Grazing intensity effects on sward responses of UF Riata Bahiagrass

Authors: SANTOS, ERICK - University Of Florida; DUBEUX, JOSE - University Of Florida; SOLLENBERGER, LYNN - University Of Florida; MACKOWIAK, CHERYL - University Of Florida; DILORENZO, NICOLAS - University Of Florida; RUIZ-MORENO, MARTIN - University Of Florida; Jaramillo, David; ZAGATO, LUANA - University Of Florida; GARCIA, CARLOS - University Of Florida; SIQUEIRA, MICHELLE - University Of Florida; VAN CLEEF, FLAVIA - University Of Florida; SILVA, GLEISE - University Of Alberta

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/28/2023
Publication Date: 8/4/2023
Citation: Santos, E., Dubeux, J., Sollenberger, L., Mackowiak, C., Dilorenzo, N., Ruiz-Moreno, M., Jaramillo, D.M., Zagato, L., Garcia, C., Siqueira, M., Van Cleef, F., Silva, G. 2023. Grazing intensity effects on sward responses of UF Riata Bahiagrass. Crop Science. 63(5):3122-3135. https://doi.org/10.1002/csc2.21069.
DOI: https://doi.org/10.1002/csc2.21069

Interpretive Summary: Forage quantity and quality, as well as sward persistence, are greatly affected by grazing intensity. Bahiagrass (Paspalum notatum Flüggé) is a rhizomatous perennial warm-season grass widely grown in the southern U.S.A. ‘UF Riata’ bahiagrass is a cultivar developed to be less sensitive to daylight variation and there are few studies evaluating above and belowground responses of UF Riata across a variety of grazing intensities. In this study, we looked at how bahiagrass pastures are affected when managed at different grazing intensities by imposing three different post-grazing residual herbage mass treatments. Our results showed that herbage growth rates and forage nutritive value were not affected by grazing intensities. Increasing grazing intensities decreased the overall root-rhizome biomass, indicating potential stress for overgrazed pastures. Considering both forage nutritive value and stand persistence, moderate grazing intensities are recommended.

Technical Abstract: Forage quantity and quality, as well as sward persistence, are greatly affected by grazing intensity. Bahiagrass (Paspalum notatum Flüggé) is a rhizomatous perennial warm-season grass widely grown in the southern U.S.A. ‘UF Riata’ bahiagrass is a cultivar developed to be less sensitive to daylight variation and there are few studies evaluating above and belowground responses of UF Riata across a variety of grazing intensities. This 3-yr study investigated how sward responses of bahiagrass are affected by different grazing intensities. Treatments consisted of three post-grazing residual herbage mass (HM) imposed by mob stocking every 14 d to reach the targets of 500 (overgrazing, OG), 1500 (moderate grazing, MG), or 2500 (undergrazing, UG) kg DM ha-1. Herbage accumulation (HA) rate was not affected by treatment. Crude protein (CP) and in vitro digestible organic matter (IVDOM) concentrations were similar among treatments within same harvest date. There was a linear effect of grazing intensity on root-rhizome biomass and soil cover, where both decreased linearly (P < 0.05) from 12940 to 9230 kg OM ha-1, and 97 to 93%, in UG to OG, respectively. There was a trend on appearance of spontaneous grasses in OG swards (P = 0.06), where at the end of the grazing season, these grasses comprised 34 and 17% of the herbage in OG and UG swards. Across treatments, proportion of other weeds increased from 2 to 22%, from the first to the last year. When considering both sward persistence and forage nutritive value, the use of moderate grazing intensity is recommended.