The Potential of Maize and Sorghum Biomass Grown On Marginal Sites.

The Renewable Fuels Standard mandates that 36 billion gallons of ethanol be produced annually by 2022. It is estimated that 15-20 billion gallons of ethanol will need to come from lignocellulose to achieve this mandate. To meet these demands marginal lands will undoubtedly have a larger role for bioenergy crop production; however, it is not well known how the proposed annual and perennial biomass crops will perform on these soils. Our objectives were to assess the agronomic performance of annual species: maize (Zea mays), photoperiod-sensitive sorghum x sudan hybrid (PPS) (Sorghum bicolor L. Moench), sweet sorghum (SS) (Sorghum bicolor L. Moench), and dual-purpose sorghum (DPS) (Sorghum bicolor L. Moench), and the perennial species: Miscanthus, lowland switchgrass, and a big bluestem/indiangrass prairie. Three sites were selected throughout Indiana that had several suboptimal characteristics for production including parent material, texture, drainage, and slope. Results for the annual crops are reported here. The crops were planted in four rows and fertilized with 0, 50, 100, 150, or 200 kg ha^-1 N. The center two rows were harvested and the whole plant used for chemical analysis. The species x location interaction was significant for yield. Maize had a total biomass yield ranging from 548 to 10,768 kg ha^-1, while SS had the highest biomass ranging from 8,750 to 16,753 kg ha^-1. The biomass cellulose concentration was also different across locations and species with maize having the lowest cellulose concentration (160 to 280 g kg^-1), while PPS had the highest (250 to 350 g kg^-1). Predicted conversion of both cellulose and hemicellulose into ethanol differed significantly with species and location with maize ethanol production potential ranging from 102 to 1228 L ha^-1, while PPS had the greatest predicted ethanol production (1368 to 2333 L ha^-1). Our initial results suggest sorghum has the potential to produce more ethanol on these marginal soils when compared to maize.