东北黑土区典型县域农牧系统养分流动特征分析

Nutrient flow characteristics analysis of typical county in crop-livestock systems in black soil region in Northeast China

在保障粮食安全的前提下,东北黑土区作物和畜牧生产的耦合促进了农业绿色发展。本研究选择位于东北黑土区的吉林省农安县为研究区域,以农牧系统为研究边界,通过实地调研、统计数据和文献,结合食物链养分流动模型(NUFER:NUtrient flows in Food chains,Environment and Resources use)定量分析1990—2020年农牧系统氮磷养分流动、利用效率和环境损失,探究气候和社会经济因素对氮磷排放的驱动作用,并设置平衡施肥(减少化肥施用)和有机肥替代(提升有机物料替代)两种情景评估该县减排潜力。结果表明,相对于1990年,2020年农安县农牧体系氮磷输入量分别下降45%和23%,其中化肥施用是最大的输入项。作物和农牧系统养分利用率波动增加,而畜禽系统养分利用率下降并逐渐趋于稳定。农牧体系氮磷损失量较1990年分别减少41%和增加29%。农田氨挥发、径流侵蚀和畜禽粪便直排为主要排放途径。通过平衡施肥和有机替代,土壤氮磷积累处于较低水平,至2030年农安县化学氮肥有80%的减施潜力,化学磷肥有85%的减施潜力,且氮磷养分环境排放均减少67%,作物和农牧系统养分利用率均增长50%以上。综上,农安县农牧体系未来可通过增加秸秆和粪便还田量提升化肥减施潜力。东北黑土区应继续深化化肥零增长政策,推行有机废弃物资源化利用,实现农牧系统协同优化发展。

The integration of crop and livestock production promotes agricultural green development and guarantee food security in black soil region in Northeast China.In this study,Nong’an County,Jilin Province,which is located in black soil region in Northeast China,was selected as the study boundary.Quantitative studies for nitrogen and phosphorus flows,utilization efficiency as well as environmental losses in crop-livestock systems from 1990 to 2020 were conducted through field research,statistical data and literature,combined with the NUFER model(NUtrient flows in Food chains,Environment and Resources use).The present study explored the impacts of climate and socio-economic factors on nitrogen and phosphorus emissions.Furthermore,two sets of scenarios of balanced fertilization(reduction of fertilizer application)and organic substitution(increase of organic material substitution)were set up to assess the county’s emission reduction potential.The results showed that,compared to 1990,nitrogen and phosphorus inputs to crop-livestock systems for Nong’an County in 2020 decreased by 45%and 23%,respectively,with chemical fertilizer application as the largest input.The nutrient utilization efficiency of crop system and crop-livestock systems increased fluctuatingly,while nutrient utilization efficiency of livestock system decreased and tended to remain stable.The nitrogen and phosphorus losses of crop-livestock systems decreased by 41%and increased by 29%compared to 1990,respectively.Ammonia volatilization from farmland,runoff and erosion,and livestock manure discharge were the major contributors to nutirent losses.Through balanced fertilization and organic substitution,it is predicted that by 2030,Nong’an County will have the potential to reduce the application of chemical nitrogen fertilizer by 80%and chemical phosphorus fertilizer by 85%,with low levels of soil nitrogen and phosphorus accumulation,and the environmental emissions will be reduced by 67%,the nutrient utilization efficiency of crop system and crop-livestock systems will increase by more than 50%.In conclusion,crop-livestock system of Nong’an County can enhance the potential for fertilizer reduction in the future by increasing the amount of straw and manure returned to the field.The black soil region in Northeast China should continue to deepen the policy of zero growth of chemical fertilizer,and promote the utilization of organic waste to guarantee a synergistically optimized crop-livestock systems.