Location: National Soil Dynamics Laboratory
Title: Cover crop biomass harvest for bioenergy: implications for crop productivity Authors
Submitted to: Sustainable Feedstocks for Advanced Biofuels
Publication Type: Abstract Only
Publication Acceptance Date: August 12, 2010
Publication Date: January 15, 2011
Citation: Arriaga, F., Balkcom, K.S., Duzy, L.M. 2011. Cover crop biomass harvest for bioenergy: implications for crop productivity. Sustainable Feedstocks for Advanced Biofuels. Available at: http://www.swcs.org/documents/filelibrary/roadmap/SFAB_Program_and_Abstract_Book__FIN_8607CF9B02A16.pdf Technical Abstract: Winter cover crops, such as rye (Secale cereale), are usually used in conservation agriculture systems in the Southeast. Typically, the cover crop is terminated two to three weeks before planting the summer crop, with the cover biomass left on the soil surface as a mulch. However, these cover crops can produce a large amount of dry biomass (>2 ton/ha) if managed properly. Therefore, a study was established in a coastal plain soil of Alabama to determine the potential impacts of cover crop biomass harvest on productivity and soil quality. Results thus far indicate that full benefits are achieved when the cover crop is left on the field as mulch. Cotton (Gossypium hirsutum) yields were between 17 and 28% greater with the cover crop left on the soil surface when compared to no cover in the first four years of this study. Cover crop harvest reduced yields compared to retaining the cover biomass; however cotton yields were between 2 and 11% greater than with no cover. Additionally, differences on soil carbon were observed after only two years. Total soil carbon and particulate organic matter contents on the surface 2.5-cm of soil were significantly greater with cover retained compared to cover harvested and no cover. Similarly, carbon contents of the harvested cover crop treatment were significantly greater to no cover at this depth. There were no differences in carbon content between cover retained and harvested at the 2.5 to 5-cm depth, but these were significantly greater than the no cover control. A system that includes the harvest of cover crop biomass may be feasible for the Southeast since the cover can still provide some benefits to the agroecosystem, such as protecting the soil from erosion during the winter months, while at the same time potentially provide producers with an additional source of income. Producers of this region may be able to harvest cover crop biomass and still maintain productivity.