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 emissions 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-Nebraska-Kansas (MINK) region of the US of converting some agricultural land to the production of switchgrass (Panicum virgatum L.), a perennial warm season grass, as a biomass energy crop. The erosion productivity impact calculator (EPIC) crop growth model simulated production of corn (Zen mays L.), sorghum (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 climate model-based scenario of possible climate change. Daily climate records from 1983 to 1993 served as baseline and the NCAR-RegCM2 model (RegCM hereafter) nested within the CSIRO general circulation model (GCM) provided the climate change scenario. Crop production was simulated at two atmospheric CO2 concentrations ([CO2]) at 365 and 560 ppm to consider the CO2-fertilization effect. Simulated yields of the perennial switchgrass increased at all sites with a mean yield increase of 5.0 Mg ha(-1) under the RegCM climate change scenario. Switchgrass yields benefited from temperature increases of 3.0-8.0 degrees C, which extended the growing season and reduced the incidence 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-fertilization 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 temperatures of the CSIRO scenario. Precipitation increases resulted in greater runoff from the traditional crops but not from switchgrass due to the crop' s increased growth and longer growing season. Simulated soil erosion rates 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 winds at that time. (C) 2000 Elsevier Science B.V. All rights reserved.