Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 8/28/2013
Publication Date: 8/28/2013
Citation: Cotton, J.E., Acosta Martinez, V., Burow, G.B., Moore-Kucera, J. 2013. Early changes due to sorghum biofuel cropping systems in soil microbial communities and metabolic functioning. 2013 Sorghum Improvement Conference of North America, August 28-30, 2013, Lubbock, Texas. p.21-22. Interpretive Summary:
Technical Abstract: Evaluation of biofuel production cropping systems should address not only energy yields but also the impacts on soil attributes are important for long-term sustainability. In this study, forage sorghum (Sorghum bicolor L. Moench) cropping systems were initiated on a low organic matter soil (< 0.9%) with a history of intensively-tilled low-input cotton production in the semiarid Southern High Plains of the U.S. Sorghum cropping systems were evaluated in a split-plot design with sorghum cultivar as the main plot and the combination of irrigation level (non-irrigated and deficit irrigated) and aboveground biomass removal rate (50% and 100%) as the split plot. The sorghum cultivars used varied in yield potential and lignin content, which are important features for feedstock-producing crops. Within one year, the transition from long-term cotton cropping systems to sorghum biofuel cropping systems resulted in increased soil microbial biomass C (16%) and N (17%) and shifts in the microbial community composition as indicated by differences in fatty acid methyl ester (FAME) profiles. Additionally, enzyme activities targeting C, N, P and S cycles increased 15-75% (depending on enzyme) after two growing seasons. Increased enzyme activities (16-19%) and differences in FAME profiles were seen due to irrigation regardless of aboveground biomass removal rate, which may be due to an increase in belowground biomass production even with limited irrigation. Biomass removal rate and the cultivar type had little effect on the soil microbial properties during the time frame of this study. Early results from this study suggest improvements in soil quality and the sustainability of sorghum biofuel cropping for low organic matter agricultural soils.