Simulating the Yield Variation of Switchgrass (Panicum virgatum) Due to Climate and Soil Variability In the Southeastern USA.

Switchgrass (Panicum virgatum) is a perennial warm-season grass that is native to North America and is characterized by high biomass productivity, and nutrient and water use efficiency. The species has been evaluated as a potential crop for cellulosic biofuel production, with generally favorable results. However, growth and yield of switchgrass vary substantially due to weather, soil and other environmental factors. In this study we evaluated the performance of the Agricultural Land Management Alternative with Numerical Assessment Criteria (ALMANAC)-model to simulate growth and yield of switchgrass as a function of weather, soil and crop management factors that represented the southeastern USA. First, we compared the model simulations with observed switchgrass (cv Alamo) data collected in field experiments from 5 locations over 6 years in Alabama, USA. Subsequently, we applied the model to determine switchgrass yield potential for climate and soil conditions that represented 13 counties in the Tennessee River valley region of northern Alabama and Georgia, USA. In addition, the simulated conditions included weather data from 3 time periods, the 1950s, 1960s and the 1980s, to account for the climate variability during the 20^th century. Based on the simulations and previously published field surveys of farmers’ interest in switchgrass production, we estimated the total switchgrass production potential in this region under different climate and land use scenarios. The results showed a significant yield variation due to spatial and temporal weather and climate variability and spatial soil variability within the 13 counties. Notably, yields of switchgrass were significantly higher for weather data representing 1950s and 1980s than for weather data representing the 1960s. These results can be used in planning of future energy systems that are based on switchgrass as a biofuel feedstock.