Winter Biomass Yield, Year-Round Elemental Concentrations of 'Kanlow' Switchgrass, and Associated Soil Nutrients in a Zero Input Environment

Abstract

Switchgrass (Panicum virgatum L.) is a warm-season perennial species native to North America. It was selected by the U.S. Department of Energy (DOE) as the model herbaceous species for the development as a cellulosic feedstock crop for biofuels production. Maximum biomass yields in switchgrass can be harvested with one-cut system by mid-September. However, information is limited on winter biomass yield, elemental composition of standing cured biomass, and associated soil nutrient status. Therefore, the objectives of this study were to evaluate changes in winter biomass yield, year-round elemental composition of Kanlow switchgrass, and associated year-round soil nutrient dynamics in a zero input environment. An unfertilized Kanlow switchgrass planting established in 1998 was used in the study. The experimental design was a split plot randomized complete block design with 6 replications. The experimental treatment was monthly harvest from November to March in winter and year-round monthly sampling of biomass and soil for chemical analyses. The variable year was sub-plot within the main plot month. Each replication was on a large plot of 200 m2. The 2-yr mean dry matter yield of winter harvests was 5.13 t/ha, ranging from 3.88 t/ha in 2007-2008 to 6.38 t/ha in 2008-2009. Biomass yield decreased as winter progressed, statistically significant in first winter but not in the second winter. Concentrations of biomass elements and soil nutrients changed with various degrees over the two years. Biomass quality was not affected by harvesting `Kanlow' switchgrass from November to March as nutrient, ash, and cell wall components were not affected.