Monday, November 13, 2006

Essential Agronomic Practices for Managing Switchgrass for Bioenergy.

Robert Mitchell, "USDA-ARS, 362 Plant Science", "Box 830937, Univ. of Nebraska", "Box 830937, Univ. of Nebraska", Lincoln, NE 68583-0937, United States of America, Kenneth Vogel, "USDA-ARS, 344 Keim Hall", "PO Box 830937, Univ. Of NE", "PO Box 830937, Univ. Of NE", Lincoln, NE 68583-0937, United States of America, Gautam Sarath, USDA-ARS, Lincoln, NE 68583, and Marty Schmer, University of Nebraska - Lincoln, 3935 X St., 3935 X St., Lincoln, NE 68503, United States of America.

Our objective is to present the state of the art for establishing and managing switchgrass for Bioenergy.  The best and most productive switchgrass stands have been no-till seeded into soybean stubble.  It is crucial to select the proper cultivar for the specific plant adaptation region, purchase quality seed, properly calibrate the drill to dispense at least 225 pure live seed m-2, plant switchgrass at 10 mm deep in a firm seedbed, and apply pre-emergence herbicides like atrazine plus quinclorac to control grassy and broad leaf weeds.  It is important to monitor stands during the seeding year to determine if the stand is adequate to meet production goals. The primary fertilizer requirement of switchgrass is N, and adequate N is necessary to maintain stands.  Switchgrass N requirement depends on the yield potential of the site, the cultivar, and the management practices being used. In the Midwest, maximum first-cut yields are attained by harvesting switchgrass when panicles are fully emerged to the post-anthesis stage. Depending on the year, sufficient regrowth may occur to warrant a second harvest after a killing frost.  After harvest, poor storage conditions can result in storage losses as high as 24% in a single year.  Areas needing additional research include fertilizer requirements other than N, determining the stage of maturity at which dry matter production and biomass composition are optimized for biorefinery ethanol yield, and determining economical methods for storing switchgrass to reduce storage losses. Cultivars developed specifically for high potential ethanol yields are also needed. Based on more than 15 years of bioenergy research, switchgrass is an economically viable and sustainable source of bioenergy for the central USA east of 100o W. longitude, and provides an excellent source of cellulosic ethanol to reduce our dependence on fossil fuels.