Maximizing Cover Crop Biomass Production for Biofuel.

Producing biofuel from renewable sources such as corn stover is a worthy endeavor. However, other sources of biofuel feedstocks exist including cover crops (CC). Using CC for biofuel must balance achieving sufficient biomass for biofuel with crop yields. The objective of this review is to synthesize available literature on biomass of CC under different management techniques, assess the effect of CC management on primary crop yield, and highlight research needs. Different CC management techniques such as interseeding into primary crops or terminating just before primary crop planting could increase CC biomass production by up to 16 times that of terminating 30 d before planting primary crops. Planting CC after corn silage or wheat can result in CC biomass yield of >4 Mg ha^-1_. Cover crop biomass production with summer CC may achieve up to 9 Mg ha^-1 after just three mo after planting. It appears that significant potential exists to harvest CC biomass for biofuel; however, this biomass production must be balanced with primary crop yield. Studies evaluating interseeding CC into primary crops are very limited, but studies evaluating early vs. late termination of CC have shown limited impact to primary crop yield in non-water limited regions. However, in water limited regions, not only may CC biomass be limited, but impacts to crop yields can occur, but may not occur in every year. Overall, opportunities to use CC biomass for biofuel exist, but must be balanced with the primary crop yield and site characteristics.