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Title: THE INFLUENCE OF GRAZING ON MICROBIAL ACTIVITY IN A NORTHERN MIXED-GRASS PRAIRIE

Author
item INGRAM, LACHLAN - UNIVERSITY OF WYOMING
item Schuman, Gerald
item STAHL, PETER - UNIVERSITY OF WYOMING
item WELKER, JEFF - COLORADO STATE UNIVERSITY
item VANCE, GEORGE - UNIVERSITY OF WYOMING
item GANJEGUNTE, GRISHA - UNIVERSITY OF WYOMING

Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 8/25/2004
Publication Date: 10/31/2004
Citation: Ingram, L.J., Schuman, G.E., Stahl, P.D., Welker, J.E., Vance, G.F., Ganjegunte, G.K. 2004. The influence of grazing on microbial activity in a northern mixed-grass prairie. Agronomy Abstracts 4164.

Interpretive Summary:

Technical Abstract: Grazing management has been shown to directly influence soil organic carbon (SOC) and nitrogen (N) in rangelands. While this can be due to changes in plant community and/or the influence of grazing, changes in microbial community may also lead to differences. We sampled a previously established study in which two replicates of three treatments; exclosure/non-grazed (EX); continuous light (CL); and continuous heavy (CH) grazing had been imposed on a northern mixed-grass community for 20 years. Soils were sampled at 0-5, 5-15, 15-30, and 30-60 cm depths, and short-term (3 days; 3d-MR) and long-term (21 days; 21d-MR) microbial respiration, microbial biomass C (MBC) and potential N-mineralization were measured in the laboratory. The 3d-MR, 21d-MR, and N-mineralization were distinctly different in the order of CL>EX>>CH. There was also 8% greater nitrate in the CL treatment compared to the EX and CH treatments suggesting that possible differences in the nitrify populations between these treatments. Along similar lines, MBC was higher in the CL than the EX treatment and both were much greater compared to the CH treatment. This research suggests that microbial communities could, over time, have a considerable impact on soil C by influencing both the N availability for plant growth as well as turnover rates of soil organic C.