Soil nutrient removal by four potential bioenergy crops: Zea mays, Panicum virgatum, Miscanthus × giganteus, and prairie

Abstract

Replacing annual row crops with perennial grasses for bioenergy represents a landscape-level change in species composition, with the potential to impact annual soil nutrient removal on a regional scale. In this study we measured the concentration of ten essential nutrients in harvested material from three potential perennial bioenergy crops: Panicum virgatum L., Miscanthus×giganteus, and a reestablished prairie to determine annual soil nutrient removals. We compared perennial bioenergy crops to nutrient removals by annual cropping systems of Zea mays L. (maize) and Glycine max L. (soybean) in Illinois. Crops were grown under management practices typical for the Midwest, US. In addition, we examined geographic variation in nutrient removal of M.×giganteus at four US locations. Total removal of N, P, K, Ca, Mg, S, Fe, Mn, Na, and Zn was significantly greater in maize than in any of the perennials. Removal of N, P, and K in M.×giganteus was 3.7, 1.8, and 1.8% of the removal in maize, and 49.0, 17.4, and 31.9% of the removal in soybean respectively. At sites in Illinois, Kentucky, Nebraska, and New Jersey we found differences in N and K removal by M.×giganteus that corresponded with differences in biomass. There was no effect of fertilization on M.×giganteus biomass, but removal of N, S, and Mg increased and P removal decreased with increasing rates of urea fertilization. Cultivation of M.×giganteus and switchgrass on land formerly used for row crops may reduce the need for nutrient additions and potential losses of nutrients to groundwater and the atmosphere.