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| Nitrogen flow characteristics and fertilizer reduction potential of crop-livestock systems in Shandong Province under the policy of fertilizer reduction and efficiency increase |
| Received:January 22, 2025 |
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| KeyWord:crop-livestock systems;NUFER model;fertilizer reduction and efficiency increase;nitrogen use efficiency;fertilizer reduction potential |
| Author Name | Affiliation | E-mail | | WANG Xinya | Institute of Agricultural Resources and Environment, Hebei Academy of Agriculture and Forestry Sciences, Shijiazhuang 050051, China
College of Resources and Environment, Qingdao Agricultural University, Qingdao 266109, China
Institute of Environment and Sustainable Development in Agriculture, CAAS, Beijing 100081, China | | | ZHAO Tongtong | Institute of Agricultural Resources and Environment, Hebei Academy of Agriculture and Forestry Sciences, Shijiazhuang 050051, China | | | HUANG Shaohui | Institute of Agricultural Resources and Environment, Hebei Academy of Agriculture and Forestry Sciences, Shijiazhuang 050051, China | shaohui1988@sina.com | | YANG Wenfang | Institute of Agricultural Resources and Environment, Hebei Academy of Agriculture and Forestry Sciences, Shijiazhuang 050051, China | | | ZHANG Qingwen | Institute of Environment and Sustainable Development in Agriculture, CAAS, Beijing 100081, China | zhangqingwen@caas.cn | | JIA Liangliang | Institute of Agricultural Resources and Environment, Hebei Academy of Agriculture and Forestry Sciences, Shijiazhuang 050051, China | |
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| Abstract: |
| By collecting data from statistical yearbooks and literature, the NUFER model was employed to analyze the nitrogen flow characteristics in the cropland-livestock systems of Shandong Province for three typical years：2007（the amount of nitrogen fertilizer had reached its peak）, 2015（the usage rate of nitrogen fertilizer was slow）, and 2022（the amount of nitrogen fertilizer was decreasing rapidly）. We quantified the nitrogen utilization rate of the system and the environmental loss rate and evaluated the application effect of fertilizer reduction and efficiency increase policy, and further clarified the potential of fertilizer reduction and efficiency increase in the croplivestock systems in Shandong Province through setting three scenario analyses of reducing soil surplus（S1）, increasing the proportion of livestock and poultry manure returned to the field（S2）, and optimizing the structure of animal feed（S3）. In 2007, 2015 and 2022, the total nitrogen inputs of crop-livestock systems in Shandong Province were 3.716 million tons, 3.648 million tons and 2.994 million tons respectively, showing a downward trend. Chemical fertilizers accounted for the highest proportion, which were 69.9%, 61.9% and 55.6% respectively, and the usage of chemical fertilizers gradually decreased. In the three-year period, the nitrogen use efficiency in the cropping system（NUEc）was 36.3%, 42.5% and 54.7% respectively. The nitrogen use efficiency in the livestock system（NUEa）was 27.9%, 19.0% and 22.8% respectively. The nitrogen use efficiency in the crop-livestock systems（NUEc+a）was 31.7%, 33.4% and 44.6% respectively, gradually rising and reaching 44.6% in 2022. In 2022, the nitrogen accumulation in soil reached 0.257 million tons, accounting for 8.6% of the total input, while the total amount of nitrogen environmental loss was as high as 1.270 million tons, accounting for 42.4% of the total input. Among environmental loss, ammonia volatilization（including ammonia volatilization from crop and livestock manure）and the discharge and stacking of livestock manure in water bodies were the two loss pathways with the largest proportions. In the three years, the proportions of ammonia volatilization in the total environmental emissions were 45.8%, 49.0%, and 54.5% respectively, and the proportions of the discharge and stacking of livestock manure into water bodies were 16.8%, 21.5%, and 25.6% respectively. By reducing the nitrogen accumulation in the soil, this region has the potential to reduce the application of nitrogen fertilizer by 29.0%. At this time, the total nitrogen input in the crop-livestock systems was 2.511 million tons, the NUEc+a increased from 44.6% to 53.1%, the nitrogen cost of food decreased from 2.2 kg·kg-1 to 1.9 kg·kg-1, and the environmental loss decreased from 1.270 million tons to 1.044 million tons. Further increasing the proportion of livestock manure returned to the fields could reduce the usage of chemical fertilizers by 8.6%, increase the NUEc+a by 2.3 percentage points, and reduce environmental loss by 9.8%. Continuing to optimize management and adjust the structure of animal feed, there would be a 34.3% potential for reducing nitrogen fertilizer application in this region. Meanwhile, the total nitrogen input in the crop-livestock systems reduced to 2.263 million tons. The NUEc+a could increase to 58.9%. The nitrogen cost and environmental loss were 1.7 kg·kg-1 and 0.796 million tons respectively, with a decrease of 22.7% and 37.3% compared with 2022. From 2007 to 2022, the chemical fertilizers application rate in Shandong Province showed a downward trend. The overall nitrogen input in the crop-livestock systems also gradually decreased. The NUEc+ a showed an upward trend, while the environmental loss showed a downward trend. It has achieved remarkable results in fertilizer reduction and efficiency increase in Shandong Province, providing important support for the green development of regional agriculture. In addition, we highlights that the maximization of the potential for chemical fertilizer reduction can be realized across the province throughout the layout of different regions, policy guidance and technical support, as well as the coordinated advancement of the S1, S2 and S3 technical paths. |
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