Enhancing sustainability in the new variety-based low emergy system for maize production by nitrogen optimization

Global agriculture is confronted with multiple challenges in meeting the increasing demand for food production while adhering to planetary boundaries set to achieve the United Nations Sustainable Development Goals. Here, the challenge is addressed by proposing a new variety-based low emergy system (LES) for maize production through nitrogen (N) optimization. It is found that the LES and the current farmers' system (CFS) in North China Plain achieve similar grain yields (>11.2 Mg ha−1). The optimized N rate averages 157 kg N ha−1 for the new variety in LES, 41.85 % decreases compared to CFS with a traditional variety (270 kg N ha−1). The LES with new variety exhibits a 6.7 % higher grain protein concentration, attributed to increased N remobilization from stem as demonstrated by both field and 15N tracer experiments. The implementation of the LES with optimized N fertilization resulted in 18.2 % improvement in sustainability (emergy sustainability index) compared to CFS, while simultaneously reducing N and carbon footprints, ecological and human health costs by 33.0%–39.3 %. These findings demonstrate that the proposed system provides better coordination between grain yield, resource input and emergy cost to ensure both food and environmental securities for Sustainable Development Goals.