Management Effect On Yield, Nutrient Uptake, and Soil Quality In Bioenergy Sorghum Production.

Soil is the fundamental resource in agricultural systems and maintaining soil quality is key to ensuring sustainable production. Productivity and soil quality may be affected by cropping sequence complexity, fertilization, and residue removal. The goal of this research was to optimize the efficiency of crop management and soil and environmental quality in high biomass (bioenergy) sorghum systems. The two-year field study, utilizing fourteen management systems, took place in College Station Texas. The study utilized a complete factorial design with four replications of the following factors: Rotation: continuous biomass sorghum vs. biannual rotation with corn; Biomass Return: 0, 25, 50% of the sorghum biomass and all corn stover; and N Rate: 0 vs. non-limiting N. The bioenergy sorghum used in all studies was a high-yield photoperiod-sensitive hybrid. All other inputs and practices were those commonly used. Sorghum was harvested for yield and total concentrations of C, N, P, K, and other selected nutrients were determined. Soil samples were taken at the beginning of the study, with additional samples being collected before the second growing season. Samples were analyzed for soil quality parameters including total organic and inorganic carbon and nitrogen, residual nitrate and other available nutrients. Rotation, fertilization, and residue return affected yields, plant growth, and soil quality (p <0.05). The first two years of study showed that biomass sorghum yielded three times more biomass than corn and sequestered more soil organic carbon (C) and total nitrogen (N) to a depth of 90 centimeters. However, continuous sorghum production reduced sorghum yields and the availability of soil P and K from 30 to 90 centimeters of depth compared to biannually rotated corn-sorghum systems. Near the soil surface, 50% biomass return showed significantly higher C, total N, P, and K than 0% or 25% return.