Improving nitrogen use efficiency and reducing environmental cost with long-term nutrient expert management in a summer maize-winter wheat rotation system

Excessive fertilization, poor management, low nitrogen (N) use efficiency and heavy pollution are the current issues that exist in intensively cultivated summer maize-winter wheat rotation system in China. To address these problems, we adopted the Nutrient Expert (NE) decision support system and compared it with the Farmer's Practice (FP). We explored the effects of NE and FP on grain yield, N use efficiency, soil N accumulation, environmental cost, and profitability in the rotation system from 2009 to 2018. The results showed that there was no significant yield difference between the NE (14.4 Mg ha- 1) and FP (14.3 Mg ha- 1), while reducing N application by 23.1 % in NE. Compared with the FP treatment, the NE increased the apparent recovery efficiency of N (apparent REN), accumulated recovery efficiency of N (accumulated REN), agronomic efficiency of N (AEN) and partial factor productivity of N (PFPN) by 25.0 %, 26.8 %, 31.1 % and 32.1 %, respectively, which also indicated a less N loss achieved by NE. The NE resulted in less N accumulation in the soil profile than FP, with reductions of 32.1 % and 44.2 % in the 0-100 cm and 60-100 cm soil layers, respectively. Moreover, calculations of economic benefit that considered the environmental cost showed that NE had an economic advantage (13.8 % of increase in net income; and 27.2 % of decrease in environmental cost) over FP. This study proved that long-term NE management is a sustainable management approach with advantages in maintaining grain yield, improving N use efficiency and profitability, and reducing environmental cost for the summer maize-winter wheat rotation system.