Life cycle assessment of a long-term multifunctional winter wheat-summer maize rotation system on the North China Plain under sustainable P management

Abstract

In sustainable agriculture, sufficient crop yields and nutrients must be produced while maintaining environmental protection. Considering the role of phosphorus (P) fertilizer in influencing crops yield and environmental security, life cycle assessment was used to examine the environmental impacts of long-term P application on the grain yield and nutritional quality of winter wheat and summer maize. Thus, a long-term field experiment with six P application rates for winter wheat (0, 25, 50, 100, 200, and 400 kg P ha^-1) and summer maize (0, 12.5, 25, 50, 100, and 200 kg P ha^-1) was conducted on the North China Plain (NCP). The results showed that the cradle-to-farm gate eutrophication potential (EP), energy depletion (ED), and P depletion (PD) were significantly affected by the P application rate applied in winter wheat and summer maize production. The critical P rate required to ensure food security for wheat and maize was in line with the optimal rate for sustainable environmental development in terms of grain production and nutrient levels. On the NCP, the ED and PD of summer maize with optimized P management over 10 years were less than those of winter wheat regardless of using yield or nutrient level as the functional unit. However, the EP of the nutrient supply in winter wheat was less than that in summer maize under optimized P fertilization. The specific nutritional components that limited improvements in environment of wheat and maize production under the optimal P rate were energy (calories) and protein, respectively. In conclusion, in a multifunctional winter wheat-summer maize rotation system, optimized P fertilization (50 kg ha^-1 for winter wheat and 25 kg ha^-1 for summer maize) combined with the planting of high-yield wheat varieties and high-protein maize varieties showed great potential to reduce the environmental impacts of wheat and maize production.

Keywords: Grain yield; Life cycle assessment; Nutritional yield; P fertilizer; Summer maize; Winter wheat.