Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/18/2014
Publication Date: 5/1/2014
Citation: Williams, M. 2014. A bioenergy feedstock/vegetable double-cropping system. Industrial Crops and Products. 59:223-227. Interpretive Summary: In order to meet the mandate set forth by the Energy Independence and Security Act of 2007, millions of acres of U.S. cropland are likely to be converted to perennial bioenergy crops. Bioenergy double-cropping systems in the Midwest may ease competition of land for fuel versus land for food by growing a winter annual bioenergy feedstock crop followed by a summer annual food crop. In concept, certain vegetable crops may fit bioenergy double-cropping systems well; however, none of these systems have been developed or tested. This work examined the agronomic performance of a bioenergy double-cropping system in comparison to several conventional vegetable production systems. Using pumpkin as a model vegetable crop, the winter annual bioenergy feedstock system resulted in less late-spring soil nitrogen and a higher total farmgate value, compared to conventional pumpkin production. The impact of this work is that it demonstrates potential viability of a new approach to meeting demands of both fuel and food production in the 21st century.
Technical Abstract: Certain warm-season vegetable crops may lend themselves to bioenergy double-cropping systems, which involve growing a winter annual bioenergy feedstock crop followed by a summer annual crop. The objective of the study was to compare crop productivity and weed communities in different pumpkin production systems, varying in tillage, cover crop, and bioenergy feedstock/pumpkin double-cropping. Using a fall-planted rye (Secale cereale) + hairy vetch (Vicia villosa) mixture as a candidate feedstock, on average 9.9 Mt ha-1 of dry biomass was produced prior to pumpkin planting. Pumpkin yields in the cover crop system, which involved leaving the bioenergy feedstock on the soil surface, ranged from 49 to 65% of the conventional pumpkin system. When the bioenergy feedstock was removed, pumpkin yields in the feedstock tillage system were comparable to the conventional pumpkin system. Weeds remained problematic in all cropping systems; however, cropping systems without tillage (i.e. no-tillage and feedstock no-till systems) had among the highest weed population densities in pumpkin. The feedstock tillage system reduced potentially leachable soil N in the spring, produced enough bioenergy feedstock to theoretically yield an estimated 3,260 liters of ethanol ha-1 without negatively affecting processing pumpkin yield, and had a farmgate value comparable to, or greater than, the conventional pumpkin production system currently used by growers.