N cycling summary 2020-2022 of annually burned bison, cattle and ungrazed experimental watersheds on upland tallgrass prairie soils at the Konza Prairie Biological Station

Nitrogen (N) is a necessary element of soil fertility and a limiting nutrient in tallgrass prairie but grazers like bison and cattle can also recycle N. Bison and cattle impact the nitrogen (N) cycle by digesting forage that is consumed, and recycled back to the soil in a more available forms stimulating soil microbial N cycling activities. Yet we do not know how both grazers comparatively affect N cycling in tallgrass prairie. Thus, we investigated if bison cattle had similar impacts on N cycling in annually burned tallgrass prairie relative to ungrazed conditions over a 3-year period (2020-2022) at the Konza Prairie Biological Station. We took soil samples to investigate soil data: pH, soil water content, mineralized N, nitrification potential, denitrification potential and extracellular enzyme assays on upland soils of the Florence-Benfield complex soil map during the summer growing season from 2020 to 2022 on bison, cattle and ungrazed experimental watersheds at the Konza Prairie Biological Station. Soil sampling was undertaken once late in each summer growing season from 2020-2022. These years spanned a range of above-average rainfall (2020) to well below average (2021) and slightly below average (2022). We sampled along four 10-m transects, parallel to long-term plant sampling transects in each experimental watershed, in two bison grazed (N1A and N1B), two cattle grazed (C1A and C1B), and two ungrazed (1D and SpB) watersheds, all of which are burned annually.