Management of Perennial Warm-Season Bioenergy Grasses. I. Biomass Harvested, Nutrient Removal, and Persistence Responses of Elephantgrass and Energycane to Harvest Frequency and Timing

Abstract

Harvest management practices affect productivity and persistence of grasses grown for bioenergy, but data are limited that describe their effects on the tall-growing grasses adapted to the USA Gulf Coast region. The objective was to determine harvest frequency and timing effects on biomass yield, nutrient removal, and persistence of three perennial bioenergy grasses in the southeastern USA. The experiment was conducted from 2010 through 2012. Harvest management treatments were two harvests per year (2X; July and November), one harvest per year in early November (fall), and one harvest per year after first freeze (winter). Elephantgrass (Pennisetum purpureum Schum.) cv. Merkeron and breeding line UF1 and energycane (Saccharum spp.) cv. L 79-1002 were compared. Three-year average biomass harvested was greatest for UF1 followed by Merkeron and L 79-1002 (27.8, 24.6, and 21.1 Mg ha−1year−1, respectively). Biomass harvested was not affected by harvest management in 2010 and 2011, but in 2012, the 2X treatment yielded 47 % less than winter. Biomass dry matter (DM) concentration for single harvest treatments was greater than 2X (34 vs. 25 %), but the 2X treatment removed two times more N and P in harvested biomass than fall or winter. For these grasses, fall and winter single harvest treatments were superior to 2X due to greater third year biomass yield, less nutrient removal, and harvested biomass had a greater DM concentration that may be advantageous for postharvest transport and processing.