As concern remains over the need to convert millions of acres of crop land to meet the ever-increasing biofuel demand, a new study has found pumpkins could provide the answer to sharing between food and fuel.
Researchers understand that biomass feedstocks will need to come from many different sources, including crop residues, forest residues, and municipal waste, said Marty Williams, a University of Illinois crop scientist and ecologist with the USDA-Agricultural Research Service. The use of double-cropping systems – a winter annual biomass crop is grown then harvested in the spring, followed by a summer annual crop – has been suggested as an additional option.
Knowing that many large-seeded vegetables in the US Midwest must be planted later than agronomic crops into warmer soils, Williams was interested in the possibility of developing a bioenergy feedstock/vegetable double-cropping system. He explained that no such system had so far been developed and tested.
“Some vegetables have relatively short growing seasons, too. Rather than the standard fallow period for certain vegetables, what about integrating a bioenergy crop as a part of a double-cropping system?” Williams said.
Williams chose a vegetable crop popular in the state of Illinois, pumpkin, to be used in the double-cropping system study. “We took a fairly simplistic look at comparing this bioenergy/vegetable double-cropping system with traditional vegetable production using processing pumpkin,” Williams explained. “Illinois leads the nation in pumpkin production, providing some 90 percent of the processing pumpkin in the United States.”
Field trials were conducted over three environments. During the study, Williams compared crop productivity and weed communities in four different pumpkin production systems, varying in tillage, cover crop, and bioenergy feedstock/pumpkin double-cropping. A fall-planted rye (Secale cereale) mix was used as the biomass feedstock.
“In the end, winter rye may not be the best feedstock crop to use,” he explained. “It was more of a model crop for us for our system. It grows well and has several desirable traits. Seed is relatively inexpensive and the plant is hardy.”
Interestingly, the researchers saw pumpkin yields in the double-cropping system were comparable to conventional pumpkin production. However, the biomass feedstock also yielded an average of 4.4 tons per acre of dry biomass prior to pumpkin planting.
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Pumpkin image via Shutterstock.