Optimized planting structures maintain system yield and economic benefits with less nitrogen footprint

Contexts: The Huang-Huai-Hai Plain in China relies heavily on the winter wheat-summer maize rotation for grain production. However, this cropping system faces challenges regarding its sustainability due to significant environmental costs. Objectives: This study aims to evaluate the nitrogen footprint of different cropping systems, compare their economic benefits, and identify alternative summer crops that can optimize system yield, economic advantages, and environmental impact. Methods: A three-year field experiment was conducted to compare the economic and environmental impacts of three cropping systems: winter wheat-summer maize (W-M), winter wheat-summer soybean (W-S), and winter wheat-sweet potato (W-SP). The experiment involved assessing yield, inputs, and outputs, and conducting a comprehensive nitrogen footprint analysis for each system. Results: Over the three experimental years, the W-S system showed the highest yield improvement for winter wheat. The W-SP system had the highest annual maize equivalent yield and total income but incurred the highest total annual cost compared to the other two systems. However, the W-SP system demonstrated the highest annual average economic profit performance, nearly double that of the other two systems. The nitrogen footprint analysis revealed that both the W-S and W-SP systems reduced reactive nitrogen emissions compared to the W-M system. Notably, the W-S system managed to reduce the nitrogen footprint by 34%. The average nitrogen footprint emissions scores for W-M, W-S, and W-SP systems were 2.1, 2.3, and 3.5, respectively. Conclusions: Among the three systems, the W-SP system achieved the highest economic benefits but also had the greatest negative environmental impact. The W-S system demonstrated a significant reduction in reactive nitrogen loss while maintaining productivity, indicating its potential for mitigating negative environmental impacts. Significance: Our three-year field study highlights the advantages of the W-S system in reducing the nitrogen footprint and its potential contribution to sustainable agricultural development in the Huang-Huai-Hai Plain.