Cumulative impact of cover crops on soil carbon sequestration and profitability in a temperate humid climate.

Although soil C sequestration with cover crops (CCs) has been linked with the potential of CCs in climate change mitigation, the long-term usage of CCs on soil C storage and farm-based economics have been widely overlooked. Therefore, in a CC experiment established in 2007 in a temperate humid climate, four CCs and a no-CC control were compared to evaluate their potential to sequester C and provide economic returns. Total amount of plant C added to soil with CCs translated into greater soil organic carbon (SOC) content by 10-20 Mg C ha-1 than the no-CC control across both sites. Greater crop yield and reduced yield variability with CCs suggest the long-term potential of CCs in increasing agroecosystem resiliency. Moreover, greater profit margins with CCs in processing vegetable crops but not grain and oilseed crops indicate CC effects on crop profitability are dependent on the production system. Our study results indicated that the loss in profit margins with CC usage in grain and oilseed crops might be overcome with C pricing (at $50 Mg-1) on quantity of C sequestered after 9 years of CCing; thus, providing financial compensation to growers may be a mechanism to encourage CC adoption.