Meta-Analysis of Yield Effects and Influencing Factors of Cover Crops on Main Grain Crops in China

The objective of this study was to clarify the effect of cover cropping on the yield of main grain crops in China, and to investigate the significant influencing factors, so as to provide a scientific basis for the promotion and application of cover crops in China.

A Meta-analysis including data from 903 pairwise observations from 137 publications from 1980 to 2022 was conducted to elucidate the effect of “fallow” versus “cover cropping” on yield of main grain crops. Meta regression was also conducted to explore the factors influencing the effect of cover crops on grain crops yield.

Under cover crops, grain crop yields increased significantly by 12.2% compared to fallow, with wheat, rice and maize yields increasing significantly by 9.5%, 11.9%, and 19.6%, respectively. In addition, grain crop yields increased by 9.5% and 12.4% for winter and summer cover crops, respectively. Among the different types of cover crops, leguminous cover crops increased grain crop yields by 12.9% (February orchid 14.2%, Chinese milk vetch 11.8%, vetch 9.5%, pea 7.8%, soybean 7.4%), while cruciferous and gramineous cover crops increased grain crop yields by 9.3% and 8.3% (rape 7.0%, ryegrass 7.9%), respectively. However, compared with pure stands, cover crop mixtures more markedly increased grain crop yield by 17.3%. Furthermore, cover cropping years and sunshine hours significantly increased the effect of cover crops. High precipitation and temperature increased the effect of cover crops at high latitudes, while high precipitation and temperature decreased the effect of cover crops at low latitudes.

During the fallow period, cover crops mixtures contribute to increase grain crops yields, reduce surface exposure and make full use of solar, thermal, water and soil resources, especially during the northern summer and southern winter.