PS 63-2 - Reduction in daily soil temperature range increase microbial community dynamics in a dryland cotton production system in West Texas

Friday, August 11, 2017
Exhibit Hall, Oregon Convention Center
Diana L. Vargas-Gutierrez1, V. Acosta-Martinez2, Bobbie McMichael1 and John Zak1, (1)Biological Sciences, Texas Tech University, Lubbock, TX, (2)Cropping Systems Research Laboratory, USDA-ARS, Lubbock, TX

Sustainability of agriculture in the Southern High Plains of West Texas faces challenges due to the variability that climate change is imposing on soil health, microbial dynamics, water use and plant productivity. Soil temperature is crucial for plant growth, and the ability of microorganism to carry out fundamental process. One component of soil temperature that have been shown to have a large impact on microbial activity in arid and semi-arid environments is the variation in Daily Temperature range (DTRsoil). Thus, it is imperative to understand how temperature variability at the daily scale influences microbial communities and their roles in nutrient cycling, and carbon storage. We evaluated the impacts of modifying DTRsoil on soil microbial processes in dryland cotton system in West Texas. For 2014-2015 growing season, 3 treatments were established: Control, reduced DTRsoil using erosion blankets (shade), and reduced DTRsoil using sorghum residue (stubble) to modify DTRsoil. Six replicates plots (3 x 4 m) with 4 rows in each treatment. Soil samples were collected monthly from each set of plots to evaluate edaphic parameters, nutrients levels (extractable NH4 +-N and NO3--N), and microbial structure and functional parameters. 


The stubble and shade reduced the DTRsoil by 6 °C on average at the soil surface and 2 °C at 15 cm during the hottest months. Overall, microbial biomass carbon was significantly greater (60%) in the shade plots and 62 % in the stubble plots with respect to control plots in 2014. Microbial biomass carbon did not differ significantly among the treatments in 2015. Arbuscular Mycorrhizal fungi FAME markers were more associated with stubble and shade plots than with the controls. Levels of extractable NO3--N were significantly higher in control plots in comparison with shade and stubble plots in both years and levels of extractable NH4+-N were significantly higher in control in comparison with shade and stubble, but did not show any differences between the treatments in 2015. The reduction in DTRsoil in these semi-arid systems positively affected the dynamics of microbial communities and their contributions to soil productivity. Understanding the role of DTRsoil will help cotton producers mitigate climate variability impacts and improve soil health leading to sustainable production in dryland cotton production system.