Cover Crops in Mono- and Biculture for Accumulation of Biomass and Soil Organic Carbon

Plant biomass production associated with soil organic carbon (C) accumulation is a critical challenge for sustainable agriculture development because soil quality degradation and organic carbon pool depletion have become a concern under some circumstances. To elucidate cover crops and their synergetic effects in biomass production and soil organic C improvement, legume and non-legume winter/summer cover crops, in mono- and biculture (mixture of legume/non-legume) were evaluated in the field and controlled (growth chamber) conditions. Under field conditions, biculture of sunn hemp and sorghum sudangrass produced 24.1 Mg ha−1 in contrast to 20.1 and 2.9 Mg ha−1 for each one alone; and biculture of okra and cowpea reached as much as 11.5 Mg ha−1 in contrast to 2.0 and 5.3 Mg ha−1 for each one in monoculture. After the growth of winter followed by summer cover crops, the soil organic C content increased with substantial quantities of plant biomass returned to the soil. The results suggest that both summer and winter cover crops demonstrate a promising potential in biomass C accumulation, thereby, can play an important role in soil fertility improvement to benefit the sustainable development of agriculture when appropriate types and combinations are selected.