Influence of Forage Sorghum Systems Under Different Tillage Practices on Microbial Biomass and Soil C/N Pools.

Sorghum has become a popular annual forage and silage crop in the Southern Great Plains. Most sorghum hybrids require higher nitrogen fertilization for sustainable biomass production and subsequent removal for grazing or hay. Higher nitrogen application and monoculture sorghum systems can negatively influence the soil health over time. This study was conducted to evaluate the effects of crop diversification and tillage on forage sorghum production in the Southern Great Plains. Specific goals of this project are to evaluate the winter crop rotations with sorghum and their influence on soil microbial communities and soil carbon and nitrogen pools, under different tillage and grazing practices. Field experimental plots with forage sorghum were under till and no-till, and winter crop rotations with either oats or grass peas. Soil core samples (0-60 cm depth) at several time points were obtained for assessing soil microbial biomass, diversity and abundance. The soil health was assessed by comparing the water extractable organic carbon and nitrogen pools and using phospholipid fatty acid (PLFA) analysis to estimate microbial biomass.