Potential production and environmental effects of switchgrass and traditional crops under current and greenhouse-altered climate in the central United States: a simulation study

If, as many climate change analysts' speculate, industrial and other emissi ons of CO2 can be offset by substitution of biofuels, large areas of land, including agricultural land, may be converted to the production of biomass feedstocks, This paper explores the feasibility for the Missouri-Iowa-Nebra ska-Kansas (MINK) region of the US of converting some agricultural land to the production of switchgrass (Panicum virgatum L.), a perennial warm seaso n grass, as a biomass energy crop. The erosion productivity impact calculat or (EPIC) crop growth model simulated production of corn (Zen mays L.), sor ghum (Sorghum bicolor (L,) Moench), soybean (Glycine max L,), winter wheat (Triticum aestivum L.) and switchgrass at 302 sites within the MINK region. The analysis is done for both current climatic conditions and a regional c limate model-based scenario of possible climate change. Daily climate recor ds from 1983 to 1993 served as baseline and the NCAR-RegCM2 model (RegCM he reafter) nested within the CSIRO general circulation model (GCM) provided t he climate change scenario. Crop production was simulated at two atmospheri c CO2 concentrations ([CO2]) at 365 and 560 ppm to consider the CO2-fertili zation effect. Simulated yields of the perennial switchgrass increased at a ll sites with a mean yield increase of 5.0 Mg ha(-1) under the RegCM climat e change scenario. Switchgrass yields benefited from temperature increases of 3.0-8.0 degrees C, which extended the growing season and reduced the inc idence of cold stress. Conversely, the higher temperatures under the RegCM scenario decreased yields of corn, soybean, sorghum and winter wheat due to increased heat stress and a speeding of crop maturity. With no CO2-fertili zation effect, EPIC simulated maximum decreases from baseline of 1.5 Mg ha( -1) for corn, 1.0 Mg ha(-1) for sorghum, 0.8 Mg ha(-1) for soybean and 0.5 Mg ha(-1) for winter wheat. Simulated yields increased for all crops under the RegCM scenario with CO2 set to 560 ppm. Yields increased above baseline for 34% of the soybean and 37% of the winter wheat farms under RegCM/[CO2] = 560 ppm scenario, Water use increased for all crops under the higher tem peratures of the CSIRO scenario. Precipitation increases resulted in greate r runoff from the traditional crops but not from switchgrass due to the cro p' s increased growth and longer growing season. Simulated soil erosion rat es tinder switchgrass and wheat cultivationwere less severe than under corn management. However, simulated erosion under switchgrass was considerable in eastern Iowa during the period of crop establishment because of strong w inds at that time. (C) 2000 Elsevier Science B.V. All rights reserved.