Diversifying wheat-based cropping systems with pulse crops enhances ecosystem services

Abstract

Pulse crops are commonly used to improve nitrogen management and diversify cereal-based cropping systems. However, integrated assessments of diversified rotations with pulse crops using plant, soil, and environmental quality indicators remain limited and relatively underexplored. A comprehensive evaluation of such diversified rotations based on agronomic performance, economic returns, and environmental sustainability over time is essential for enhancing cropping system resilience. An eight-year study (two cycles of 4-year rotation) was conducted at two locations to determine the effects of diversification with pulses on ecosystem services indicators including productivity, resource use efficiency, soil carbon, soil nitrogen, carbon footprint, and economic returns. Four cropping systems were evaluated, including a low-diversified rotation of lentil-wheat-lentil-wheat, a moderately diversified rotation of pea-wheat-lentil-wheat, a highly diversified rotation of pea-mustard-lentil-wheat, and a wheat monocrop control. At the 4-year rotation level, diversified rotations increased yield by 22–36%, water use efficiency by 31–42%, energy productivity by 78–86%, and economic returns by 46–65%, compared to the wheat monocrop. Additionally, diversified rotations resulted in net CO₂ withdrawal when accounting for carbon sequestration in the soil. There was no difference between moderately and highly diversified rotations, suggesting that a large portion of diversification benefits can be achieved at the moderately diversified rotation level. Compared with the wheat monocrop, diversified rotations reduced nitrogen fertilizer inputs and resulted in a 10–31% lower partial nitrogen balance at the end of 8-year rotations. Moreover, diversifying cropping systems with pulse crops had no adverse effect on soil organic carbon, despite relatively low straw returns from pulse crops. These results, assessed using multiple system indicators at both the crop phase and rotation levels, reveal that diversifying rotations with pulse crops, even at a moderate level, can effectively improve the ecosystem services, contributing to the sustainability of cropping systems.