Tuesday, November 3, 2009
Convention Center, Exhibit Hall BC, Second Floor
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, residue return, and residue quality. Removal of nutrients and carbon via complete residue removal can decrease soil organic carbon (SOC), nutrient cycling, and productivity. The goal of this research was to optimize the efficiency of crop inputs and soil and environmental quality in biomass sorghum systems. The two-year field study took place in College Station and Weslaco, Texas, with direct observation of several management practices for high biomass sorghum. The study utilized a complete factorial design with four replications of the following factors: Rotation: continuous biomass sorghum vs. rotated every other year with corn; Stover Return: 0, 25, 50% of the sorghum biomass and all corn stover; and N Rate: 0 vs. non-limiting N. The biomass sorghum used in all studies was a high-yield photoperiod-sensitive hybrid. All other inputs and practices were those commonly used in the respective areas. Sorghum was harvested each season for yield and quality parameters including total concentrations of C, N, P, K, and other selected nutrients. 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, and soil microbial activity. Total yields, C, N, P, and K uptake in sorghum were significantly increased by N fertilization while 25% residue return significantly increased sorghum yield and N uptake at College Station the first year. At Weslaco, C and N uptake were increased by N fertilization (Fisher’s LSD <0.05). Second year yield and uptake data as well as changes in soil quality parameters will also be presented.