reduced wheat yield. When soil pH was lower than 6.5, rice yield with reduced nitrogen application (6.6 t·hm-2) was significantly higher than that with conventional nitrogen application (6.4 t·hm-2). Wheat yield (6.6 t·hm-2) with reducing nitrogen application under single cropping was significantly higher than that with conventional nitrogen application (5.9 t·hm-2); maize yield (8.9 t·hm-2) with reducing nitrogen application under double cropping was significantly lower than that with conventional nitrogen application (9.1 t·hm-2). Based on common fertilizer, wheat yield with reducing nitrogen application (6.8 t·hm-2) was significantly lower than that with conventional nitrogen application (7.1 t·hm-2). Under rainfed, wheat yield with reducing nitrogen application (5.9 t·hm-2) was significantly lower than that with conventional nitrogen application (6.6 t·hm-2). 【Conclusion】 The yield of three major cereals in China can be maintained by reducing conventional nitrogen application rate by 30% although crop yield varied to certain extent with soil properties and management measures. Therefore, the reduced application of nitrogen fertilizer needed to be adjusted according to soil properties and management practices to achieve high yield and high nitrogen efficiency. Table and Figures | Reference | Related Articles | Metrics

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Provincial Agricultural Ecological Efficiency and Its Influencing Factors in China from the Perspective of Grey Water Footprint DENG YuanJian,CHAO Bo Scientia Agricultura Sinica    2022, 55 (24): 4879-4894.   DOI: 10.3864/j.issn.0578-1752.2022.24.008 Abstract （440）   HTML （40）    PDF （617KB）（86）       Knowledge map    Save 【Objective】This paper evaluated Chinese provincial agricultural ecological efficiency from the perspective of gray water footprint, revealed the spatial distribution characteristics of agricultural ecological efficiency, analyzed the main factors affecting agricultural ecological efficiency, and put forward policy suggestions to improve Chinese provincial agricultural ecological efficiency. 【Method】Based on the provincial panel data of China from 2000 to 2019, this paper comprehensively evaluated the agricultural ecological efficiency of Chinese provinces with the super efficiency SBM model considering the unexpected output, and used the spatial Dobbin model to analyze the spatial differences and influencing factors of agricultural ecological efficiency. 【Result】(1) In general, the agricultural grey water footprint showed a downward trend, but in some provinces (cities and districts), it showed an upward trend. From the ranking of grey water footprint from low to high, it could be seen that the provinces (cities and districts) in the forefront (i.e. with less grey water footprint) had a high level of economic development or a relatively low proportion of agricultural output value; the provinces (cities and districts) in the rear row (i.e. with more grey water footprint) had low economic development level or high agricultural output value. (2) During the observation period, the agricultural ecological efficiency fluctuated greatly in some years in the stable trend, and the average difference among provinces (cities and districts) was obvious and the distribution was extremely unbalanced. (3) Economic development level, fiscal expenditure for supporting agriculture, technological progress, agricultural disaster rate, planting structure and other factors had different impacts on Chinese agricultural ecological efficiency. With the improvement of both economic development level and people's living quality, both agricultural operators and consumers paid more attention to the protection of agricultural ecological environment and the quality of agricultural products, which have improved the level of regional agricultural ecological efficiency to a certain extent. But the pollution caused by regional economic and social development might also have a negative impact on agricultural ecological efficiency. Most of the financial support for agriculture was used to subsidize production links, such as pesticides, chemical fertilizers, and agricultural machinery. Although the agricultural production conditions have been improved and the agricultural economic productivity and efficiency have been improved, the improvement of agricultural ecological efficiency was not significant. The development of technology was very important in the agricultural production process, and the proper use of it would improve the agricultural ecological efficiency. The estimated results of agricultural disaster rate failed to pass the significance test, which might be because the expansion of agricultural disaster area would lead to the decline of agricultural ecological efficiency, but the annual disaster situation was not regular. The coefficient of planting structure was negative, which had a negative impact on agricultural production efficiency. This might be due to the high proportion of grain crop planting area in the total planting area of crops, and the high consumption of nitrogen fertilizer. 【Conclusion】As the evolution trend and difference of agricultural gray water footprint in various provinces (cities and districts) in China were obvious, the overall level of agricultural ecological efficiency was not high, and various factors have different impacts on agricultural ecological efficiency, it was necessary to improve the governance mechanism of agricultural gray water footprint; optimize the agricultural industrial structure and establish a compensation mechanism for agricultural water resources protection based on gray water footprint; improve the ways and policies of financial support for agriculture, and guide business entities to actively improve agricultural ecological efficiency. Table and Figures | Reference | Related Articles | Metrics

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Effects of Straw Returning and Potassium Fertilizer on Soil Aggregate and Potassium Distribution Under Rapeseed-Rice Rotation LIU ShuJun,LI DongChu,HUANG Jing,LIU LiSheng,WU Ding,LI ZhaoQuan,WU YuanFan,ZHANG HuiMin Scientia Agricultura Sinica    2022, 55 (23): 4651-4663.   DOI: 10.3864/j.issn.0578-1752.2022.23.007 Abstract （306）   HTML （50）    PDF （1016KB）（113）       Knowledge map    Save 【Objective】 The study aimed to explore effects of different fertilization on paddy soil aggregate characteristics and potassium distribution under rapeseed-rice rotation and winter fallow by the located experiment test. It was hoped that the study would provide a basis for the sustainable utilization of potassium resources in paddy-upland rotation areas of Southern China. 【Method】 Based on the location experiment of potassium fertilizer in different rotation patterns started in 2016, five treatments were selected, including CK(F) (no fertilization and winter fallow), NPK(F) (NPK fertilizer and winter fallow), NPK(R) (NPK fertilizer and winter rapeseed), NPK (SR+R) (NPK fertilizer with rice straw returning and winter rapeseed), and NP50%K (SR+R) (50% reduction of K fertilizer with rice straw returning and winter rapeseed). The soil samples were collected from the 0-20 cm soil layer of each treatment after rape harvest of the third year for analysis of physical and chemical properties, such as soil aggregates distribution, and exchangeable and non-exchangeable potassium content variation in soil aggregates. The stability of soil aggregates and the distribution of potassium in aggregates were further investigated..【Result】 The soil aggregate fractions of all treatments was the highest in <0.053 mm. Compared with NPK(F), NPK(R) increased the proportion of aggregates of 1-2 mm, 0.5-1 mm and 0.25-0.5 mm by 26.2%-82.6% under the same fertilization treatment. Also the stability of soil aggregates was increased, the proportion of aggregates of >0.25 mm, mean weight diameter (MWD), and geometric mean diameter (GMD) were significantly increased by 30.6%, 31.2% and 82.0%, respectively. Under rapeseed-rice rotation, the proportion of aggregates of >2 mm was increased under NPK(SR+R), which was 69.7% higher than that under NPK(R). The exchangeable potassium content in soil aggregates decreased with decreasing particle size under all treatments. NPK(SR+R) significantly increased exchangeable potassium content in all aggregate fractions by 22.2%-46.0% compared with NPK(R) under rapeseed-rice rotation. NP50%K(SR+R) significantly reduced the exchangeable potassium content in aggregates of >0.5 mm by 19.4%-20.6% than NPK(SR+R). Compared with NPK(F), three fertilization treatments under rapeseed-rice rotation all reduced the non-exchangeable potassium content in aggregate fractions. Under all treatments, the contribution rate of different fractions of soil aggregates to the bulk soil in potassium was the highest in <0.053 mm. Compared with NPK(F), NPK(R) significantly increased the contribution rates of 1-2 mm and 0.5-1 mm aggregates to bulk soil in potassium by 82.6%, 52.1% (exchangeable potassium ) and 105.5%, 36.9% (non-exchangeable potassium), respectively.【Conclusion】 The rapeseed-rice rotation could increase MWD, GMD, macroaggregate proportion and the contribution rate of macroaggregate to the bulk soil in potassium and improve soil structure. Under this rotation pattern, the chemical fertilizer combined with rice straw returning could increase the exchangeable potassium content in all aggregate fractions, which improved the potassium supply in paddy soil. However, the rapeseed-rice rotation reduced the content of non-exchangeable potassium in soil aggregates due to high potassium demand, and the input of potassium fertilizer should be appropriately increased. Table and Figures | Reference | Related Articles | Metrics

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Carbon and Nitrogen Fixation Characteristics of Maize Root and Straw Residues in Brown Soil Under High and Low Fertility LI JiaYan,SUN LiangJie,MA Nan,WANG Feng,WANG JingKuan Scientia Agricultura Sinica    2022, 55 (23): 4664-4677.   DOI: 10.3864/j.issn.0578-1752.2022.23.008 Abstract （235）   HTML （30）    PDF （556KB）（91）       Knowledge map    Save 【Objective】 Straw returning to the field is one of important measures to increase soil carbon (C) fixation and to improve soil nutrient status. Studying the C and nitrogen (N) fixation characteristics of different parts of maize residues in the soil is of great significance for clarifying the C and N sequestration mechanism under straw returning. 【Method】 This study was based on the long-term experiment station of Shenyang Agricultural University. The soils treated with no fertilization and organic fertilizer combined with chemical fertilizers were collected as low fertility (LF) and high fertility (HF) soils, respectively, and combined with 13C and 15N double-labeled maize residues. Maize stalk and leaf part (S) as well as root part (R) are mixed with collected soils, respectively, and incubated at 25℃. In the experiment, the samples were taken on the 1st, 30th, 60th, 180th and 360th days to determine the total organic C (SOC), total N (TN) content, and their isotopic abundances, and to analyze C and N fixing dynamics of different parts of maize residues in the soil with different fertility levels..【Result】 Adding maize residues significantly increased soil SOC, and could still increase by 14.0% after one year. After adding maize residues, a small part of N in the soil system might be lost by denitrification, and both added N deriving from maize residues and native N in soil were contributed in the lost. Compared with the addition of root residues, the addition of straw residues was more conducive to retaining the added residual C and N, which had a stronger effect on stimulating the local C decomposition and N loss. In contrast, the root residues tended to be decomposed, while the native soil C and N were relatively protected. Although the fixation of added residual C in low-fertility soil was higher than that in high-fertility soil, the fixed added residual C presented a greater contribution to the promotion of C pool in the low-fertility soil. Under the treatment of residues addition, C/N and 13C/15N (representing residue-deriving C/N in the soil) in low-fertility soil were significantly higher than those in high-fertility soil. However, the results showed that 13C/15N was not the main factor limiting the decomposition and fixation of residues in low-fertility soil, which might be related to the distinctive soil microbial community favoring of utilizing the specific substrate under the long-term substrate selection..【Conclusion】 Adding maize residues from different parts of the soil could significantly increase soil carbon and nitrogen levels, but the immobilization strategies of new carbon/nitrogen in the residues and soil old carbon/nitrogen were different. The low-fertility soil had higher capacity to fix exogenous carbon and less fertility, and their fixation of residues in different parts was not affected by the limitation of C/N from exogenous residues in this study. Table and Figures | Reference | Related Articles | Metrics

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Net Anthropogenic Nitrogen Inputs and Its Influencing Factors in Three Typical Watersheds of China ZHANG TianPeng,YAN TieZhu,JIN PingZhong,LEI QiuLiang,LIAN HuiShu,LI Ying,LI XiaoHong,OU HuiPing,ZHOU JiaoGen,DU XinZhong,WU ShuXia,LIU HongBin Scientia Agricultura Sinica    2022, 55 (23): 4678-4687.   DOI: 10.3864/j.issn.0578-1752.2022.23.009 Abstract （320）   HTML （30）    PDF （2212KB）（83）       Knowledge map    Save 【Objective】 Net anthropogenic nitrogen input (NANI) is one of the important causes to non-point source pollution. In order to investigate the spatio-temporal characteristics and influencing factors of net anthropogenic nitrogen input, the key source areas were identified and the key sources in watersheds were analyzed, so as to provide data support for solving the problem of non-point source nitrogen pollution. 【Method】 Three watersheds were selected according to their characteristics, among which Xiangxi River watershed was a typical agriculture watershed, Erhai watershed was comprehensively promotion model of green agricultural development, and Taihu watershed was a typical urban centralized watershed. Based on the NANI model, the data was obtained through statistical yearbook and literature review to evaluate NANI of the three typical watersheds.【Result】 In terms of NANI intensity, the average value of NANI in the three typical watersheds was ranked as follows: Taihu watershed (13 241 kg·km-2·a-1), Xiangxi River watershed (2 183 kg·km-2·a-1), and Erhai watershed (1 582 kg·km-2·a-1). In terms of NANI sources, nitrogen application (Nfer) and food/feed nitrogen (Nim) were the largest sources of NANI, accounting for 58%-97%. The NANI contribution ranked in the order of nitrogen application, food/feed nitrogen input, nitrogen deposition input, and crop nitrogen fixation input. In terms of time, food/feed nitrogen input of Xiangxi River watershed decreased by 23 percentage points from 2010 to 2019, while nitrogen deposition increased by 34 percentage points. From 2010 to 2019, nitrogen application in NANI decreased by 86 percentage points in Erhai watershed. From 2010 to 2019, the input of food/feed nitrogen to NANI in Taihu watershed increased by 31 percentage points, while the input of crop nitrogen fixation and nitrogen deposition decreased by 14 and 12 percentage points, respectively. In terms of influencing factors, NANI was significantly correlated with urban population density in the three typical watersheds (P<0.05), and NANI increased with the increase of urban population density. The Xiangxi River watershed had a significant effect on the proportion of cultivated land and NANI fitting (P<0.05), but the Erhai watershed and Taihu watershed was not significant effect (P>0.05)..【Conclusion】 Zhaojun town, Xiakou town and Huangliang town in Xiangxi River watershed, Xiaguan town, Shangguan town and Fengyi town in Erhai watershed, and Zhangjiagang City, Xiucheng District in Jiaxing City, Gongshu District and Nanhui District in Taihu watershed were the key source areas of NANI. Fertilizer application was the main source of NANI in Xiangxi River watershed where is mainly agricultural. The input of food/feed nitrogen and fertilizer nitrogen were the main sources of NANI in Taihu watershed where is mainly urbanization. The green agricultural development model could significantly reduce net anthropogenic nitrogen input. Therefore, it was beneficial to control agricultural non-point source pollution by vigorously promoting agricultural green development measures and effectively reducing the input of feed and fertilizer in key source areas. Table and Figures | Reference | Related Articles | Metrics

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Characteristics of Phosphorus Fractions and Its Response to Soil Chemical Properties Under the Threshold Region of Olsen P in Black Soil QIN ZhenHan,WANG Qiong,ZHANG NaiYu,JIN YuWen,ZHANG ShuXiang Scientia Agricultura Sinica    2022, 55 (22): 4419-4432.   DOI: 10.3864/j.issn.0578-1752.2022.22.008 Abstract （359）   HTML （39）    PDF （649KB）（144）       Knowledge map    Save 【Objective】 Agronomic and environmental thresholds of Olsen phosphorus (P) are the most important parameters for soil P management, but the characteristics of phosphorus fractions under the different threshold regions are not clear. This research evaluated the characteristics of the P fraction under the different threshold regions of Olsen P and its influencing factors in black soils for enabling to understand the transformation process of soil P, so as to provide a reference for optimizing the Olsen-P management strategy and improving the efficiency of P resource utilization.【Method】9 Olsen P levels (11, 21, 31, 40, 57, 69, 128, 331, and 490 mg·kg-1) of agricultural fields plow layer (0-20 cm) soil samples were collected in Gongzhuling, Jilin Province. TIESSEN-Moir modified HEDLEY phosphorus classification method was used to classify soil inorganic phosphorus and organic phosphorus. The relationship between the phosphorus fractions and soil chemical properties, such as soil organic matter (SOM), C/P, Fe, and Al oxides, was also analyzed to clarify the characteristics of phosphorus fractions and the main controlling factors under the different threshold regions of soil Olsen P.【Result】The P pool was dominated by Pi, accounting for 71.25%-96.19%, with Po accounting for 3.81%-28.75%. When the Olsen P level was below the agronomic threshold (7.4-13 mg·kg-1), the proportion of liable P (LP) of 19.89% was the lowest in comparation with other P fractions. When the Olsen P level was below the environmental threshold (51.0-56.4 mg·kg-1), the proportion of medium active phosphorus (ML-P) and stable phosphorus (OP) is close, 36.03% and 35.49% respectively, both higher than the proportion of LP (28.48%). The highest proportion of LP (42.86%) was observed when the Olsen P level was above the environmental threshold. When the Olsen P level is higher than the environmental threshold, the content of LP and ML-P in the soil is significantly higher than that in the soil where the Olsen P level is lower than the environmental threshold, and the resin-P showed the greatest variation with Olsen P above and below the environmental threshold. The value of P activation coefficient (PAC), and the concentration of Mehlich-3 extractable aluminum (M3-Al), free Al oxide (Ald), organic-bound Fe, Al oxide (Fep, Alp), and amorphous Fe, Al oxide (Feo, Alo) increased significantly, while a significant decrease in C/P was observed with increasing Olsen P levels. The correlation analysis shows that when the Olsen P level was below the environmental threshold, the soil organic matter was positively and significantly correlated with the highly active inorganic P fractions (Resin-P, NaHCO3-Pi, NaOH-Pi) above the environmental threshold; when the Olsen P level was above the environmental threshold, Fep+Alp showed a strong positive correlation with each inorganic P fraction blow the environmental threshold. The redundancy analysis results showed that when the Olsen P level was below the environmental threshold, SOM and M3-Fe were the key factors for affecting the change of P fractions in black soils, explaining 50.2% and 24.1% of the total variation, respectively; when the Olsen P level was above the environmental threshold, Fep+Alp was the main factor influencing the change of P fractions, explaining 68.1% of the total variation.【Conclusion】 When the Olsen P level was below the agronomic threshold, the liable P accounted for the lowest proportion; however, which was the greatest proportion when the Olsen P level was above the environmental threshold. In addition, the Resin-P is the phosphorus fraction with the largest variation below and above the environmental threshold. SOM, M3-Fe, and Fep+Alp were the key factors affecting the change of P fractions below and above the environmental threshold, respectively. Table and Figures | Reference | Related Articles | Metrics

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Effects of Foliar-Spraying Selenium Coupled with Soil Moisture on the Yield and Quality of Tomato LIU Hao,PANG Jie,LI HuanHuan,QIANG XiaoMan,ZHANG YingYing,SONG JiaWen Scientia Agricultura Sinica    2022, 55 (22): 4433-4444.   DOI: 10.3864/j.issn.0578-1752.2022.22.009 Abstract （243）   HTML （48）    PDF （1026KB）（125）       Knowledge map    Save 【Objective】 Both exogenous selenium and soil moisture can affect crop growth and quality properties. It is very important to clarify the influences of exogenous selenium coupled with soil moisture on the tomato yield and quality, which maybe provide a theoretical basis on the water use for production of selenium-enriched tomato. 【Method】Three foliar-spraying selenium concentrations, such as 0 (S0), 5 (S5) and 10 mg·L-1 (S10), were considered with sodium selenite (Na2SeO3) as the selenium source by using pot experiment in this paper. Each selenium concentration was associated with two irrigation levels, which were scheduled to irrigate the crop as soon as the soil water moisture decreased to 50% (W1) and 75% (W2) of the field capacity, respectively. The effects of the different treatments on the selenium content, plant growth, yield and quality of tomato were studied.【Result】The different soil moistures had no significant impact on the selenium contents in soil, leaf and fruit (P>0.05). Although the different selenium concentrations had no marked influence on the soil selenium content for each irrigation level, the increasing selenium concentration led to an significant (P<0.01) increase in selenium content of leaves and fruits. Compared with S0 over the two irrigation levels, selenium-treated fruits increased the average selenium content with 2-4 fold. Drought stress significantly reduced plant height and stem diameter. The foliar-spraying selenium moderately alleviated the inhibition effect on plant height when crop suffered drought stress, whlie no significant effect was found on stem diameter. The drought stress gave a significant reduction in yield by 39.5% compared with the sufficient soil water applied. The foliar-spraying selenium had an increase in fruit number, but tended to decrease fruit weight under the drought stress conditions, thus no noticeable difference in yield was investigated between different foliar-spraying selenium. Compared with the sufficient soil water applied, the drought stress gave a significant increase in soluble sugar (SSC), organic acid (OA), vitamin C, and total soluble solid content (TSS) by 28.7%, 24.3%, 18.7%, and 24.0%, respectively. The foliar-spraying selenium improved SSC, whereas there was no noticeable difference in SSC between different selenium concentrations when the soil moisture was the same. Foliar-spraying selenium significantly increased OA except for S5W2 treatment compared with the control, thus S5W2 had the highest sugar-acid ratio (SAR), while the lowest SAR was observed in S0W2 treatment. There was no marked effect of foliar-spraying selenium on TSS under sufficient soil water applied conditions, however, the TSS was increased firstly and then decreased with selenium concentration increasing under drought stress, indicating that a further increase in selenium concentration from 5 mg·L-1 did not give a noticeable increase in fruit quality. 【Conclusion】 The coupling effect of foliar-spraying selenium and soil moisture on tomato quality was obvious. The spraying sodium selenite at 5 mg·L-1 significantly increased SSC and TSS and thereby improved nutritional quality of fruit when the plant suffered drought stress, but promoted flavor quality of fruits with no yield decreasing and thereby achieved stable yield and high quality when the soil moisture applied was sufficient. Table and Figures | Reference | Related Articles | Metrics

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Effect of CO2 Like Fertilization on Rice Growth by HCO3- in Biogas Slurry WAN HuaQin,GU Xu,HE HongMei,TANG YiFan,SHEN JianHua,HAN JianGang,ZHU YongLi Scientia Agricultura Sinica    2022, 55 (22): 4445-4457.   DOI: 10.3864/j.issn.0578-1752.2022.22.010 Abstract （176）   HTML （30）    PDF （1455KB）（72）       Knowledge map    Save 【Objective】 Biogas slurry is rich in nitrogen (N), which is the basis of its farmland utilization. However, it also contains a large amount of HCO3-. In this study, the conversion of HCO3- in biogas slurry and its effect on rice growth were investigated, in order to provide a new theoretical basis for replacing chemical fertilizer with biogas slurry, reducing the amount of chemical fertilizer, and whether biogas slurry could be utilized as resources. 【Method】Four treatments, including biogas slurry (BS), biogas slurry (BS-B), deionized water plus HCO3- (W+B) and deionized water (W), were set up in this paper. Using 13C labeling technology, the characteristics of CO2 release were observed through pot experiment at Rice Seedling Stage, and the photosynthetic rate, intercellular CO2 concentration, dry and fresh weight, plant height, overlying water and soil pH, and HCO3- and NH4+ contents were analyzed. 【Result】(1) Under BS treatment, CO2 release rates ranged from 9.55 to 38.07 mg·kg-1·h-1, with a net cumulative release of 4 654.06 mg·kg-1. Under BS-B treatment, the CO2 release rates ranged from 4.55 to 17.25 mg·kg-1·h-1, and the net cumulative release was 780.68 mg·kg-1. Under W+B treatment, the CO2 release rate was 3.93-26.33 mg·kg-1·h-1, and the net cumulative release was 1 274.07 mg·kg-1. Under W treatment, the CO2 release rate was 3.22-11.90 mg·kg-1·h-1, and the cumulative release amount was 2 265.20 mg·kg-1. Under BS treatment, the average CO2 release rate was 4.18 times and 2.44 times of BS?B and W+B, respectively, and the net cumulative CO2 release was 5.96 times and 3.65 times of BS-B and W+B, respectively, which were significantly higher than those under BS?B and W+B treatments. At the same time, the net cumulative release under BS treatment was greater than the sum of the two treatments (BS-B) + (W+B), and HCO3- had a synergistic effect with other components in biogas slurry on CO2 release. (2) The net cumulative release of 13CO2 under BS treatment was 32.87 mg·kg-1, accounted for 0.71% of the net cumulative release of CO2 in soil-rice system. The net cumulative release of 13CO2 under W+B treatment was 13.18 mg·kg-1. In comparison, the net cumulative release amount of 13CO2 under BS treatment was significantly higher than that under W+B treatment (P<0.05), indicated that other components in biogas slurry promoted the conversion of HCO3- to CO2. (3) The net photosynthetic rate of BS and BS?B treatments in the first 12 h was significantly higher than that under W+B and W treatments. After the addition of culture medium, the net photosynthetic rate under BS treatment was significantly higher than that under BS?B treatment at 2-7 d, and was significantly higher than that under W+B treatment during the whole culture period (P<0.05). HCO3- in biogas slurry significantly improved the photosynthesis of rice leaves. In comparison, the intercellular CO2 concentration was significantly lower than that of the other three treatments 5 days before BS treatment. Rice plant height and fresh weight under BS and BS-B treatments were significantly higher than those under W+B and W treatments (P<0.05), and there was no significant difference in dry weight among the four treatments. (4) The fixed 13CO2 content of rice seedlings treated by BS was 4.05 g·kg-1, and the utilization rate of marker HCO3- was 18.54%. The fixed amount of 13CO2 in W+B treatment was 3.29 g·kg-1 and the H13CO3- utilization rate was 14.20%. The 13CO2 of H13CO3- promoted the photosynthesis of rice and was beneficial to the growth of rice. (5) The release rates of CO2 and 13CO2 under BS and W+B treatments were significantly correlated with overlying water and soil HCO3- content and pH. At the same time, the photosynthetic rate of rice under BS and W+B treatments was significantly positively correlated with HCO3- content in soil. 【Conclusion】 When biogas slurry was returned to the field, a large amount of HCO3- transformation significantly promoted the release of CO2, which was beneficial to rice photosynthesis. Soil HCO3- content and soil pH value were important factors for affecting CO2 release and rice photosynthesis. At the same time, the rice had a higher utilization rate of HCO3- in biogas slurry, and HCO3- in biogas slurry had obvious CO2-like fertilization effect. Table and Figures | Reference | Related Articles | Metrics

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Research on Spatial Distribution of Soil Texture in Southern Ningxia Based on Machine Learning SHEN Zhe,ZHANG RenLian,LONG HuaiYu,XU AiGuo Scientia Agricultura Sinica    2022, 55 (15): 2961-2972.   DOI: 10.3864/j.issn.0578-1752.2022.15.008 Abstract （277）   HTML （34）    PDF （2712KB）（102）       Knowledge map    Save 【Objective】Based on historical soil data, this paper studied the spatial variability of soil texture and its relationship with environmental factors in southern Ningxia by using machine learning.【Method】Classification and regression tree (CART), random forest (RF) and traditional statistical methods were used to explore the main environmental factors that affected the soil texture types and predict the spatial distribution of soil texture types in southern Ningxia, based on 428 soil profiles from the second soil survey in the 1980s, combined with topographic factors, soil types, and normalized vegetation index. The accuracy of the models were verified by the validating set of soil profiles and the soil samples in Haiyuan County, Ningxia.【Result】(1)The accuracy rates of RF and CART on the soil texture type of the verification set of soil profiles were 62.36% and 55.29%, respectively; the area under the receiver operating characteristic (ROC) curve of them (area under roc curve, AUC) were 0.7515 and 0.6933, respectively; the accuracy rates of them on soil samples in Haiyuan County were 54.10% and 48.36%, respectively; the AUC of them were 0.6599 and 0.5981 respectively. (2) Soil type (ST) was the most important predictor variable, followed by elevation (Ele). The higher elevation was, the heavier the soil texture was. The effects of wind exposition index (WEI) and slope (Slo) on soil texture were lower. (3)The results predicted by two methods showed a spatial distribution trend that the soil texture was heavy in the southern area but light in the northern area of southern Ningxia.【Conclusion】The prediction accuracy of RF for soil texture type in southern Ningxia was higher than CART. Making full use of historical data, combined with field sampling, could meet the accuracy requirements of digital mapping. In the loess region, soil types and elevation were the environmental factors which had strong correlation with spatial variation of soil texture. Table and Figures | Reference | Related Articles | Metrics

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Quantitative Study on Effective Accumulated Temperature and Dry Matter and Nitrogen Accumulation of Summer Maize Under Different Nitrogen Supply Levels CHEN Yang,XU MengZe,WANG YuHong,BAI YouLu,LU YanLi,WANG Lei Scientia Agricultura Sinica    2022, 55 (15): 2973-2987.   DOI: 10.3864/j.issn.0578-1752.2022.15.009 Abstract （275）   HTML （38）    PDF （695KB）（125）       Knowledge map    Save 【Objective】This paper explored the dynamic prediction model and characteristic parameters of dry matter and nitrogen accumulation in summer maize with different nitrogen supply levels based on effective accumulated temperature, in order to provide a theoretical basis for using effective accumulated temperature to predict summer maize dry matter and nitrogen accumulation.【Method】This study was based on a two-year field experiment in Langfang, Hebei Province (2019-2020), using Zhengdan 958 as the test material, and using the normalization method to fit the dry matter and nitrogen accumulation of summer maize with different nitrogen supply levels through model screening. Based on the normalized Gompertz model of effective accumulated temperature after sowing, and using the growth rate curve and its characteristic parameters, the dry matter and nitrogen accumulation characteristics of summer maize were quantitatively analyzed.【Result】(1) Under the experimental conditions, when the amount of phosphorus and potassium fertilizer was appropriate, the maximum dry matter and nitrogen accumulation of summer maize continued to increase with the increase of nitrogen application rate. (2) The normalized Gompertz model of summer maize dry matter and nitrogen accumulation established with effective accumulated temperature as the independent variable had the good biological significance. The coefficients of determination of the equation were 0.9962-0.9988 and 0.9887-0.9922, respectively. Using the second-year data for model verification, the correlation coefficients of the simulated and measured values were 0.9933-0.9959 and 0.9830-0.9923, and the standardized root mean square errors were 6.64%-16.86% and 7.31%-12.68%, respectively. The prediction effect was good. (3) The growth rate of dry matter and nitrogen accumulation of summer maize at different nitrogen supply levels all showed a “single peak curve”, and its change was closely related to the nitrogen supply level. The performance between treatments was: under the condition of moderate fertilization, the growth rate curve had the characteristics of fast rising and falling, and the growth rate curve of weight loss treatment had the characteristics of slow rising and falling. (4) The effective accumulated temperature ranges of dry matter and nitrogen accumulation during the rapid increase period of summer maize after sowing were 709.35-1 722.54 and 482.50-1 507.61 ℃·d, respectively, and the effective accumulated temperature required for the maximum rate showed that nitrogen accumulation (995.05 ℃·d) was less than dry matter accumulation (1 215.94 ℃·d). Nitrogen supply level obviously affected the accumulation of dry matter and nitrogen in summer maize to enter the accumulation temperature required for the rapid increase period, the accumulated temperature required for the slow increase period, the accumulated temperature required for the maximum increase rate, the maximum increase rate, and the average increase rate during the rapid increase period. Compared with nitrogen fertilizer treatment, the effective accumulated temperature required for summer maize to enter each critical period was significantly reduced, and the growth rate during the critical period increased significantly.【Conclusion】The normalized Gompertz model could not only simulate and predict the dynamic changes of summer maize dry matter and nitrogen accumulation with effective accumulated temperature with different nitrogen supply levels, but also clarify the quantitative relationship between effective accumulated temperature and dry matter and nitrogen accumulation. The Gompertz model based on effective accumulated temperature could be used to predict crop growth and optimal fertilization period, and had strong application value.. Table and Figures | Reference | Related Articles | Metrics

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Effects of Partial Substitution of Chemical Fertilizer by Organic Fertilizer on Ponkan Growth and Quality as well as Soil Properties WAN LianJie,HE Man,LI JunJie,TIAN Yang,ZHANG Ji,ZHENG YongQiang,LÜ Qiang,XIE RangJin,MA YanYan,DENG Lie,YI ShiLai Scientia Agricultura Sinica    2022, 55 (15): 2988-3001.   DOI: 10.3864/j.issn.0578-1752.2022.15.010 Abstract （308）   HTML （49）    PDF （581KB）（161）       Knowledge map    Save 【Objective】Through systematical research focused on the effects of different organic fertilizer substitutions on growth, yield and quality, physicochemical properties of soil and orchard environment of ponkan under equal nutrient, it could be provided the suitable amount of organic fertilizer substitution for the scientific application of organic fertilizer and theoretical basis for enlarging high quality of citrus.【Method】The 15-year-old Taiwan ponkan grafted on Poncirus trifoliata (L.) was used as experimental materials. Six different treatments were performed, including no fertilization (CK), single chemical fertilizer (FP), substitution 10% of nitrogen (N), 25% of phosphorus (P), 18% of potassium (K) (T1), substitution 15% of N, 38% of P, 27% of K (T2), substitution 20% of N, 51% of P, 36% of K (T3), substitution 30% of N, 76% of P, 54% of K (T4). The nitrogen, phosphorus and potassium nutrient content of treatment except CK was consistent with research into the effects of different organic fertilizer substitution on the accumulation of citrus branches, leaves and fruits of dry matter in that year, fruit yield and quality, physicochemical properties of soil, carbon emissions and nitrogen leaching in 2019 and 2020.【Result】(1) The two-year’s research showed similar trends in growth indicators, such as spring and autumn leaf, fruit and flower of dry matter, with the growth of organic fertilizer substitution showing a trend of first rise and then decrease. On the whole, T1 and T2 treatment were beneficial to accumulate ponkan dry matters of leaf, fruit and flower. In 2019 and 2020, the yield of each organic fertilizer substitution treatment increased by 7.2% to 26.4% and 2.0% to 36.9%, respectively. (2) The soluble solids treated by organic fertilizer substitution treatment increased significantly by 7.4% to 9.8% compared with FP in 2020. Among other quality, T2 and T3 were better on the whole. (3) Each organic fertilizer substitution treatment of soil physicochemical properties promoted compared under FP in 2019 and 2020. The soil pH and organic matter treated by organic fertilizer will be significantly increased by 4.6% to 12.6% and 16.4% to 25.1%, respectively. (4) Compared with FP, each organic fertilizer substitution treatment of soil carbon flux was higher by 20.1%, while which of nitrous nitrogen was lower by 13.9%. With the increase of organic substitution ratio, the migration of nitrous nitrogen to deep soil was lower. (5) Through the analysis of the principal component and the comprehensive score of research index on ponkan’s growth, yield and quality, physicochemical properties of soil and environment, the score was sorted as T3>T2>T4>T1>FP>CK.【Conclusion】T3 (organic fertilizer replacement 20% of N, 51% of P, 36% of K) was the best under this research, and this treatment was not only beneficial to the growth and development of citrus trees, but also conducive to the formation of good physical, chemical characteristics of the soil and fruit high-quality yield, to a certain extent, to reduce the risk of greenhouse gas emission and soil nitrogen leaching. Table and Figures | Reference | Related Articles | Metrics

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Yield of Wheat and Maize and Utilization Efficiency of Nitrogen, Phosphorus and Potassium in Xinjiang TANG MingYao,SHEN ChongYang,CHEN ShuHuang,TANG GuangMu,LI QingJun,YAN CuiXia,GENG QingLong,FU GuoHai Scientia Agricultura Sinica    2022, 55 (14): 2762-2774.   DOI: 10.3864/j.issn.0578-1752.2022.14.007 Abstract （556）   HTML （53）    PDF （1189KB）（198）       Knowledge map    Save 【Objective】The objectives of the present paper were to understand current status of fertilizer utilization efficiency of wheat and maize in Xinjiang, to optimize their nutrient management, and to improve fertilizer utilization efficiency, so as to provide basic data and technique support for the food security of Xinjiang and as well as all the country. 【Method】72 field trials (40 for wheat and 32 for maize) were carried out in main grain growing areas of Xinjiang from 2018 to 2020. Four different treatments of fertilizer application were designed, including nitrogen, phosphorus and potassium (NPK), no nitrogen (PK), no phosphorus (NK), and no potassium (NP). Each experiment was conducted in triplicate. Then, the nutrient uptake of main grain crops, the response of nitrogen, phosphorus, and potassium fertilizers, the agronomic efficiency, the utilization rate and other parameters were examined under the current conditions of fertilization for agricultural production in Xinjiang. 【Result】(1) The average application amounts of N, P and K fertilizers for wheat in Xinjiang were 233.1 kg N·hm-2, 128.0 kg P2O5·hm-2 and 75.5 kg K2O·hm-2, respectively; the average application amounts of N, P and K fertilizers for maize were 254.9 kg N·hm-2, 148.0 kg P2O5·hm-2 and 67.8 kg K2O·hm-2, respectively. (2) The wheat yield of per unit area was 7 505 kg·hm-2 under NPK treatment, and the yield responses of N, P and K fertilizers were 2 206 kg·hm-2 (500-3 795 kg·hm-2), 2016 kg·hm-2 (288-4 230 kg·hm-2), and 1 362 kg·hm-2 (105-2 910 kg·hm-2), respectively. The average rates of yield increase for N, P and K fertilizers were 45.0%, 39.7% and 23.0%, respectively. The yield per unit area of maize under NPK treatment was 13 715 kg·hm-2, and the yield responses of N, P and K fertilizers were 4 657 kg·hm-2 (1 559-6 900 kg·hm-2), 1 942 kg·hm-2 (473-4 699 kg·hm-2), and 1 297 kg·hm-2 (113-5 440 kg·hm-2), respectively. The average rates of yield increase for N, P and K fertilizers were 52.2%, 21.2%, and 15.5%, respectively. (3) The uptakes of N and K by wheat and maize were relatively large, whereas the uptake of phosphorus was relatively small. The application of chemical fertilizers could significantly promote the uptake of nitrogen, phosphorus and potassium by plants, and increase the accumulation of nitrogen, phosphorus and potassium in soil. For NPK treatment, it required 2.7 kg (1.7-4.0 kg) of nitrogen (N), 0.8 kg (0.4-1.3 kg) of phosphorus (P2O5), and 2.1 kg (1.2-3.9 kg) of potassium (K2O) to form 100 kg of grains for wheat; for maize using the NPK treatment, it required 2.1 kg (1.5-2.9 kg) of nitrogen (N), 0.8 kg (0.4-1.2 kg) phosphorus (P2O5), and 2.1 kg (0.7-3.4 kg) of potassium (K2O) to form 100 kg of grains. (4) The agronomic efficiency of nitrogen fertilizer for maize was higher than that of wheat. There were no significant differences in the agronomic efficiencies of phosphorus and potassium fertilizers. The agronomic efficiencies of N, P and K fertilizers for wheat were 9.6, 15.9 and 18.7 kg·kg-1, respectively. Therefore, the agronomic efficiencies of P and K fertilizers were significantly higher than that of nitrogen fertilizer. The agronomic efficiencies of nitrogen, phosphorus, and potassium fertilizers for maize were 18.7, 13.4 and 18.1 kg·kg-1, respectively, N and K fertilizers were significantly higher than P fertilizer. (5) The utilization rates of N, P and K fertilizers for wheat were 41.4%, 21.8% and 45.2%, respectively. The utilization rates of N, P and K fertilizers for maize were 46.9%, 20.5% and 49.6%, respectively. The N and K utilization efficiency for wheat and maize were significantly higher than that of P. 【Conclusion】To date, the yield of wheat and maize in Xinjiang was high, the utilization efficiency of nitrogen, phosphorus and potassium was at a high level, and the utilization efficiency of nitrogen and potassium was significantly higher than that of phosphorus. In Xinjiang, wheat and maize yield was most sensitive to nitrogen deficiency. The phosphorus deficiency had lower influence on the wheat and maize yield, and the potassium deficiency had the lowest reduction. The amount of nitrogen application applied to wheat and maize in Xinjiang was reasonable. In contrast, the amount of potassium application was seriously insufficient. The excessive application of phosphate in wheat existed. In the future, it was necessary to increase the input of potassium fertilizer for wheat and maize and to reduce the input of phosphorus fertilizer for wheat. Table and Figures | Reference | Related Articles | Metrics

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Effects of Feedstock, Pyrolyzing Temperature and Biochar Components on the Growth of Chinese Cabbage ZHONG JiaLin,XU ZiYan,ZHANG YiYun,LI Jie,LIU XiaoYu,LI LianQing,PAN GenXing Scientia Agricultura Sinica    2022, 55 (14): 2775-2785.   DOI: 10.3864/j.issn.0578-1752.2022.14.008 Abstract （197）   HTML （34）    PDF （516KB）（83）       Knowledge map    Save 【Objective】 The objectives of this study were to investigate the effects of biochar feedstocks, pyrolyzing temperatures and biochar components on plant growth and to uncover the mechanism that how biochar increased crop yields. 【Method】 Six biochars were made from sawdust and maize stalk at pyrolyzing temperature of 350, 450, and 550℃. Each biochar was then separated into two parts through hot water extraction method, including the water soluble biochar extract and the washed biochar residue. A pot trial was conducted to investigate the effects of untreated biochar (BC), biochar extract (BE) and washed biochar residue (WB) application on the growth of non-heading Chinese cabbage (Brassica campestris ssp. chinesis). 【Result】 The aboveground biomass of Chinese cabbage under the addition of maize stalk biochars and their components was 16.1 g/pot on average, which was significantly higher than the values under sawdust biochars and their components (13.0 g/pot) amendment and the control (13.5 g/pot). Similarly, the root morphology index of root length, surface area, root volume and number of root tips under the addition of maize stalk biochars and their components improved greatly compared with sawdust biochar and the control. The aboveground biomass under the addition of washed biochar residues was 16.5 g/pot on average, which were 26.9% and 17.9% higher than the values under the addition of untreated biochar and the biochar extracts, respectively. The root length, surface area, root volume and number of root tips under washed biochar residues addition increased by 64.1%, 51.1%, 38.3% and 80.0%, respectively compared with biochar extracts addition. The biochars under different pyrolyzing temperature had no significant effect on the aboveground biomass and root growth of Chinese cabbage. Compared with the untreated biochar, the washed biochar residue addition increased the concentration of nitrogen (N) in aboveground biomass by 25.9%, while the concentration of phosphorus (P) and potassium (K) decreased by 39.7% and 14.1%, respectively. Soil pH, the concentration of soil organic carbon, total N, available P and K under the addition of maize stalk biochar and their components increased by 0.1 unit, 20.3%, 19.1%, 29.1% and 189.2% respectively compared with wood biochar addition. Compared with the untreated biochar, the washed biochar residue addition decreased soil organic carbon, total N, available P and K by 14.6%, 6.6%, 41.3% and 55.1%, respectively, while soil pH increased by 0.13 unit. Soil organic carbon, total N and available P under the addition of biochar extracts decreased by 49.8%, 18.9% and 24.2%, respectively, while soil pH and available K content was not affect. Correlation analysis showed that the aboveground biomass was positively related to root length, surface area, root volume, the number of root tips and soil pH value; while it was negatively correlated to the P concentration in the aboveground of Chinese cabbage. 【Conclusion】The feedstock and biochar component were the two main factors that regulating the response of plant growth to biochar amendment. The biochar from maize stalk was more suitable for soil amendment compared with wood biochar in terms of crop yield increase, and more crop yield could be obtained when maize stalk biochar was amended after hot water extracting. The water-soluble components presented in biochar played a key role in crop yield increase via promoting root growth. The promotion effect was closely related to biochar feedstock, pyrolyzing temperature and the chemical composition in biochar extracts. Table and Figures | Reference | Related Articles | Metrics

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The Characteristics of Ammonia Volatilization of Humic Acid-Urea Complex Combined with Urea from Different Fertilized Soils JING JianYuan,YUAN Liang,ZHANG ShuiQin,LI YanTing,ZHAO BingQiang Scientia Agricultura Sinica    2022, 55 (14): 2786-2796.   DOI: 10.3864/j.issn.0578-1752.2022.14.009 Abstract （229）   HTML （39）    PDF （601KB）（83）       Knowledge map    Save 【Objective】 The application of humic acid enhanced urea (HAU) can effectively reduce ammonia volatilization, and the humic acid in HAU, named UHA, plays a great role in this process. However, due to the reaction between humic acid and urea, the effect of UHA combined with urea on soil ammonia volatilization may be different from that of conventional humic acid (HA). Therefore, the relevant research will help to further reveal the mechanism of HAU reducing ammonia volatilization from soil. 【Method】In this study, UHA was extracted by absolute ethanol from HAU. Through indoor constant temperature soil incubation, the effects of HA or UHA combined with urea on soil ammonia volatilization from long-term unfertilized soil or fertilized soil were studied. The dosage of HA or UHA was 0.5% and 5% of the amount of urea, code named 0.5HA+U, 5HA+U, 0.5UHA+U, and 5UHA+U, respectively. At the same time, the treatments with urea (U) and without humic acid and urea (CK) were conducted. Soil ammonia fluxes and volatilization, soil urea-N, nitrate, and ammonium content, and soil urease activity were measured simultaneously. 【Result】(1) The ammonia volatilization from long-term fertilized soil for nitrogen fertilization treatments was higher than that from long-term unfertilized soil, which might be related to the decrease of soil pH, the weakening of soil nitrification process and the accumulation of ammonium nitrogen from urea hydrolysis caused by long-term fertilization. (2) Both HA and UHA combined with urea could effectively reduce soil ammonia volatilization, compared with U treatment, but the extent of the reduction depended on whether the soil was fertilized for a long time and the amounts of HA or UHA: urea combined with HA could significantly reduce soil ammonia volatilization for long-term unfertilized soil (P<0.05), and the ammonia volatilization of 0.5HA+U and 5HA+U was 4.4% and 22.9% lower than that under U treatment, respectively. However, the soil ammonia volatilization decreased by only 4.1%-7.5% under the treatment of HA combined with urea, which was not significantly different from that under the treatment of U, when the soil was long-term fertilization. However, urea combined with 0.5%UHA could significantly reduce soil ammonia volatilization (P<0.05) for long-term unfertilized and fertilized soil by 26.5% and 12.9%, respectively. (3) Urea combined with HA or UHA could effectively inhibit urease activity and promote soil nitrification process, respectively, thereby reduced soil ammonia volatilization. 【Conclusion】In summary, compared with HA, UHA combined with urea showed better performance on inhibiting ammonia volatilization under soil incubation, and the effect was independent of whether the soil was fertilized for a long time. Table and Figures | Reference | Related Articles | Metrics

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Effects of Basal Nitrogen and Foliar Zinc Application at the Early Filling Stage on Zinc Enrichment and Protein Components Content in Wheat Grain WU TianQi,LI YaFei,SHI JiangLan,NING Peng,TIAN XiaoHong Scientia Agricultura Sinica    2022, 55 (10): 1971-1986.   DOI: 10.3864/j.issn.0578-1752.2022.10.008 Abstract （272）   HTML （35）    PDF （615KB）（144）       Knowledge map    Save 【Objective】 Foliar zinc (Zn) application is an effective agronomic biofortification strategy to realize Zn enrichment of wheat grains and to combat the human Zn malnutrition. The aim of this study was to investigate the effects of spraying Zn with different nitrogen (N) inputs on Zn enrichment and content of protein and protein components in wheat whole grain and flour.【Method】 Based on the long-term positioning experiment, the spraying experiment of Zn in wheat for two consecutive seasons was conducted during 2018-2020. A split plot design was used with soil N rates of 0 (N0), 120 (N120) and 240 ∙hm-2 (N240) as the main plot factor, and the foliar application of distilled water (Zn0) and 0.4% ZnSO4·7H2O (Zn1) as subplot. The indexes were analyzed for this study, including Zn content of various nutritional organs, Zn mobilization and distribution from leaf and other vegetative organs to grain, and protein and protein component content in grains and flour at the early filling stage and maturation stage. 【Result】Compared with N0, the grain yield under N120 and N240 treatments was significantly increased by 88%-114%, but there was no significant difference between N120 and N240. Regardless of the N inputs, the foliar Zn application could significantly increase the Zn concentration in grains and flour and the grain Zn content reached the biofortification standard. Among those treatments, the Zn concentration of wheat grains under N120 and N240 was increased by 0.95 and 1.12 times than that under N0, respectively. Compared with N0, the N inputs increased the translocation of N and Zn transferred from leaf and other vegetative organs to grain at early grain filling stage, but reduced the transfer ratio of N and Zn: N decreased from 60.2% to 48.6% and Zn decreased from 42.3% to 26.5%. A significant positive linear correlation was found between the amount of N and Zn mobilization and the content of N and Zn in grain at maturity, and the synergistic effect of N and Zn was more significant at Zn1. Compared with the early filling stage, the content of storage protein (gliadin and glutenin) in grains and flour at the mature stage increased significantly, accounting for about 80%-84% of the protein content. The content of gliadin and glutenin in grain and flour was increased by N application more than that of albumin and globulin, and the gluten was the largest. The content of protein and protein components in grain and flour were not affected by spraying Zn. However, in terms of Zn1, the increase of gluten content in grain and flour was higher than that under the condition of Zn0 with the increase of N dosage, which was 37.5% and 38.1%, respectively.【Conclusion】Foliar Zn application could achieve Zn-rich grains but did not affect the content of protein and protein components in grains and flour, indicating that there was sufficient protein pool for Zn storage in grains and flour. Therefore, a reasonable amount of soil N combined with foliar Zn application could increase the N, Zn content and nutritional quality of the grains by ensuring high and stable yield on potentially Zn-deficient calcareous soils. Table and Figures | Reference | Related Articles | Metrics

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Spatial-Temporal Variability of Soil Nutrients and Assessment of Soil Fertility in Erhai Lake Basin GUO YingXin,CHEN YongLiang,MIAO Qi,FAN ZhiYong,SUN JunWei,CUI ZhenLing,LI JunYing Scientia Agricultura Sinica    2022, 55 (10): 1987-1999.   DOI: 10.3864/j.issn.0578-1752.2022.10.009 Abstract （401）   HTML （44）    PDF （2666KB）（124）       Knowledge map    Save 【Objective】By studying the spatial-temporal variation characteristics of tobacco-planting soil nutrients in Erhai Lake Basin (ELB), the objective of grading evaluation and spatial visualization of tobacco-planting soil fertility in this region was achieved, so as to provide a scientific basis for the nutrient management, balanced fertilization, and the control of agricultural non-point source pollution of tobacco-planting areas in ELB.【Method】Based on the 964 tobacco-planting soil samples in ELB collected in 2011-2013, 2018 and 2020, this study explored the spatial-temporal variability of nutrients and regional distribution patterns by using Geostatistics, Geographic Information Systems (GIS) technology, and Fuzzy integrated fertility index method to quantify the soil fertility in tobacco-planting areas. 【Result】The average values of soil pH, soil organic matter (SOM), total nitrogen (TN), Olsen-P (AP) and available potassium (AK) of tobacco-planting soil in ELB were 7.3, 59.6 g·kg-1, 3.5 g·kg-1, 54.4 mg·kg-1, and 192.0 mg·kg-1, respectively, all of which belonging to moderate variation. Tobacco-planting soil was rich in SOM, TN, AP and AK, and the proportions of areas within the upper-middle level accounted for 85.2%, 93.8%, 94.5% and 78.8%, respectively, showing obvious variation at regional scale. The area of tobacco-planting soil fertility were graded to five levels (from high to low: I to V), which accounted for 8.4%, 25.0%, 40.3%, 23.3% and 3.0%, respectively. The pH of tobacco-planting soil was relatively alkaline in ELB, which was higher in the northern than in the southern; the highest concentrations of SOM and TN occurred in the northern and the western region; the areas with high AP concentration were distributed in patches in the northern, eastern and western region of Erhai Lake; the areas with high AK concentration were distributed in flakes in the northern and eastern of Erhai Lake. 【Conclusion】Collectively, the fertility of the tobacco-growing soil in ELB was in high level, and the high-quality soil areas above grade III were mainly distributed in the northern and eastern region. Meanwhile, the tobacco-planting soil in the northern and western Erhai Lake were rich in nitrogen and phosphorus, and there was a risk of agricultural non-point source pollution in the region. Table and Figures | Reference | Related Articles | Metrics

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Effects of Arbuscular Mycorrhizal Fungi on Soil N2O Emissions During Maize Growth Periods ZHANG XueLin,HE TangQing,ZHANG ChenXi,TIAN MingHui,LI XiaoLi,WU Mei,ZHOU YaNan,HAO XiaoFeng Scientia Agricultura Sinica    2022, 55 (10): 2000-2012.   DOI: 10.3864/j.issn.0578-1752.2022.10.010 Abstract （265）   HTML （26）    PDF （914KB）（125）       Knowledge map    Save 【Objective】 The aim of this study was to understand the mechanism of arbuscular mycorrhizal fungi (AMF) on soil nitrous oxide (N2O) emissions, so as to provide the theoretical basis for increasing maize yield, improving nitrogen (N) use efficiency and reducing greenhouse gas emissions. 【Method】 A 2-factorial greenhouse experiment was established during maize growth periods in 2016 and 2017. The factors were as follows: (1) N fertilizer rates (180 kg N·hm-2 (N1) and 360 kg N·hm-2 (N2)), and (2) three mycorrhizae treatments, including a control (M0, neither roots nor AMF could enter the hyphal chamber from the growth chamber), an AMF treatment (M1, only AMF can enter the hyphal chamber from the growth chamber), and a root treatment (M2, both roots and AMF can enter the hyphal chamber from the growth chamber). Maize grain yield, plant biomass and their N accumulation, and soil N2O flux were measured. Soil bacterial community structure and diversity at maize maturity stage was determined by using the high throughput sequencing technique on Hiseq 2500 PE250. 【Result】 Both N fertilizer rates and mycorrhizae treatments significantly affected maize yield, plant N accumulation and soil N2O flux. Compared with M0, maize yield under M1 and M2 under the conditions of N1 input increased by 38% and 82%, by 30% and 52% for aboveground N accumulation, respectively, and reduced by 26% and 65% for soil inorganic N, respectively. However, under the conditions of N2 input, the maize yield under M1 and M2 increased by 16% and 48%, by 9% and 33% for aboveground N accumulation, and reduced by 34% and 55% for soil inorganic N, respectively. Compared with the M0, the total N2O emission of M1 and M2 treatments reduced by 17% and 40% under the conditions of N1 input, and by 41% and 67% for the N2O emission intensity, respectively; while under the conditions of N2 input, the total N2O emission reduced by 26% and 45%, and by 28% and 57% for the N2O emission intensity, respectively. Nonmetric multidimensional scaling analysis showed that both N fertilizer rates and mycorrhizae treatments had significant effects on bacterial communities’ composition. Compared with N1, the relative abundance of Proteobacteria and Gemmatimonadetes under N2 treatment on phyla level reduced by 6% and 15%, increased by 32% for Actinobacteria, while on genera level, the Streptomyces increased by 27%, and reduced by 8% for Gemmatimonas. Compared with M0 under the conditions of N1 input, the relative abundance of Streptomyces under M1 and M2 increased by 64% and 205%, by 31% and 53% for Gemmatimonas; however, under the conditions of N2 input, the relative abundance of Streptomyces under M1 and M2 increased by 10% and 93%, respectively, the Gemmatimonas for M1 reduced by 2%, and increased by 56% for M2. Moreover, the relative abundance of soil Streptomyces and Gemmatimonas was negatively related with soil N2O emission, but positively related with maize yield. 【Conclusion】 Arbuscular mycorrhizal fungi could reduce soil N2O emission under both higher and lower N fertilizer application rate by increasing the maize N uptake, and regulating the bacterial composition, especially increasing the relative abundance of Streptomyces and Gemmatimonas. Table and Figures | Reference | Related Articles | Metrics

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Effects of the Mixted-cropping of Chinese Milk Vetch and Rape on Soil Nitrous Oxide Emission and Abundance of Related Functional Genes in Paddy Fields YANG BinJuan,LI Ping,HU QiLiang,HUANG GuoQin Scientia Agricultura Sinica    2022, 55 (4): 743-754.   DOI: 10.3864/j.issn.0578-1752.2022.04.010 Abstract （324）   HTML （37）    PDF （571KB）（142）       Knowledge map    Save 【Objective】The aim of this study was to determine how a green manure mixted-cropping affected nitrous oxide (N2O) emissions from soil and the abundance of related functional genes in paddy field soil. The ultimate aim of this research was to identify a green manure mixted-cropping that had high and stable yields and reduces emissions, and was suitable for cultivation in the double-rice areas of southern China. 【Method】The effects of mixted-cropping of Chinese milk vetch and rape at different ratios (single Chinese milk vetch, single rape, 3/4 Chinese milk vetch +1/4 rape, 1/2 Chinese milk vetch +1/2 rape, and 1/4 Chinese milk vetch +3/4 rape) on N2O emissions and the abundance of related functional genes in paddy field soil were determined and compared. 【Result】(1) The crop species affected N2O emissions. The N2O emissions were similar among the different treatments. Among them the N2O emissions from winter crop soil were mainly concentrated at its flowering stage, and those during the rice growing period were concentrated at the tillering, filling, and maturity stages of early and late rice crops. On the whole, the N2O emissions from paddy fields were lower N2O in the early rice season than that in the late rice season. The overall N2O emissions flux in the paddy fields was higher in 2018 than that in 2019. (2) There was no significant difference in N2O cumulative emission of early rice under different treatments. The cumulative N2O emissions from a single seeding treatment were lower than those from mixed treatments over two consecutive years. The annual cumulative N2O emissions were lowest under CK1 in 2019. Among all the mixed treatments, the 3/4 Chinese milk vetch +1/4 rape treatment had the lowest annual cumulative N2O emissions. (3) In general, the copy number of amoA-AOA and amoA-AOB genes was higher in the soil of late rice than that in the soil of early rice, and the copy number of AmoA-AOA was up to two orders of magnitude higher in late rice soil than in early rice soil. The copy numbers of nirS, nirK and nosZ were higher in the soil of late rice crops than that in the soil of early rice crops, and the copy number of nirS was up to two orders of magnitude higher than those of nirK and nosZ in late rice soil. The mixted-cropping of Chinese milk vetch and rape increased the abundance amoA-AOA and amoA-AOB genes in soil, and amoA-AOA was the dominant functional gene. It also increased the abundance of nirS, nirK and nosZ genes in soil, and nirS gene was the dominant gene. The copy number of genes related to denitrification was one to three orders of magnitude higher than the copy number of genes related to nitrification, indicating that denitrification made a larger contribution to N2O emissions. 【Conclusion】Overall, the 3/4 Chinese milk vetch + 1/4 rape-early rice-late rice was the best mixed planting system, because it had the best combination of low N2O emissions as well as high yield and high fertility. Table and Figures | Reference | Related Articles | Metrics

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Effects of Single-Sided Application of Humic Acid on Maize Root Growth ZHOU LiPing,YUAN Liang,ZHAO BingQiang,LI YanTing Scientia Agricultura Sinica    2022, 55 (2): 339-349.   DOI: 10.3864/j.issn.0578-1752.2022.02.009 Abstract （389）   HTML （39）    PDF （686KB）（135）       Knowledge map    Save 【Objective】 Humic acid has complex structure and diverse functions. Studying the direct and indirect effects of humic acid on the growth of maize roots and revealing the regulation mechanism of humic acid on maize roots can provide the theoretical support for further research on the development and application of humic acid fertilizer synergists. 【Method】 A hydroponic experiment was carried out using Hoagland nutrition solution as the basic cultural liquid and maize cultivar of ‘Zheng Dan 958’ as material with a split-root design. The method of field plot split zone experiment was adopted and eight test treatments was set which was CK-control side (CK-C), CK-control side (CK-C) ), HA-non-applied side (HA-C), HA-applied side (HA-T), OHA3-non-applied side (OHA3-C), OHA3-applied side (OHA3-T), OHA6-non-applied side ( OHA6-C) and OHA6-applied side (OHA6-T) to study its effects on biomass, root vitality, root morphology and main chemical components of maize different organs. 【Result】 (1) Single-sided application of humic acid to separate roots significantly increased the fresh root weight of maize on the applied and unapplied sides. Compared with the control, the fresh root weight of maize with the applied side was increased by 21.9%-78.6%, which with the unapplied side was increased by 27.9%-49.3%. (2) The addition of humic acid significantly increased the maize root activity and the total TTC reduction of maize on the applied side and the non-applied side. Compared with the control, the maize root activity and total root TTC reduction of the OHA6-applied side increased the most, which increased by 76.9% and 216.9%, respectively. Compared with the control, HA-applied side and OHA3-applied side treatments increased the maize root activity by 59.8% and 35.1%, respectively. Compared with the control, OHA6-non-applied side, HA-non-applied side and OHA3-non-applied side treatments increased the maize root activity by 62.2%, 53.6% and 25.5%, respectively. (3) Adding humic acid treatment significantly increased the root volume, root surface area, average root diameter, root length and root number on the non-applied and applied sides of maize. (4) Single root application of humic acid could effectively increase the content of maize root ester compounds, protein, amino acids, nucleic acid cellulose and polysaccharides. The application side of humic acid treatment was more conducive to maize root carbohydrates than the non-application side. However, the untreated side under humic acid treatment was more conducive to the accumulation of maize root nucleic acid. The carbohydrate content of the aboveground parts of maize treated with humic acid was significantly higher than that under the blank treatment. 【Conclusion】 Regardless of whether it was HA or OHA3 and OHA6, when humic acid was applied to separate roots on one side, the growth and activity of maize roots on the side where humic acid was applied were significantly higher than those on the side without humic acid, indicating that humic acid had a direct effect on root regulation. The root growth of the whole plant treated with humic acid on one side was better than that under the control treatment without humic acid on both sides, indicating that humic acid also had an indirect effect in regulating root growth. The root growth of the whole plant treated with humic acid on one side was better than that under the control treatment without humic acid on both sides, indicating that humic acid also had an indirect effect in regulating root growth. Table and Figures | Reference | Related Articles | Metrics

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The Single Season Wheat Straw Returning to Promote the Synergistic Improvement of Carbon Efficiency and Economic Benefit in Wheat- Maize Double Cropping System WANG Liang,LIU YuanYuan,QIAN Xin,ZHANG Hui,DAI HongCui,LIU KaiChang,GAO YingBo,FANG ZhiJun,LIU ShuTang,LI ZongXin Scientia Agricultura Sinica    2022, 55 (2): 350-364.   DOI: 10.3864/j.issn.0578-1752.2022.02.010 Abstract （561）   HTML （41）    PDF （572KB）（199）       Knowledge map    Save 【Objective】 The objective of this study was to optimize straw returning method in wheat-maize double cropping system and to realize the coordinated improvement of system carbon efficiency and economic benefits, so as to promote the sustainable production of wheat-maize double cropping system. 【Method】Based on the long-term field experiment with 8 years of straw returning, this study analyzed the effects of wheat-maize straw returning (D) and single season wheat straw returning (S) on crop straw production and farmland carbon input, and identified the effects of different carbon inputs on wheat, maize, and annual yields, as well as yield stability and sustainability. The response characteristics of carbon efficiency and economic benefits to different carbon inputs in wheat-maize planting system were systematically analyzed. 【Result】 (1)The average annual straw returning quantity of D and S was 13.54 and 5.43 t·hm-2, respectively. The biomass of roots and stubble putting into farmland soil under D were about 3.04 and 2.14 t·hm-2, respectively, with no significant difference compared with S (P>0.05). The carbon input of root, root stubble and root exudates under S was 1.34, 0.97 and 1.35 t·hm-2, respectively, which showed no significant difference compared with D (P>0.05). (2) The input of agricultural resources and management carbon under S was 1.73 t C·hm-2, which was 51.29 kg C·hm-2 less than that under D. The total carbon input under S and D were 9.00 and 12.30 t C·hm-2, respectively, with a significant decrease of 26.82% (P<0.05). The difference of straw input was the main factor that caused the significant difference of farmland carbon input. The annual average straw carbon input under S was 2.31t C·hm-2, which was 60.85% less than that under D. (3) The annual average maize yield under S was 7.29 t·hm-2, which was 5.48% lower than that under D. The wheat yield under D (7.76 t·hm-2) was 5.67% and 0.26% lower than that under S, respectively. However, the sum of wheat and maize yields under S was not significantly different from that under D. The annual yield stability and sustainability indexes under S were 0.19 and 0.63, respectively, which showed no significant difference compared with D (P>0.05). (4) The annual grain carbon production of S and D were 6.27 and 6.25 t C·hm-2, respectively, and the plant carbon production were 15.96 and 15.74 t C·hm-2, respectively. The carbon production efficiency and carbon ecological efficiency under S were 0.69 kg·kg-1 and 1.77 kg·kg-1, respectively, significantly increased by 60.47% and 39.37% compared with D (P<0.05). (5) In wheat season, the inter-annual average output value and inter-annual average net income under S were ¥18 900 and ¥7 200 per hectare, respectively, which showed no significant difference compared with D (P>0.05). In the maize season, the annual average output value and the annual average net income of S were ¥19 100 and ¥8 010 per hectare, respectively, which were increased by ¥3 880 and ¥3 990 compared with D, respectively. The annual interannual average output value and interannual average net income under S were ¥38 600 and ¥15 600 per hectare, with 14.81% and 51.54% higher than those under D, respectively. 【Conclusion】Under the premise of not significantly affecting the annual wheat - maize grain yield, stability and sustainability of crop production, the only wheat straw returning reduced the maize straw returning, and synergistic improved the carbon efficiency and economic benefit of wheat-maize double cropping system. Table and Figures | Reference | Related Articles | Metrics

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Variation of Available Phosphorus in Purple Soil and Its Effects on Crop Yield of Rice-Wheat Rotation Under Long-Term Fertilizations REN JiaXin,LIU Jing,CHEN XuanJing,ZHANG YueQiang,ZHANG Yong,WANG Jie,SHI XiaoJun Scientia Agricultura Sinica    2021, 54 (21): 4601-4610.   DOI: 10.3864/j.issn.0578-1752.2021.21.010 Abstract （362）   HTML （40）    PDF （522KB）（276）       Knowledge map    Save 【Objective】Based on the analyses of soil Olsen-P variation in the purple soil and its effects on crop yield under long-term different fertilizations in the rice-wheat rotation, this paper provided a theoretical basis for efficient and rational P management in purple soil. 【Method】This study were conducted based on the 27-year rice-wheat rotation trial platform in the Purple Soil Fertility Monitoring Station of the national soil fertility monitoring network. The soil Olsen-P content and crop yields of 10 different fertilization treatments were measured and compared, including CK treatment (crops growing without fertilization), N, NP, NK, PK, NPK (treatments with different chemical nitrogen (N), phosphorus (P), potassium (K) fertilizations), and M, NPKS, NPKM, 1.5NPK+M (chemical fertilizer combined with organic manure (M) and straw return (S) treatments) from 1991 to 2018. Then, the plant P uptake per 100 kg grains yield and the recovery rate of P by different fertilizations were calculated and compared, respectively. The responses between soil Olsen-P increment and cumulative P depletion were explored. In addition, the response curve of crop yield to soil Olsen-P content in the purple soil was figured by different modelling methods. The agronomic critical value of Olsen-P content in purple soil was finally calculated. 【Result】Long-term application of P fertilizer could significantly increase soil Olsen-P content. The average annual increment of soil Olsen-P content was 0.80-2.32 mg·kg-1 in P application treatments, whereas the soil Olsen-P content of CK, N, NK and M treatments decreased year by year to a steady state. The cumulative P surpluses by the 27-year P application treatments were 244.8-698.2 kg P·hm-2, among which the cumulative P surplus of the 1.5NPK+M treatment was the highest. A significant linear correlation between cumulative soil P surplus and soil Olsen-P increment could be found in P application treatments. In detail, soil Olsen-P increased by 4.27-6.5 mg·kg-1with 100 kg·P·hm-2 cumulative surplus in P application treatments. Fertilization could significantly increase crop yields and P uptake in the long-term rice-wheat rotation system. The plant P uptake per 100 kg rice yield was 0.17-0.41 kg, whereas the plant P uptake per 100 kg wheat yield was 0.25-0.57 kg. The utilization rates of P under all treatments were 10.3%-39.7%. Four models (linear-platform model, linear-linear model, BoxLucas model, and Michelice model) were good for fitting the response of crop yield to Olsen-P content in purple soil. The agronomic critical value of Olsen-P content in purple soil of rice and wheat calculated by linear-linear model (with the highest R 2) were 13.28 mg·kg-1 and 9.93 mg·kg-1, respectively. 【Conclusion】Appropriate application of P fertilizer could significantly improve the P uptake of crop in rice-wheat rotation system on purple soil, crop yields and soil available P content. The linear-linear model was recommended to calculate the critical value of Olsen-P content in purple soil under rice-wheat rotation system. Application rates of P fertilizer should be adjusted timely according to the difference between actual soil Olsen-P content and agronomic critical value of Olsen-P content in productivity. Table and Figures | Reference | Related Articles | Metrics

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Mineralization Characteristics of Soil Organic Carbon and Its Temperature Sensitivity in Wheat Field Under Film Mulching CAO HanBing,XIE JunYu,LIU Fei,GAO JianYong,WANG ChuHan,WANG RenJie,XIE YingHe,LI TingLiang Scientia Agricultura Sinica    2021, 54 (21): 4611-4622.   DOI: 10.3864/j.issn.0578-1752.2021.21.011 Abstract （318）   HTML （37）    PDF （1152KB）（218）       Knowledge map    Save 【Objective】Clarify the response of dryland soil organic carbon (SOC) mineralization to long-term film mulching and its temperature sensitivity, and further understand the transformation and stabilization mechanism of SOC, providing theoretical support for dryland soil fertility and crop productivity. 【Method】Based on the dryland wheat field mulching experiment that began in 2012 in the southeastern of the Loess Plateau, soil samples of 0-20 cm layer for different mulching cultivation modes (farmer’s practice fertilization (no film mulching), monitoring fertilization (no film mulching), monitoring fertilization plus ridge mulching-furrow planting (mulching), and monitoring fertilization plus whole field film (mulching)) were collected, and then the soil samples were incubated at different temperatures (15, 25 and 35℃). The lye absorption method was used to determine the SOC mineralization rate at the 1st, 3rd, 5th, 7th, 14th, 21st, 28th, 35th and 42th days after incubation, combined with two component model to fit the cumulative mineralization and decomposition rate of soil active and recalcitrant organic carbon pool, investigate the effect of film mulching on SOC mineralization characteristics and the response of SOC mineralization to temperature.【Result】The results showed that the increasing temperature had significantly increased SOC mineralization rate, cumulative mineralization and the mineralization amount of recalcitrant organic carbon pool (Cs), but markedly decreased the temperature sensitivity (Q10) and activation energy (Ea). The mineralization rate and cumulative mineralization of SOC at 25℃ and 35℃ were about twice that at 15℃, and the mineralization of Cs increased by 93.4% and 105.3% respectively compared with that at 15℃. But Q10 (25-35℃) is 19.3% lower than Q10 (15-25℃), and Ea (25-35℃) is 68.0% lower than Ea (15-25℃). Plastic film mulching significantly increased the SOC cumulative mineralization, the mineralization of Q10, Ea and Cs. Compared with farmer fertilization treatment, both monitoring fertilization plus ridge mulching-furrow planting and monitoring fertilization plus whole field film treatments had significantly increased the SOC cumulative mineralization by 26.5%-38.6% (25℃) and 27.8%-64.4% (35℃), respectively, while monitoring fertilization plus whole field film treatment had the largest improvement. The monitoring fertilization plus whole field film treatment had also significantly increased Q10 by 28.5% (15-25℃) and 25.8% (25-35℃) and Ea by 93.4% and 193.1%, respectively. Furthermore, monitoring fertilization plus whole field film treatment had markedly increased the mineralization amount of Cs by 115.8%-2 208.2%. 【Conclusion】Therefore, film mulching accelerated the SOC mineralization in the dryland wheat field of the Loess Plateau, especially for monitoring fertilization plus whole filed filming treatment mainly increased the mineralization of recalcitrant organic carbon pool, and then significantly increased the cumulative mineralization of SOC and its temperature sensitivity. Table and Figures | Reference | Related Articles | Metrics

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