Effects of optimized fertilization on yield, nutrient balance, and eco-environmental benefits in wheat-maize rotation system

The wheat-maize rotation system in the North China Plain is the main planting pattern that plays a key role in ensuring food security in China. An 8-year positioning experiment with a randomized block design was performed, comprising three treatments: no-fertilizer application control (CK), optimized fertilizer (OPT), and farmers’ practices (FP). The experiments analyzed the effects of OPT and FP on the yield, nutrient balance, greenhouse gas emissions, and economic benefits of the wheat-maize rotation system. The results showed that the yields of OPT increased by 4.3%, 5.3%, and 4.8% compared to FP in wheat, maize, and year-round rotation, respectively. Accordingly, the partial factor productivity of N increased by 39.1%, 31.7%, and 35.9%, respectively. The partial factor productivity of P increased by 39.1%, 40.4%, and 39.8%, respectively. The partial factor productivity of K was reduced by 47.8%, 47.3%, and 47.6%, respectively. The greenhouse gas emissions were reduced by 21.7%, 21.1%, and 21.4%, respectively. The greenhouse gas emission intensity was reduced by 27.0%, 27.5%, and 27.3%. Net profits increased by 11.2%, 11.4%, and 11.3%, respectively. Agronomy costs were reduced by 3.7%, 2.1%, and 3.1%, respectively. The environmental costs were reduced by 28.4%, 17.3%, and 22.1%, respectively. Compared with the FP treatment, the year-round OPT treatment reduced the surplus of nitrogen by decrement of 105 kg·hm⁻², i.e., 46.3%. The surplus phosphorus was reduced by 48 kg·hm⁻² i.e., 53.3%. The surplus of K of OPT and FP was 59 kg·hm⁻² and −1 kg·hm⁻², respectively. OPT met the requirements of crop growth better than FP. At the end of 8 years of wheat-maize rotation, the soil organic matter content in OPT treatment increased by 5.3% compared to that in FP. Compared to that of FP, available K increased and P reduced by 12.3% and 27.8%, respectively. In conclusion, compared with FP treatment, OPT treatment has the advantages of high yield, high profit, and environmental friendliness. Therefore, this study provides a scientific basis for the efficient and green product.