The Innovation Team of Improvement and Amelioration of Soil Fertility of the Institute of Agricultural Resources and Regional Planning (IARRP) of the Chinese Academy of Agricultural Sciences (CAAS) has quantified the optimal nitrogen application rate in China at county level, and further proposed supporting farmland management measures to improve yield and nitrogen use efficiency in addition to fertilization.

The results of the study, which were published in The Journal of Cleaner Production, can provide reference for the global rational use of nitrogen fertilizers.

According to professor Duan Yinghua, China's current nitrogen fertilizer application rate is high, and optimal nitrogen management is crucial for efficient crop production and agricultural pollution control. It is critical to address the dual challenges of food security and environmental protection by optimizing fertilization rates without changing farmers' operational practices.

The study quantified the relationship between nitrogen application and crop yield across China based on data from 35,502 field fertilization trials conducted between 2005 and 2015. In combination with the nitrogen balance conceptual model proposed by the EU Nitrogen Expert Group, the assessment focused on farmers' habits.

The results showed that smallholder farmers in China could actually produce more grain with less nitrogen fertilizer use only through optimizing nitrogen application rate. The yields of wheat, maize and rice were increased by 10% to 19% after optimizing nitrogen application, while nitrogen application was reduced by 15%–19% and nitrogen surplus was reduced by 40%. Beyond of optimizing nitrogen application rate, improved management practices were required in some areas to produce more grain with less pollution, which would need about 11.8 billion US dollars for the implementation and reducing N loss reduction by 1.75 million tons to the environment.

Ren Keyu, a doctoral student of the IARRP, is the first author, professor Duan Yinghua and Professor Gu Baojing from Zhejiang University are the co-corresponding authors. The research was funded by the National Key Research and Development Program, the National Natural Science Foundation of China, the Fundamental Research Funds of the Central-level Public Welfare Research Institute, and the GEF Project of the United Nations Environment Programme.

Paper link: https://doi.org/10.1016/j.jclepro.2022.132180