Nutrient and Carbohydrate Partitioning in Sorghum Stover

Abstract

AbstractAlthough petroleum fuels have been abundant during the past decade, alternative energy sources are needed for the long term. Sorghum [Sorghum bicolor (L.) Moench] stover has been demonstrated to be a potential biomass energy source. Complete above‐ground crop removal, however, can result in soil degradation. Differential dry matter, nutrient, and carbohydrate partitioning by sorghum cultivars may allow management strategies that return certain stover parts to the field while removing other portions for alternative uses, such as energy production. A field study was conducted to determine N, P, K, nonstructural carbohydrate, cellulose, hemicellulose, and lignin distributions in stover of three diverse sorghum cultivars of differing harvest indices. Determinations were based on total vegetative biomass; total blades; total stalks; and upper, middle, and lower blades and stalks. Concentrations of N and P were higher in blades than stalks and generally declined from upper to lower stover parts. Large carbohydrate and lignin concentration differences were observed on the basis of cultivar and stover part. Greater nutrient partitioning to the upper third of the intermediate‐ and forage‐type sorghum stovers was observed as compared to the conventional grain cultivar. Stover carbohydrates for all cultivars were mainly contained in the lower two‐thirds of the stalk fraction. A system was proposed for returning upper stover portions to soil, while removing remaining portions for alternative uses.