Agronomic and environmental benefits of nutrient expert on maize and rice in Northeast China.

Agricultural production in China is facing great challenges to ensure food security and cleaner environment; further improvements are therefore required in crop nutrient management to increase grain yield and nutrient use efficiency while synchronously reducing environmental pollution. In this study, a total of 87 site-years of on-farm experiments were conducted from 2013 to 2018 in the main agro-ecological areas in Northeast China, to evaluate the agronomic and environmental benefits of nutrient expert (NE) system in maize and rice production. Results showed that NE had general and significant advantages in agronomic and environmental benefits relative to FP, by dramatically reducing N and P fertilizer inputs and optimizing nutrient management. As compared to FP, on average, NE increased grain yield by 8.4% and 6.6% significantly higher grain yield and N uptake for maize, respectively, while it obtained equal yield performance and 3.0% higher N uptake for rice, and consequently resulted in significantly higher N use efficiency. Environmental effects assessment showed that NE reduced substantially reactive N losses and greenhouse gas emissions by 46.9% and 37.2% for maize, respectively, and 10.1% and 6.6% for rice, respectively. Regression analysis indicated that NE effectively improved N use efficiency and mitigated environmental pollution was mainly associated with increasing plant N uptake and reduced N surplus. As compared to fertilization recommendation based on soil testing, NE system showed higher N use efficiency and better environmental benefits for both maize and rice. In conclusion, our results demonstrated that NE system is a feasible and promising approach to optimize crop nutrient management and promote cleaner agricultural production in Northeast China.