Relating Soil Organic Carbon Fractions to Crop Yield and Quality with Cover Crops

Abstract

Cover crops provide many soil and environmental benefits, such as reducing soil erosion, increasing soil organic matter, decreasing nitrogen (N) leaching, and enhancing biodiversity compared to no cover crop or bare fallow. There is little information about how soil organic C fractions relate to crop yield and nutritional quality as influenced by cover crops. This study analyzed the effect of cover crop species on cover crop biomass yield and N accumulation, soil labile and non-labile C fractions, and their relationship with succeeding crop yields and N uptake from data collected around the globe. The results showed that a mixture of legume and nonlegume cover crops increased cover crop biomass yield and soil organic C compared to legume or no cover crop. The mixture also increased cover crop biomass N accumulation compared to nonlegume or no cover crop and produced similar or greater succeeding crop yields and N uptake than nonlegume or no cover crop. Soil organic C and labile C fractions were nonlinearly related to crop yield, except KMnO4-extractable C, which was linear. However, the relationships showed opposing trends. A mixture of legume and nonlegume cover crops can enhance soil organic C fractions and sustain succeeding crop yields and quality compared to either species alone or the control without cover crop. Succeeding crop yields due to cover crops increased when soil organic C was ≥12 g C kg−1, but crop yields varied with labile C fractions.