Impact of Cover Crops and Tillage Management on the Cotton Rhizosphere.

Conservation tillage is a common management practice utilized in the hopes of reducing soil erosion and increasing soil carbon. Additionally, cover crops are frequently utilized to improve soil nutrient levels, and increase soil fertility. Evidence suggests that both management practices may lead to habitat improvement for soil microorganisms, in particular rhizospheric bacteria and arbuscular mycorrhizal fungi (AMF) communities. In turn, these communities may confer drought resistance for plants, and decrease fertilizer inputs. To gain a better understanding of how soil management practices influence plant-soil-microbial interactions, we conducted an experiment utilizing long-term (established in 1978) plots to compare the long-term effects of conventional and conservation tillage, as well as the inclusion of cover crops in more recent years. Plots are currently under a corn-cotton rotation allowing us to examine the effects of both crop type and soil management on microbial communities. Bacterial communities were “fingerprinted” and analyzed using terminal restriction fragment length polymorphism (T-RFLP), and extracellular soil enzymes were measured using fluorescent substrates in a microtiter format. By correlating microbial communities with plant nutrients and soil properties, findings from this study will further our understanding of how soil management practices impact plant-microbe relations and plant productivity. Ultimately, this research can aid in the development of best management practices that reduce fertilizer and water input.