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01 February 2018, Volume 51 Issue 3

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Nutrient Management in Soil-Crop-Animal Production System

Guidance of the SPECIAL ISSUE: Nutrient Management in Soil-Crop-Animal Production System

MA Lin, MA WenQi, ZHANG FuSuo

Scientia Agricultura Sinica. 2018, 51(3):  401-405.  doi:10.3864/j.issn.0578-1752.2018.03.001

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Significance and Research Priority of Nutrient Management in Soil-Crop-Animal Production System in China

MA Lin, BAI ZhaoHai, WANG Xuan, CAO YuBo, MA WenQi, ZHANG FuSuo

Scientia Agricultura Sinica. 2018, 51(3):  406-416.  doi:10.3864/j.issn.0578-1752.2018.03.002

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With a rapid development and decoupling between crop and animal production, China already faces serious groundwater pollution by nitrate leaching, eutrophication of surface waters, as well as air quality degradation caused by over-fertilization and manure discharge. It is important to (1) quantify nutrient flows in “soil-crop-livestock” production system, (2) optimize nutrient flows and recycling by coupling crop and livestock systems, and (3) mitigate nutrient losses and improve nutrient use efficiency. These studies provide a scientific basis for national action (e.g. reduction of chemical fertilizer application, replacement of chemical fertilizer by manure, resource utilization of livestock waste and mitigation of non-point source pollutions). The objectives of this study are to review the published studies on nutrient management in crop and animal production, analyze the characters of nutrient inputs, use efficiencies and losses of crop and animal production in China in the past decades, and to prospect research priority of nutrient management in soil-crop-animal production systems in China. For increasing productivities of grain, overuse of chemical fertilizer is common, lack of manure recycling. The biggest challenge facing China today is de-coupling crop and animal production. The nutrient use efficiency of crop and animal production decreased and nutrient losses increased dramatically in the past decades in China. The highest emissions are estimated in or around big metropolitans. Coupling crop and animal production is the main solution of sustainable intensive agriculture. According to the international research experiences, research should focus on improving manure management, mitigation of nutrient losses and increasing nutrients recycling rate of agricultural wastes. The integrated nutrient management of the soil-crop-animal production systems has become the focus of global concern. Key research topics of nutrient management in crop and animal production include (1) quantifying nutrient flows and environmental impacts of ‘soil-crop-animal’ production systems, (2) strategies of chemical fertilizer replacement by manure, (3) mitigation options of manure management from ‘feeding-housing-storage-treatment-application’ chain, and (4) farming system design for achieving high productivities and nutrient use efficiencies in crop and animal production.

Characteristics of Nitrogen and Phosphorus Nutrient Flow in Farming and Animal Husbandry System in Northeast China

ZHANG XiaoMeng, WANG Yin, YAN Li, FENG GuoZhong, GAO Qiang

Scientia Agricultura Sinica. 2018, 51(3):  417-429.  doi:10.3864/j.issn.0578-1752.2018.03.003

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【Objective】Northeast China is an important commodity grain base and the place of animal husbandry production in China. The mass production of farming and animal husbandry products influences the trend of nutrient flow, and the nutrient flow in different areas exists some differences. To make clear the characteristics of nutrient flow in different areas, and to reveal their problems, the reasonable and optimal strategy for different flow characteristics was put forward, which will provide a theoretical basis for nitrogen and phosphorus nutrient management in regional farming and animal husbandry system.【Method】With statistical data and literatures collection from 1984 to 2014 taking the farming and animal husbandry system in the three provinces of Northeast China as the research object by NUFER model (nutrient flows in food chain, environment and resources use). The flow and loss of nitrogen and phosphorus in the farming and animal husbandry system in each province were estimated. And the comprehensive evaluation of nitrogen and phosphorus nutrient utilization, loss path and utilization efficiency in each province was made. the trends and characteristics of nitrogen and phosphorus flow in thefarming and animal husbandry system were studied.【Result】In 1984, the total nitrogen input of the farming and animal husbandry in Jilin, Liaoning, Heilongjiang area was 669, 746 and 716 Gg, respectively. the total phosphorus input of them was 121, 222 and 169 Gg, respectively. In 2014, the total nitrogen input increased to 1 899, 1 572 and 2 256 Gg; and the phosphorus input reached 471, 393 and 769 Gg in the areas, respectively. The input amounts of nitrogen and phosphorus nutrients were as follows: Heilongjiang＞Jilin＞Liaoning. The loss rates of nitrogen nutrition in Jilin area and phosphorus nutrition in Liaoning area were the highest. The recycling rate of nitrogen and phosphorus was the highest in Jilin, and the lowest in Liaoning. In the past 30 years, the nitrogen use efficiency of farm system in Jilin, Liaoning and Heilongjiang decreased by 10%, 11%, and 32%, respectively. The use efficiency of phosphorus decreased by 16%, 2% and 23%, respectively. In the livestock and poultry production system, the utilization of nitrogen nutrient increased by 3%, 11% and 10%, respectively; and the utilization of phosphorus content increased by 0.8%, 1.9% and 3.2%, respectively. Nitrogen use efficiency in farming and animal husbandry system decreased from 26%, 36%, 52% in 1984 to 13%, 21%, 22% in 2014, respectively. The overall trend was Heilongjiang＞Liaoning＞Jilin; phosphorus use efficiency decreased from 25%, 25%, 31% in 1984 to 9%, 14%, 10% in 2014, respectively. The trend was as following: Liaoning＞Heilongjiang＞Jilin.【Conclusion】The input of nitrogen and phosphorus in farming and animal husbandry system in Northeast China increased significantly from 1984 to 2014. There were obvious differences among different areas. The total available nitrogen and phosphorus nutrients were the highest in Heilongjiang, while the recycling efficiency of nitrogen and phosphorus was the highest in Jilin. In Northeast China, the efficiency of nitrogen use in Heilongjiang was higher than that in other areas, and the efficiency of phosphorus use in Liaoning was higher than that in Jilin and Heilongjiang. The loss rates of nitrogen and phosphorus in Jilin and Liaoning were higher than those in other areas. Therefore, it is necessary to make reasonable suggestions for the management of farming and animal husbandry according to the characteristics of nutrient flow in different regions, so as to provide a basis for the sustainable development of farming and animal husbandry in Northeast China.

Nutrient Flow and Environmental Effects of “Soil-Feed-Livestock” System in Metropolis: A Case Study in Beijing

WEI Sha, BAI ZhaoHai, WU DiMei, XIA LiJiang, JIANG RongFeng, MA Lin

Scientia Agricultura Sinica. 2018, 51(3):  430-441.  doi:10.3864/j.issn.0578-1752.2018.03.004

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【Objective】With the accelerated process of urbanization and the rapid development of economy, people’s demand for food and diet has changed greatly, especially the demand for livestock products increased significantly. The intensive development of crop-livestock production in the suburbs meets the increasing demand for animal products and high-quality plant products, but it also brings serious waste of resources and environmental pollution. The objective of this study is to analyze the nutrient flow and environmental emission characteristics of peri-urban area and provide scientific suggestions for the integrated management of nutrient resources, promoting the combination of agriculture and animal husbandry and protecting the ecological environment.【Method】 In this study, the survey data about the farm management, feed sources and inputs, manure management and land use of a total of 200 farms in Beijing (92 pig farms, 28 dairy farms, 11 beef cattle farms, 27 layer farms, 26 broiler farms and 16 duck farms) were used to summarize the characteristics of different scales of farming system Beijing. The performance of nitrogen and phosphorus flow characteristic, use efficiency and environmental loss of “soil-feed-livestock” production system in Beijing from 1980 to 2013 was assessed, using data of farm survey, historical statistics data and literature and nutrient flows in food chains, environment and resources model (NUFER) and calculations with the NUFER model. The spatial and temporal variations of nutrient flow characteristics, use efficiency and environmental emission characteristics of farming and animal system in 1980 and 2013 were compared. 【Result】 The result of characteristic of nitrogen and phosphorus flow showed that the ratio of the input and output of nitrogen and phosphorus in the system had a great change. The main nutrient input was main feed import from other place in 2013, while the main inputs for nitrogen and phosphorus were from by-products feed import in 1980. The nitrogen and phosphorus loss was the main output in 2013, while the manure land use was the main output in 1980. The reason for the change is that with the development of urbanization and intensive farming system, more and more nutrients are concentrated in the urban area, resulting in a greater proportion of environmental loss. Nitrogen use efficiency of “soil-feed crop-livestock” production system in 2013 was 29.0% which was similar with 1980. Among them, NUE_C of crop system in 2013 was 33.0%, lower than that in 1980 (39.5%), while NUE_A of animal system in 2013 was 20.6%, higher than that of 1980 (17.8%). Nitrogen and phosphorus loss of per hectare and the ways of loss have great changes. In 2013, loss of nitrogen and phosphorus per hectare of arable land was 436.5 and 37.5 kg·hm^-2, respectively, while the nitrogen and phosphorus loss in 1980 was 77.5 and 3.2 kg·hm^-2, respectively. In 2013, the loss of nitrogen and phosphorus in cultivated land increased 4.6 and 10.7 times as compares with 1980, respectively. In 2013, nitrogen loss from gas emission accounted for 61.1% of the total nitrogen loss, followed by direct discharge (31.3%) and leaching and runoff (7.6%). Compared with 1980, the proportion of gas loss decreased significantly, while the proportion of discharge losses increased significantly which exceeding leaching runoff became the second largest loss. In 2013, the ratio of direct phosphorus emissions exceeded that of leaching runoff to become the largest proportion of emission. Meanwhile, the loss of nitrogen and phosphorus in “soil-feed-animal” system in Beijing increased rapidly in the suburbs and decreased rapidly in the urban center. 【Conclusion】 During 1980-2013, the characteristics of nitrogen and phosphorus flow in “soil-feed-animal” system changed greatly. These changes are closely related to the changes in planting and breeding structure, the scale of animal farming, and environmental protection policies.

Nitrogen Flow and Environmental Effects of Crop-Livestock System in Typical Area of North China Plain-A Case Study in Hebei Province

TONG BingXin, ZHANG HuaFang, GAO XiaoXian, HOU Yong, MA WenQi

Scientia Agricultura Sinica. 2018, 51(3):  442-455.  doi:10.3864/j.issn.0578-1752.2018.03.005

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【Objective】The objective of this study is to evaluate the characteristics of nitrogen (N) flow and environmental effects in crop-livestock system in Hebei Province, North China Plain at regional level for the period of 1980-2015, analyze the nitrogen cycle use and recycling efficiency and the degree of combination of agriculture and animal husbandry, discuss the improved management strategies of nitrogen, and to provide a basis for the sustainable development of crop-livestock system in China. 【Method】Taking the crop-livestock system in Hebei province as the research boundary, based on the material flow analysis (MFA) method, the input-output balance, recycling and loss of N in the crop system, livestock system and crop-livestock system of Hebei Province were analyzed from the year 1980 to 2015, supplemented with the data from national and regional statistics, literature and farmers’ surveys. N use efficiency, surplus and recycling ratio were considered as the indexes to analyze N flow characteristics and environmental effects. The N input items of crop-livestock system mainly included chemical fertilizer, biological nitrogen fixation, deposition, irrigation, human feces and urine reused as fertilizer and imported feed; the N output items mainly included the locally consumed and exported main product and by-product of crop and livestock systems, N lost to water body and air; the internal N recycling items mainly included by-product of crop system returned to field, main product and by-product of crop system as local animal feed, and livestock manure returned to field. 【Result】In the crop system, the total N input and the amount of N in harvested crops increased by 1.9 and 1.5 times from 1980 to 2015. The N surplus and loss from crop system increased by 1.7 and 1.9 times, respectively, leading to the decrease in N use efficiency (from 47.2% to 41.4%). Compared with the organic fertilizer N input, the chemical N fertilizer input accounted for more than 60% of the total N input in farmland, and in recent years it was close to 70%. The N balance of farmland varied greatly among regions. In terms of N input, Handan and Tangshang were higher (＞600 kg·hm^-2), and Chengde was the lowest (＜200 kg·hm^-2). In terms of N surplus, Tangshang was the highest (267.8 kg·hm^-2), while Hengshui was the lowest (51.6 kg·hm^-2). The amount of N input in livestock system also increased significantly, reaching a maximum on 2005, which was 7.7 times higher than that in 1980. The amount of N in animal products and animal excretion increased rapidly. Especially the N production of feces and urine increased from 21.8×10⁴ t to 115.3×10⁴ t. The N produced by manure was the highest in Handan (377.3 kg·hm^-2), and Hengshui was the lowest production (122.6 kg·hm^-2). The N dependence rate of exogenous feed increased from 60.5% to 72.7%, the N return rate of livestock feces and urine decreased from 70.4% to 30.2%, but the N utilization efficiency of livestock system increased from 6.4% to 16.3%. In the crop-livestock system, the 36-year accumulated N input was as high as 9 038.9×10⁴ t. The chemical N fertilizer input accounted for about 55.7% of the total N input, and N input via imported feed occupied 33.1% of total N input. For the total accumulated N output, the N output via crop and animal products (2 537.4×10⁴ t), accounting for 28.1% of the total input N. The 36-year accumulated N loss into air and water was 4 061.2×10⁴ t, accounting for 44.9% of the total N input. 【Conclusion】 From 1980 to 2015, the amount of N input in crop-livestock system in Hebei Province increased significantly, N enrichment and environmental emissions were serious, N use efficiency was low, and there were great differences in N balance per unit area in different regions. The N cycle between crop production and livestock production is seriously disjointed. Therefore, we should make full use of local feed resources, improve the return rate of organic fertilizer, and take the road of combination of agriculture and animal husbandry, so as to reduce the cost of “high input and low efficiency” caused by “separation of agriculture and animal husbandry” and promote sustainable development of agriculture and animal husbandry.

Nutrient Flow and Environmental Effects on Crop-Livestock System in Farming-Pastoral Transition Zone - A Case Study in Shanxi Province

ZHANG JianJie, GUO CaiXia, LI LianFen, ZHANG Qiang

Scientia Agricultura Sinica. 2018, 51(3):  456-467.  doi:10.3864/j.issn.0578-1752.2018.03.006

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【Objective】The objective of this study is to explore the characteristics of nitrogen (N) flow of crop-livestock systems and its environmental effects on farming-pastoral transition zone in northwestern Shanxi Province, further to give scientific suggestions on the nutrient management and to speed up the adjustment progress of industrial structure in farming-pastoral transition zone in Shanxi Province.【Method】a systematic and quantitative analysis on the nutrient balance, nutrient losses of crop-livestock production in farming-pastoral transition zone (42 counties in total, mainly involving Datong, Shuozhou, Xinzhou, Lüliang, Linfen and Taiyuan) in Shanxi Province was reported using a coupled NUFER model (nutrient flows in food chains, environment and resources use) with GIS after collecting and sorting of data from statistical yearbooks data, literature, and field investigation.【Result】 In different counties, the N fertilizer application showed a great disparity, ranging from 6.7 to 253 kg·hm^-2, which means a 38 times difference between the maxima and the minima. The N input structure of different counties also varied, due to the different N application habits and cropping systems. Crop N uptake ranged from 19.11 to 96.75 kg·hm^-2, and the high amounts of crop N uptake were found in North and South regions, and low values in the middle regions. Crop N surplus ranged from -16 to 202 kg·hm^-2, showing a coexistence of N sufficient and N surplus. There was a great difference in external N input by feed in livestock production system in the zone. In Shanyin county of Shuozhou City, the external N input by feed reached up to 9 400 t, whereas in Wuzhai of Xinzhou City and Xixian, Daning and Puxian of Linfen City, the demand of feed by livestock production system was met by local cropping system. This shows a great variation in the livestock production scale and farming-pastoral industrial structure among those counties. N uptake of animal main product per unit area of farming land was 1.51-27.50 kg·hm^-2, with a range of 25.99 kg·hm^-2, indicating a great disparity in the livestock productivity level among different counties. In the northern counties of Shanyin, Huairen and Datong, N uptake of animal main products was ＞13 kg·hm^-2, showing a high N use efficiency of livestock production system in these counties. In the northern regions, the N load by manure was high (＞50 kg·hm^-2). There was an obvious spatial trend of N loss in crop-livestock production system. Grade I area (＞200 kg·hm^-2) was found in the north of the zone, Grade II area (120-200 kg·hm^-2) was found in the north and south of the zone, and Grade III area (＜120 kg·hm^-2) mainly distributed in the middle of the zone. Therefore, N loss and environmental issues occur in the crop-livestock production process in the northern part of the zone should be paid close attention in the future. 【Conclusion】 Unreasonable agricultural production structure and the segregation of agricultural and animal husbandry systems were the main reasons for the low N use efficiency in the farming-pastoral transition zone in northwestern Shanxi Province. In the future management of farmland nutrient resources, apart from rational spatial allocation of N resources, not only N input by both chemical fertilizers and livestock excrement/urine should be taken into account, but also N input from the environment. Also, the coupling of farmland production system and animal husbandry production system should be emphasized. By these means the production of crop and animal products at the minimum environmental costs can be achieved.

Nitrogen Flow of Crop-Livestock Production System and Its Driving Forces in Chongqing over the Past 20 Years

CHEN XuanJing, GONG YaHui, XIE Jun, ZHANG YueQiang, CHEN XinPing, SHI XiaoJun

Scientia Agricultura Sinica. 2018, 51(3):  468-480.  doi:10.3864/j.issn.0578-1752.2018.03.007

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【Objective】 The objectives of this study are to evaluate the characteristics of nitrogen (N) flow in the crop-livestock system and analyze the main pathways of N loss and main drivers of the change in N flow in the crop-livestock system, put forward the effective N management measures, and to provide a powerful technical support for efficient N resource adoption in crop-livestock system in Chongqing.【Method】The crop-livestock system of Chongqing was defined as research case. A quantitative analysis of the N flow and loss and of their relationships with human activities from 1996 to 2015 was reported using the nutrient flow in food chain, environment and resources use model (NUFER). The data were mainly derived from literature, statistics and research reports. Pathways to a sustainable N use were explored through scenario analysis of different N managements in 2020.【Result】The total N input of crop-livestock system in Chongqing increased by 19.2% from 1996 to 2015. The amount of N input reached 1 006 Gg in 2015 and fertilizer consumption contributed 57% to it. The total N output of crop-livestock system in Chongqing increased by 16.5% from 1996 to 2015 and it has reached 844 Gg in 2015. Environmental loss was the largest part of N output in the crop-livestock system, which accounted for 61.7% of total output. Crop and animal production systems contributed 45.1% and 54.9% to the total N loss in 2015, respectively. The total amount of N cycle in the crop-livestock system increased by 42.7% and reached 448 Gg in 2015. The N amounts in manure and straw returning reached 32.7 and 95.0 Gg, respectively, which increased by 55% and 44% from 1996 to 2015. The cultivation proportion of vegetable and fruit to total sown areas increased from 10% to 28% from 1996 to 2015. Meanwhile, the percentage of cereals crops area dropped from 82% to 62%. In addiction，the export of main animal products increased by 83%, such as meat, milk and eggs. A significant liner relationship was observed between changes in N use and loss and changes in production structure, while the relationship between changes in N use and loss and changes in gross domestic production (GDP) was non-linear. It suggested that the dominant factor affecting N flow should be production structure, and GDP just played a role in stimulating consumption of crop and animal products. If the goal of agricultural production in the “13th Five-Year Plan for Agricultural Development in Chongqing Municipality” is fulfilled by 2020 with current N fertilizer inputs and N management practices, it will increase N loss by 18 Gg and reduce N use efficiency by 1.2% relative to the status of 2015. Scenario with increased the N cycling rate in the crop-livestock system and optimized nutrients management of crop production, indicated 15% and 4.2% reductions in N fertilizer input and N loss, respectively. It also would greatly increase N use efficiencies (NUE).【Conclusion】The characteristics of N flow in the crop-livestock system have been greatly changed over the past 20 years in Chongqing. Increased N input and total environmental loss were observed since 1996. The main driver for these changes was adjustment of production structure. Key measures for ensuring food production and minimizing environmental costs are (1) reducing direct emission of N from the livestock system to the environment, (2) enhancing the recycling of straw and manure, (3) optimizing N management and improving NUE in crop production system.

Spatial-Temporal Distribution of Nitrogen Nutrient Flow and Environmental Effects of Crop-Livestock System in Yunnan Province

 

LI XiaoLin, ZHENG Yi

Scientia Agricultura Sinica. 2018, 51(3):  481-492.  doi:10.3864/j.issn.0578-1752.2018.03.008

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【Objective】The objective of this paper is to study the nitrogen (N) nutrient flow of crop-livestock system (CLS) and evaluate its related environmental effects in Yunnan province, increase the utilization efficiency of N, improve the agricultural eco-environment, and to provide a scientific basis for making the policies obeying the agricultural development law in Yunnan province. It is also of strategic importance to realize the sustainable development of social eco-economics.【Method】the temporal differentiation characteristics of N flow of CLS in terms of time series were analyzed based on the NUFER model (nutrient flows in food chains, environment and resources use). the spatial distribution of N flow of CLS in 16 prefectures of Yunnan province in 2014 were analyzed based on GIS from the perspective of spatial pattern.【Result】N inputs of CLS in Yunnan province increased year by year from 1995 (2.1×10⁶ tons) to 2014 (3.5×10⁶ tons). The applications of N fertilizer and the imports of feed primarily caused the increasing of N inputs to CLS. The N uptake amount of main products of farmland and that of animal production systems showed the same increasing trends along time, and the multiples of which were 2.1 and 8.5 times from 1995 to 2014, respectively. The N uptake amount increased a lot in 2000 and 2006, because of the expansion of the crop growing area and livestock breeding scale, and the improvement of the planting techniques and also the mode in the development of agricultural and animal husbandry of Yunnan. N flow of CLS in Yunnan province exhibited great imbalance, and the input of N presented a distribution characteristic showing high inputs in the center and the gradual decreasing trends towards the surrounding area. N uptake amount coordinated with the status of the regional social economic development. The more the developed region economy, the higher the N uptake amount. The significant reasons of N losses in CLS were the ammonia volatilization which attributed to the runoff, erosion and leaching caused by terrain condition and some unreasonable fertilization patterns. According to the characteristics of input, uptake and loss of N in Yunnan province, four types of N flow were divided as follows: high input with high discharge (Dali, Kunming and Honghe), high input with low discharge (Qujing, Lijiang, and Chuxiong, etc.), low input with high discharge (Diqing and Zhaotong, etc.) and low input with low discharge (Nujiang and Puer).【Conclusion】 Due to the traditional fertilization approaches which led to the excessive fertilization and the consequent great amount of N entering into the atmosphere through ammonia emission, and also due to the runoff and leaching effect of N from the urines and feces of livestock, the economic benefit of agricultural production was reduced and the environment was also contaminated. The N losses were higher in Dali, Kunming and Honghe based on the spatial distribution characteristics. Therefore, there are several aspects which should be amended like improving the pattern of fertilization, upgrading the utilization efficiency of fertilizer, improving the livestock breeding mode and also increasing the amount of urines and feces returning to the fields. Different CLS N optimized management techniques should be adopted according to the characterizes of different areas, and other approaches such as increasing manure nutrient cycling, improving the efficiency of N nutrient, decreasing fertilizers and exogenous feed requirements and reducing the discharge quantity into air and water should also be conducted in order to realize the reasonable cycling of nitrogen in the CLS.

Temporal and Spatial Changes of Nutrient Flows and Losses in the Peri-Urban Crop-Livestock System in Luancheng

MA YiFei, BAI ZhaoHai, MA Lin, NIE YongQiang, JIANG RongFeng

Scientia Agricultura Sinica. 2018, 51(3):  493-506.  doi:10.3864/j.issn.0578-1752.2018.03.009

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【Objective】 Crop-livestock production structure and their integration rate has been changed greatly in China since the reform and opening policy. These changes have large impacts on the nutrient flows and environmental losses in the crop-livestock production chain. Here, Luancheng district of Hebei province was used as an example to analyze the temporal and spatial changes of crop-livestock production structure and impacts on nutrient flows and losses from 1985 to 2014, and to determine the key impacting factor of nutrient losses in crop-livestock system. These results can be used to improve the understanding of sustainable agriculture not only for Luancheng district, but also for other counties which faced the same situation with Luancheng district. 【Method】 the nutrient flows in Luancheng district were analyzed by using NUFER (nutrient flow in the food system, environment and resource) model and field survey. The NUFER model calculated nitrogen (N) and phosphorus (P) flow, use efficiency and environmental losses of crop production system, livestock system, food processing system and household consumption system. Field surveys were conducted through the face-to-face questionnaires to collect information about the nutrient management. The contents of the questionnaires include the production practices and nutrient input-output of crop system, livestock feeding management and manure management practices, manure recycle to crop land and nutrient input-output of the livestock system. 【Result】 In 2014, the percentage of vegetable and fruit sown area to the total sown area was 25%, N and P inputs of agricultural land were 763 kg N·hm^-2 and 335 kg P·hm^-2, the average surplus of N and P were 132 kg N·hm^-2 and 237 kg P·hm^-2 agricultural land, the livestock density reached up to 18 LU/hm² agricultural land, feed import rate reached to 75%, input of external N and P from livestock production accounted for 57% and 39% of the total external input in crop-livestock system, and output of N and P as main animal products accounted for 60% and 33% of the output in crop-livestock system. All of these indicators indicated that Luancheng district was a typical high environmental loads peri-urban production system. From 1985 to 2014, manure N recycled rate decreased from 59% to 35%. Meanwhile, the nitrogen use efficiency (NUE) decreased from 45% to 43%, and the phosphorus use efficiency (PUE) decreased from 32% to 23% in the crop production during the same period. However, different with that of crop production, the NUE in animal production was increased from 14% to 30%, and the PUE of animal production was increased from 4.4% to 10%. For the whole crop-livestock production system, the NUE decreased from 41% to 36%, and the PUE decreased from 27% to 16%, respectively. In 2014, when 1 kg N was delivered into the crop products, 0.66 kg N lost to environment. Similarly, when 1 kg P was delivered into the crop products, 0.11 kg P lost to environment. The average N and P losses were 1.4 kg N and 1.8 kg P when 1 kg of N and P was retained in animal body, respectively. At the crop-livestock production level, the average N and P losses was 1.5 kg N·kg^-1 and 0.75 kg P·kg^-1. Ammonia was the major N loss pathway both in crop and livestock production, however, manure direct discharge was the main P loss pathway in the crop-livestock production system.【Conclusion】Driven by the urbanization and structure changes of crop-livestock system, the crop-livestock system in Luancheng district has been defined as the high input, high yield, low nutrient use efficiency, livestock dominated, high environmental risk typical and high environmental loads peri-urban production system during the past 30 years. The low nutrient use efficiency and high nutrient losses were due to the high livestock density, decoupled crop-livestock production and irrational nutrient management practices. Therefore, it is important to determine the reasonable livestock production capacity and improve the feed management and implement the whole chain manure management practices to achieve the sustainable crop-livestock production in Luancheng district.

Yield Gap of Alfalfa, Ryegrass and Oat Grass and Their Influence Factors in China

WEI ZhiBiao, BAI ZhaoHai, MA Lin, ZHANG FuSuo

Scientia Agricultura Sinica. 2018, 51(3):  507-522.  doi:10.3864/j.issn.0578-1752.2018.03.010

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【Objective】 Under the background of turning crop to forage and adjustment of plantation structure, the study on yield gap of alfalfa, ryegrass and oat grass is crucial for revealing yield potential. It can also provide a scientific basis for making high yield and high efficiency forage management strategies. 【Method】 The publications were collected by searching China National Knowledge Infrastructure and Web of Science with the keywords of “Alfalfa yield, Fertilizer”, “Ryegrass yield, Fertilizer”, “Oat grass yield, Fertilizer”, “Forage planting technology”, “Alfalfa, Fertilizer, China”, “Alfalfa, Irrigation, China”. A total of 176 published literatures were collected, including 101 articles for alfalfa, 51 articles for ryegrass and 24 articles for oat grass. This study summarized the yield potential and yield gap for three major cultivated forage species in China. Meta-analysis method was implied to quantify the effect of fertilization, sowing rate and irrigation rate on yield of three main cultivated forage species. This paper made a preliminary illustration about the factors that affect yield gap and ways to close the yield gap. 【Result】 The yield potential was 24 t·hm^-2 for alfalfa, 26 t·hm^-2 for ryegrass and 22 t·hm^-2 for oat grass. The farmer’s average yield of alfalfa, ryegrass and oat grass was 28%, 63% and 41%, respectively, of the yield potential. The fertilizer application rate of nitrogen (N) and phosphorus (P₂O₅), sowing rate and irrigation rate significantly affected forage yield. The optimized N and P₂O₅ application rate was 52 and 141 kg·hm^-2 for alfalfa, 585 and 46 kg·hm^-2 for ryegrass. For oat grass, the optimal nitrogen fertilizer application rate was not clear, but within the total amount of 225 kg·hm^-2, oat grass yield increased linearly with the increasing of N application rate. The optimal P₂O₅ application rate was 128 kg·hm^-2 for oat grass. The optimized sowing rate was 20 kg·hm^-2 for alfalfa, 30 kg·hm^-2 for ryegrass and 180 kg·hm^-2 for oat grass. The optimized irrigation volume was 5 737 m³·hm^-2 for alfalfa.【Conclusion】There was still a huge potential to increase yield of alfalfa, ryegrass and oat grass. The yield gap of alfalfa, ryegrass and oat grass was 17, 10 and 13 t·hm^-2. Furthermore, reasonable fertilizer application rate, seeding rate and irrigation volume are important to cut yield gap. By optimizing the fertilizer application rate, the yield of alfalfa, ryegrass and oat grass could increase by 3.4, 1.5 and 4.2 t·hm^-2. Suitable sowing rate could increase the yield by 60% for alfalfa, 78% for oat grass, but it was not enough to improve the yield of ryegrass only by adjusting the sowing rate. Optimal irrigation volume could increase the alfalfa yield by 9.1 t·hm^-2.

Spatial Characteristics of Nitrogen and Phosphorus Flow in Natural Grassland of China

WEI ZhiBiao, BAI ZhaoHai, MA Lin, ZHANG FuSuo

Scientia Agricultura Sinica. 2018, 51(3):  523-534.  doi:10.3864/j.issn.0578-1752.2018.03.011

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【Objective】The objective of this study is to quantify the spatial characteristics of nitrogen (N) and phosphorus (P) flow in natural grassland of China, and to provide a scientific basis for optimizing forage fertilization and increasing forage yield. 【Method】The input and output database of N and P in natural grassland of China was established, the nutrient balance budget, nutrient use efficiency and environmental emission characteristics in natural grassland of China were quantified by using NUFER model. 【Result】(1) In 2013, the total input of N and P in natural grassland of China was 5 034 Gg N and 318 Gg P, respectively. The N and P input per unit area in natural grassland was 19 kg N·hm^-2 and 1.2 kg P·hm^-2, respectively. The N deposition and the manure P applied accounted for 49% and 89% of total N and P input. The range of input (output) of N and P in natural grassland in different regions was 7.0-70 kg N·hm^-2 and 0.12-8.0 kg P·hm^-2; (2) In 2013, the use efficiency of N and P in natural grassland of China was 105% and 191%, respectively. There were great differences among different regions. The range of use efficiency of N and P was 67%-141%, 75%-538%, respectively; (3) In 2013, the environmental loss of N and P in natural grassland of China was 1.7 kg N·hm^-2 and 0.059 kg P·hm^-2, respectively. Ammonia emission and erosion were the main loss pathways of N and P in natural grassland, respectively. The N loss in natural grassland of Southwest and Northeast China was over 8.0 kg·hm^-2. The N loss of Northwest China was relatively low, which was less than 3.0 kg·hm^-2 on average. The N loss in Tibet plateau was the lowest, which was less than 1.0 kg·hm^-2. Spatial regularity of environmental P emission was similar to that of N emission; (4) In 2013, the total N and P deficit in natural grassland of China was 706 Gg N and 315 Gg P, respectively. The deficit per unit area of N and P was 2.7 kg N·hm^-2 and 1.2 kg P·hm^-2, respectively. The value of soil N accumulation in North and Southwest China was negative, and the soil N deficit in Chongqing, Jilin and Liaoning was more than 20 kg N·hm^-2. The value of soil nitrogen accumulation in West and Southwest China was positive, and the soil N accumulation in Guangxi and Yunnan was more than 5.0 kg N·hm^-2. Soil P accumulation in natural grassland of China was different from N accumulation. With the exception of Guangxi and Guizhou, all of other regions had a negative soil P accumulation. The P deficit of natural grassland in Chongqing was the largest, which was -3.7 kg P·hm^-2. 【Conclusion】In 2013, the total input of N and P in natural grassland of China was relatively low, about 50% of the N was input through the N deposition and 90% of the P was input by manure P applied. The soil accumulation of N and P in natural grassland of China was negative in 2013, and the N and P use efficiency was higher than 100%. The current grassland system was unsustainable and applying moderate chemical fertilizers was sensible. In 2013, the environmental loss of N and P in natural grassland of China was relatively low. The nutrient loss in Southwest China was larger than that in other regions. The spatial flow characteristics of N and P in natural grassland varied greatly among different regions.

Spatial Characteristics of Nitrogen and Phosphorus Flow in Cultivated Grassland of China

WEI ZhiBiao, BAI ZhaoHai, MA Lin, ZHANG FuSuo

Scientia Agricultura Sinica. 2018, 51(3):  535-555.  doi:10.3864/j.issn.0578-1752.2018.03.012

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【Objective】With the rapid development of animal husbandry in China and the increasing demand for forage, the adjustment of planting structure has become an inevitable trend. The objective of this study is to quantify the nitrogen (N) and phosphorus (P) spatial flow of cultivated forage, and to provide a scientific basis for increasing grassland productivity. 【Method】Taking alfalfa, ryegrass and oat grass as target forage species, the database of N and P input and output was established, the nutrient balance budgets, nutrient use efficiency and environmental emissions were quantified in cultivated grassland of China by using NUFER model. 【Result】 (1) In 2014, the total input (output) of N in alfalfa, ryegrass and oat grassland of China was 1 547, 236 and 67 Gg, respectively. The N input (output) of per unit area in alfalfa, ryegrass and oat grass grassland of China was 326, 427 and 217 kg N·hm^-2, respectively. The total input (output) of P in alfalfa, ryegrass and oat grass grassland of China was 323, 44 and 16 Gg and the P input (output) of per unit area was 49, 18 and 35 kg P·hm^-2, respectively. N fixation was the largest input item for alfalfa which accounted for 51% of the total N input into alfalfa grassland. N fertilizer was the largest input item for oat grass and ryegrass which accounted for 93% and 84% of the total N input into ryegrass and oat grass grassland, respectively. P fertilizer was the most important input of P in these kinds of forage. (2) In 2014, the nitrogen use efficiency (NUE) of alfalfa, ryegrass and oat grass grassland was 64%, 93% and 69%, respectively. The phosphorus use efficiency (PUE) was 28%, 77% and 34%, respectively. The NUE and pue varied greatly in different regions. (3) In 2014, the N loss of alfalfa, ryegrass and oat grass grassland per unit area was 23, 4.0 and 9.9 kg N·hm^-2 and the P loss of them was 2.6, 3.8 and 2.6 kg P·hm^-2, respectively. The N and P loss of alfalfa and ryegrass grassland in Southwest China was higher than that in other regions. The N and P loss of oat grass grassland in Western China was higher than that in other regions. (4) In 2014, the N and P accumulation of cultivated grassland were positive except for N accumulation in ryegrass grassland. The accumulation rate of alfalfa grassland in Western China was higher than that in Eastern China. There was no regular regional change of N and P accumulation for ryegrass grassland. The N and P accumulation rate of oat grass grassland in Tibet Plateau was higher than that in other regions. 【Conclusion】In 2014, there was a large gap of N and P input (output) for alfalfa, ryegrass and oat grass grassland in different regions of China. N fixation was the major way for alfalfa to acquire N nutrition, so alfalfa grassland management should reduce the input of N fertilizer. Oat grass and ryegrass mainly get the required nutrients by chemical fertilizer, so it should pay attention to fertilizer application for oat grass and ryegrass grassland. The NUE of target forage species was higher than 60%, but PUE was relatively low. Ryegrass grassland was deficient in N, and it is necessary to apply more nitrogen fertilizer. other cultivated grasslands had surplus of N and P in varying degrees, so the excessive application of fertilizer should be controlled.

Effects of Fertilization and Irrigation on the Carbon Footprint of Alfalfa in Gansu Province

LIU Song, WANG XiaoQin, HU JiPing, LI Qiang, CUI LiLi, DUAN XueQin, GUO Liang

Scientia Agricultura Sinica. 2018, 51(3):  556-565.  doi:10.3864/j.issn.0578-1752.2018.03.013

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【Objective】The objective of the study is to evaluate the carbon footprint (CF) of alfalfa production in different cropping patterns in Gansu Province, clarify the main process emitting greenhouse gases (GHG), analyze the effects of fertilization and irrigation on the CF, and investigate the potential measures for decreasing CF of alfalfa production in this province. 【Method】Life cycle assessment methodology combined with IPCC (2006) guide for calculating greenhouse gases emission in the field were used to quantify the CF of alfalfa production. Data were collected from farm survey in major regions of alfalfa cultivation in Gansu Province which covered 10 counties in the districts of Longdong, Longzhong and Hexi. Cropping pattern of alfalfa production in Gansu province was classified into four types according to the level of nitrogen application and irrigation, and the irrigation water source. The CF composition characteristics of four cropping patterns and the effect of nitrogen application rate and irrigation on productivity and CF of alfalfa were analyzed based on CF calculation model and input and output data of alfalfa production. Scenario analysis was used to estimate the GHG abatement potential through strategies such as decreasing chemical fertilizer application, improving fertilizer production technique, combining chemical fertilizer and organic fertilizer, and utilizing sprinkle and dripping irrigation. 【Result】CF of alfalfa production was 0.02, 0.19, 0.22 and 0.64 kg CO₂ eq·kg^-1 DM under four cropping patterns including NFNI (non-fertilization and non-irrigation), SFNI (spreading fertilization and non-irrigation), SFRI (spreading fertilization and river irrigation) and SFWI (spreading fertilization and well irrigation), respectively. The CF of alfalfa production in SFNI cropping pattern was significantly different from other cropping patterns except for SFRI. The main contributors of CF and their proportion to the total GHG emissions varied among different cropping patterns. For NFNI pattern, CF was mainly composed of GHG emissions from crop residues and the use of agricultural machinery. For SFNI and SFRI patterns, the major contributor of CF were chemical fertilizer production and nitrogen fertilizer application, followed by the use of agricultural machinery. The greatest GHG emissions source for SFWI pattern was electricity for irrigation, followed by chemical fertilizer production and nitrogen fertilizer application. Reducing the amount of applied nitrogen, combining chemical fertilizer with manure, and decreasing the GHG emission from nitrogen fertilizer production would decrease CF by 10.0%-18.0%, -3.0%-8.0% and 1.8%-5.8% in SFNI, SFRI and SFWI patterns, respectively. The water-saving irrigation (sprinkler irrigation and drip irrigation) would decrease the CF by 12.7%-38.5%.【Conclusion】 The alfalfa production and CF of four cropping patterns in Gansu province are different. The SFWI pattern got the highest production with high input, while its CF was significantly higher than that of other patterns. With the exception of NFNI pattern, excessive fertilizer was used in other three patterns. Reducing the amount of applied N fertilizer and the GHG emission from N fertilizer production will decrease CF of alfalfa production in Gansu province. The combination of chemical fertilizer and manure will decrease CF in SFNI and SFRI patterns, but also the yield of alfalfa hay. So, the optimal ratio of chemical fertilizer to manure should be investigated further. The water-saving irrigation will be the major mitigation measure in SFWI pattern, while the integrated abatement potential of GHG emission should be evaluated including emissions from the production of pipes used in sprinkler and drip irrigation.

Review on Ammonia Emission Mitigation Techniques of Crop-Livestock Production System

CAO YuBo, XING XiaoXu, BAI ZhaoHai, WANG Xuan, HU ChunSheng, MA Lin

Scientia Agricultura Sinica. 2018, 51(3):  566-580.  doi:10.3864/j.issn.0578-1752.2018.03.014

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Crop-livestock system includes two sub-systems of animal production and soil-crop production. Manure management is the most important part to connect animal production and soil-crop production. Ammonia emission occurred in the chain of livestock housing, manure storage, manure processing and application. Crop-livestock system was the great contributor to ammonia emission in the world, and currently higher ammonia emission made the local air quality worse. Ammonia emission mitigation options in crop production and the whole feeding-livestock housing-storage-processing-application chain of livestock production have been a hot topic for many years. In this study, we consider the whole manure management chain and fertilizer application when the ammonia mitigation techniques are summarized. In the past decades, plenty of ammonia emission mitigation researches have been conducted in America and European countries. Studies on ammonia mitigation technique mainly focused on fertilizer application in China, and the studies on livestock production chain in China just started in recent years. Here, ammonia emission mitigation techniques from the world were comprehensively reviewed in this study. The mitigation mechanisms, effects and feasibilities of the technique were discussed. We also presented further directions and significances of ammonia mitigation research. The suggestions are as follows: (1) The present study on ammonia emission mitigation mainly focus on specific part and single technique of crop-livestock system. However, the integrated mitigation options of the whole chain are lack especially in China. We suggest consider economic factors, gaseous emissions and animal welfare to create a comprehensive ammonia mitigation technique package. (2) China should vigorously support the study of ammonia emission mitigation techniques and related equipment. The studies should include the principles, regulations, costs and benefits analysis of ammonia emission mitigation techniques. Meanwhile it is also important to promote the extensions of ammonia mitigation techniques. (3) It is suggested that the subsidy policy of ammonia mitigation technique should be formulated to promote the mitigation of ammonia emission in crop and animal production.

Current Situation and Optimization Strategy of Phosphorus Recommendation Level and Phosphate Application of Feed in China

GUO YongQing, TU Yan, ZHANG NaiFeng, LIU GuoHua, TANG DeFu, WANG ZongYong, ZHONG Hao, LI YaoJi, MA Lin

Scientia Agricultura Sinica. 2018, 51(3):  581-592.  doi:10.3864/j.issn.0578-1752.2018.03.015

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【Objective】Phosphorus (P) is one of the essential mineral elements for animals. It plays an important role in the growth, development and production of livestock. However, the efficiency of P in animal production is very low, a large amount of undigested feed P excreted with manure, and the P enrichment in the environment resulted in serious P pollution, such as eutrophication. Feed P level and phosphate supplementation are closely related to the P use efficiency and manure P excretion. The objective of this study is to determine the status of P level and phosphate application of animal feed in China, and to provide a scientific basis for rational use of feed P resource and reduce the excretion of manure P. 【Method】 The variance of the P requirement recommended by American feeding standard and Chinese feeding standard, the actual P content and phosphate supplementation in the feed were studied in this research by conducting literature analysis, surveys, and experiments. 【Result】 For swine, compared to the Chinese standard, the current American standard recommends the P requirements as total P, standardized total tract digestible (STTD) P, and apparent total tract digestible (ATTD) P, with no recommendation for non-phytate P (NPP). For laying hens, broilers, meat ducks, the American standard lists NPP requirements, but not total P requirement. For dairy cattle, the total P requirement recommended by the Chinese standard is 31%, 74%, and 26% higher than the American standard for heifers, milking cows, and dry cows, respectively. Compared to the American standards, the current Chinese feeding standard is higher in the NPP requirement for laying hens (0.32% vs 0.25%), slaughter chickens (0.35%-0.40% vs 0.30%-0.35%), and meat ducks (0.35%-0.42% vs 0.30%-0.40%). The majority of phosphates used in feed in China is dicalcium phosphate (DCP), then the mono-dicalcium phosphate (MDCP) and monocalcium phosphate (MCP). The contents of phosphate, total P and NPP of same feed produced by different enterprises varied greatly. The use of calcium phosphate in commercial feeds in China was 8.8 kg·t^-1 in 2016 on average, decreasing from 12.0 kg·t^-1 in 2006. Total P requirement of animals and poultry used by the feed industry in 2016 was similar to that used in 2006 based on surveys, consistent with the Chinese standards. However, the NPP requirement used by the feed industry was higher than recommended by both the Chinese standards and the American standards for laying hens, growing pigs, and finished pigs.【Conclusion】The P requirements of dairy cows, laying hen, later stage of broiler, and meat duck recommended by Chinese feeding standard were higher than the American standard; the use of calcium phosphate in commodity feeds in China was 3.2 kg·t^-1 in 2016 lower than in 2006 on average; the NPP requirement used by the feed industry was higher than recommended by both the Chinese feeding standards and the American feeding standards for laying hens, growing pigs, and finished pigs. It is suggested that the study of phosphorus requirement should be carried out based on the animal varieties and feed characteristics in China, and to modify the recommended standards for phosphorus requirement of animals. At the same time, we need to adopt the measures of using the low-phosphorus diets, the high utilization rate of calcium phosphate and addition of phytase in feed to improve the efficiency of feed phosphorus utilization, and to reduce the P excreted with manure.

Trend Analysis, Policy Evaluation, and Recommendations of Agricultural Non-Point Source Pollution

JIN ShuQin, XING XiaoXu

Scientia Agricultura Sinica. 2018, 51(3):  593-600.  doi:10.3864/j.issn.0578-1752.2018.03.016

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【Objective】The paper makes a scientific judgement on the trend and impact of agricultural non-point source pollution (NPSP), which is important for policy strategy in the future. To better solve the current problems and correct policy deviations in a timely manner, evaluation on policy implementation is necessary. 【Method】A comprehensive review of the relevant policies of China in the field of agricultural non-point source pollution control since 1970s has been made. The current policies of agricultural non-point source pollution were evaluated with methods of documentary analysis, field survey, and literature review. 【Result】As the statistic and monitoring system being more complete, the data of emission quantity for agricultural non-point source pollution will get larger, and its impact on water quality will also be more directly. At present, agricultural non-point source pollution is concerned by the society and the government attaches great importance to it. At the same time, the demand for agricultural transformation is urgent. The top-level design of the policy is basically formed, but it is important to guard against formalism in the implementation of the policy. The realization of the goal of zero growth of chemical fertilizer is more certainly, while the zero growth target of pesticides faces more uncertainty, and all of them need to guard against falling into the ‘digital game’ trap. The pollution control of livestock and poultry is restricted and lack of motivation, which seriously hinders the comprehensive utilization of livestock and poultry manure. The ‘forbidden-burning’ policy on straw regardless of cost, spend a lot of manpower and material resources, which need to be reconsidered.【Conclusion】In the long run, the prevention and control of agricultural non-point source pollution need to make long-term preparation, improve the monitoring system, find out the actual situation, and avoid ‘numeric game’. The implementation of policies must be stressed. Supply side structural reform is necessary for agricultural inputs in order to reduce the quantity of chemical use. At the end of agricultural producing, reuse is the major outlet of the by-product such as straw, manure, et al. The public financial investment for agricultural non-point source pollution control should be increased, and matched with its emission ratio.