Establishment of switchgrass in corn across a landscape gradient: Establishment, yield, and quality of biomass feedstock
Biofuel production in the United States is expected to offset a significant portion of current fuel use through continued use of corn (Zea mays L.) grain and increasingly from alternative feedstocks. Switchgrass (Panicum virgatum L.) is one such species with potential to be used as an alternative feedstock, but establishment is slow and requires long term commitment of land to reach maximum productivity. Switchgrass can be established while producing a corn crop using 2-4-D and atrazine herbicide and seeding switchgrass prior to corn planting, reducing the risk of producing switchgrass as a crop. Relative performance of both corn and switchgrass in the landscape can vary and can influence productivity. An experiment was conducted which examined performance of corn during establishment of `Cave-in-Rock' and `Kanlow' switchgrass, stand frequency in the following year, subsequent yield, and composition of harvested switchgrass biomass across a toposequence of landscape positions. Seeding switchgrass reduced yields from 11.6 Mg*ha-1 to 9.6 Mg*ha-1 and from 10.8 Mg*ha-1 to 8.3 Mg*ha-1, for grain and stover, respectively. Establishment stand frequencies were adequate in all landscape positions and frequencies ranging from 39 to 82 percent. Yield and cellulose concentration of subsequent year switchgrass biomass was greater for `Kanlow'. Nitrogen concentration was lower in `Kanlow', but overall N removal was greater due to higher yield. Landscape position effect was demonstrated in the floodplain only, with floodplain position higher in total dry matter yield, ash content, N removal, and cellulose. Floodplain position biomass was lower in hemicellulose and total C. Switchgrass can be established in all landscape position when seeded prior to corn planting, subsequent composition of switchgrass varied by variety and landscape position. More years of data are needed to confirm these biomass quality differences between variety and landscape position.