Maize/cover crop intercropping mitigates soil erosion and enhances yield of ridge cultivation in Chinese Mollisol region

Abstract

Severe soil erosion has led to large-scale sloping farmland degradation and destruction in the Mollisol of Northeast China. Intercropping cover crops with the main crop is a potential agroecological practice to reduce soil erosion in the current intensive cropping systems, if the grain yield of the main crop is not compromised. In this study, we intercropped six cover crops (calopo, pigeon pea, Chinese milk vetch, oilseed rape, oilseed radish and woad) with contrasting functional traits in the furrow of maize ridge cropping system to evaluate their effects on maize grain yield and soil erosion. The field experiment was conducted in 2022 and 2023 on a 4.2° slope farmland in the Mollisol region of Northeast China. The results showed that the effects of cover crop intercropping on maize grain yield and soil erosion control varied with cover crop species and their phenological and morphological characteristics. Cover crops, which emerged late and had relatively low plant height and aboveground biomass in the early growth stages of maize, had no significant effect on maize growth. In terms of soil erosion control, cover crops with higher stem density and stem diameter density provided more effective soil erosion control. Based on agronomic and environmental evaluations, Chinese milk vetch and woad are the most suitable cover crops for maize/cover crop intercropping systems, which increased maize yield by 0.6–13.5% and reduced annual soil loss by 80.6–88.3%. These results justify that intercropping suitable cover crops with maize is an effective soil erosion control strategy that ensures high yield production without changes in existing mechanized farming practices on sloping farmland in the Mollisol region of Northeast China.