YIELD OF SWITCHGRASS ON RECLAIMED SURFACE MINES 1

Abstract

Growing crops for biofuel production on agricultural land has caused conflict between choosing biomass crops for fuel instead of food for a growing world population. This has increased interest in growing biofuel feedstocks on marginal lands. Switchgrass (Panicum virgatum L.), a warm-season perennial grass, has been shown to be a viable bioenergy crop because it produces high yields on marginal lands under low water and nutrient conditions. From previous studies, switchgrass yields on marginal croplands varied from 5,000 to 10,000 kg ha -1 . West Virginia contains immense acreages of reclaimed surface mine lands and could offer enough area for the production of switchgrass as a feedstock for a biofuel industry. For reclaimed lands, yield targets of 5,000 kg ha -1 were established by researchers as the yield necessary for economic feasibility for landowners. This study was established in 2008 to determine switchgrass yields of different cultivars on mine sites in West Virginia. Three varieties of switchgrass were tested on two mine sites, Hampshire Hill and Hobet. The Hampshire Hill mine site, which was reclaimed in the early 1990's using top soil and treated municipal sludge, consistently had the highest yield of the two sites with a fifth year yield of 9,066 kg ha -1 averaged across varieties. Cave-in-Rock variety produced 15,600 kg ha -1 of biomass which was more than the other two varieties, Shawnee and Carthage, at 8,600 and 3,000 kg ha -1 . The other mine site, Hobet, was prepared using crushed, unweathered sandstone in 2008. Yields of switchgrass were 890 kg ha -1 for the fifth year of production, with Cave-in-rock producing the most biomass at 1,275 kg ha -1 . The two sites had different physical soil characteristics. While both sites had low contents of % fines and high rock fragment contents (material >2mm in size) Hobet had significantly lower % fines than Hampshire Hill. The type and quality of soil and the variety of switchgrass selected for seeding should be considered when the goal is chiefly high yields of switchgrass for biofuel production.