Biomass Production Potential of Wheat, Corn, and Sorghum in Dryland Cropping Environments.

Establishing a baseline of crop and residue production is the first step in determining the sustainability of harvesting agricultural biomass for ethanol production in semi-arid regions. This study examines the potential for producing biomass (grain and stover) as a feedstock for bioenergy production in dryland cropping systems in Eastern Colorado.  An on-going dryland cropping system study was initiated in 1985 at three locations, giving a database of 69 site-years. Different rates of grain and residue production among crops, locations, and study years provide a wide range in residue return rates that can be used to establish a baseline for potential biomass production. This study evaluates biomass production for winter wheat (Triticum aestivum), corn (Zea mays), and sorghum (Sorghum bicolor) under non-irrigated, no-till conditions. The three field locations in Colorado (Sterling, Stratton, and Walsh) provide a wide range in precipitation and weather variables across an evapotranspiration gradient. All sites have long-term precipitation averages of 400-450 mm, but increase in potential evapotranspiration from north to south. Grain, stover, and total biomass were measured annually for each site and analyzed within and across years, and within and across soil type and potential evapotranspiration gradients. Biomass production in semi-arid environments is heavily linked to growing-season precipitation rates. Hence, yields from normal to average rainfall periods were compared to production under below average rainfall periods over the 23 years of data. The implications of crop residue removal, as well as recommended removal rates will be reported.