Long-Term Effects of Rainfall Manipulation on the Soil Microbial Community of a Native Tallgrass Prairie.

Microorganisms play a vital role in maintaining soil health. An increase in precipitation variability will cause changes in soil moisture and impact the overall function of microbial communities and ultimately terrestrial ecosystems. Variability in seasonal and annual precipitation are a natural component of tallgrass prairie. Though soil microbes have developed mechanisms to adapt to environmental changes, the fluctuations in soil water potential can have a significant effect on the soil microbial community composition and its overall function. The goal of this study was to better understand the relationship between long term precipitation changes and soil microbial community composition and function. Soil samples were collected from the Konza Prairie Long-Term (20 years) Irrigation Transect located within Konza Prairie Biological Station in eastern Kansas, USA. The experimental design consists of two moisture regimes: irrigated to maintain soil moisture to minimize plant water stress and non-irrigated. Two replicate plots were sampled in both an upland and lowland portions of the field. Soil samples were taken in May, June, August, and October of 2016 and 2017. Phospholipid fatty acid analysis was conducted to compare differences within the microbial community composition and microbial biomass. We also measured inorganic N, total C and total N to assess soil quality. In 2016, precipitation reduced the need for irrigation. However, the long-term effect of irrigation reduced microbial biomass in the lowland position. Changes in the composition of the microbial community as a result of irrigation.