IMPACT OF LAND USE ON MICROBIAL COMMUNITIES IN THE GREAT BEND PRAIRIE AQUIFER

The High Plains aquifer is a vital source of irrigation and drinking water in the central United States. Therefore, it is important to understand how changes in aquifer geochemistry and microbial communities affect the health of the aquifer. Recent analysis of the Great Bend Prairie aquifer, a portion of the High Plains aquifer in south-central Kansas, indicates nitrate levels are increasing, particularly in shallow zones of the aquifer. Based on the analysis, nitrate-nitrogen levels increased 10.2 and 3.0 mg/L on average in the shallow and deep portions of the aquifer over the past 40 years. Oxygen and nitrogen isotopic composition of the nitrate falls primarily in the range associated with nitrification of ammonium fertilizer, indicating an agricultural source for the nitrate. (Richard, 2016).

Our current research considers the role of land use on aquifer microbial communities in the Great Bend Prairie aquifer. We hypothesized that land use significantly impacts the composition of the shallow aquifer microbial community and that the composition of the groundwater microbiome will be related to the composition of the soil microbiome. To test our hypotheses, we collected 112 soil samples from pasture and row crop sites in the field area. We will compare the microbial communities in the soil samples to the microbial community in aquifer microbe samples collected previously. In addition, we measured environmental parameters such as NO₃-N and NH₄-N, pH, and soil organic matter (SOM) and dissolved organic carbon (DOC) in the soil and shallow aquifer at each sampling site. To compare community composition between samples and environmental parameters, we will perform a beta diversity test. We expect to find that land use, the soil microbiome, and the aquifer microbiome are intricately connected.