Doctoral Dissertations
Date of Award
5-2025
Degree Type
Dissertation
Degree Name
Doctor of Philosophy
Major
Natural Resources
Major Professor
Patrick D Keyser
Committee Members
Sindhu Jagadamma, Dennis R. West, Ken Coffey
Abstract
Summer cattle production for cow-calf pairs on tall fescue (TF) is impacted by fescue toxicosis and the semi dormancy of TF. Native warm-season grasses (NWSG) could be a viable forage option to fill the forage gap during the summer, lowering the amount of time that cow-calf pairs spend on toxic TF and improve soil health. However, little data is available on how NWSG affect the productivity of cow-calf operations on a farm scale. Therefore, we implemented an experiment at three sites, Booneville, AR, Linneus, MO and Louisville, TN, with cow-calf pairs (mature cows ≥3 years old, spring calving). We evaluated two forage systems that mix either a NWSG [big bluestem/indiangrass (BBIG) blend, eastern gamagrass (EG), or switchgrass (SG)] with TF, and compared them to a system that relies on TF only. Cattle (n = 12 pairs per experimental unit) were weighed yearly before initial grazing and again after final removal. Forage samples (n = 15) were collected at the beginning of grazing and once every twenty-eight days during the grazing season, and finally, at the conclusion of grazing. Harvested forages were tested for forage nutritive content (CP, NDF, ADF) using NIRS. Hay produced per system was documented. Input costs associated with each system were documented to compare the net returns to each system and per cow. At initiation and conclusion of the study, samples were taken for soil organic carbon (SOC) concentration, total nitrogen (N), bulk density (BD), wet aggregate stability (WAS), pH and Mehlich-3 nutrient concentrations. Mixed results indicate that incorporating NWSG in a program with TF may be of economic value to cow-calf production systems and could be a useful strategy to help lessen fescue toxicosis effects. In TN, there was indication that non-native, warm-season volunteer grasses within TF could be of help in lessening fescue toxicosis, while providing beneficial forage. Further research is needed to determine what factors will increase carbon stocks, C:N ratios, WAS and BD within NWSG and non-native soils under grazing.
Recommended Citation
Berry, Megan E., "Improving Eastern Grasslands Through Native Warm-Season Grasses. " PhD diss., University of Tennessee, 2025.
https://trace.tennessee.edu/utk_graddiss/12309