Understanding the agronomic impacts of defoliation strategies in “Bulldog 805” alfalfa + “Tifton 85” bermudagrass mixed stands

Authors: BAXTER, LISA - University Of Georgia; BURT, JUSTIN - University Of Georgia; MULLENIX, MARY - Auburn University; PAYNE, SYDNEY - University Of Georgia; REAGIN, KAYLYN - University Of Georgia; MASON, KATIE - University Of Tennessee; PREVATT, CHRIS - Non ARS Employee; TUCKER, JENNIFER - University Of Georgia

Submitted to: Grassland Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/7/2023
Publication Date: 10/31/2023
Citation: Baxter, L.L., Burt, J.C., Mullenix, M.K., Payne, S.L., Reagin, K.R., Mason, K.M., Prevatt, C.G., Tucker, J.J. 2023. Understanding the agronomic impacts of defoliation strategies in “Bulldog 805” alfalfa + “Tifton 85” bermudagrass mixed stands. Grassland Research. 2:251-259. https://doi.org/10.1002/glr2.12062.
DOI: https://doi.org/10.1002/glr2.12062

Interpretive Summary: Background The incorporation of legumes, specifically alfalfa (Medicago sativa L.), into bermudagrass (Cynodon spp.)-based pasture systems in the southeastern United States has increased in recent years as an alternative to synthetic nitrogen (N) fertilization. Methods A small plot evaluation was conducted in Shorter, Alabama, and Tifton, Georgia, USA, to evaluate the impact of harvest height (HH) and harvest frequency (HF) on agronomic characteristics of alfalfa+bermudagrass mixtures in southeastern United States. Results Results from both locations revealed that the longer the HF and the shorter the HH, the greater the alfalfa retention was in the stand (p'<'0.01). HH did not impact any of the reported nutritive value parameters, while longer HF resulted in lower total digestible nutrients, lower crude protein, higher acid detergent fiber, and lower 48'h in vitro dry matter digestibility (p'<'0.01). Both HH and HF impacted forage accumulation at both locations (p'<'0.01). HH resulted in different trends at each location, while longer frequencies generally increased forage accumulation. Conclusions This research confirmed recent findings from comparable evaluations in the southeastern United States, in that increasing HH and decreasing HF improved alfalfa retention while having a negligible effect on nutritive value or forage accumulation.

Technical Abstract: Background The incorporation of legumes, specifically alfalfa (Medicago sativa L.), into bermudagrass (Cynodon spp.)-based pasture systems in the southeastern United States has increased in recent years as an alternative to synthetic nitrogen (N) fertilization. Methods A small plot evaluation was conducted in Shorter, Alabama, and Tifton, Georgia, USA, to evaluate the impact of harvest height (HH) and harvest frequency (HF) on agronomic characteristics of alfalfa+bermudagrass mixtures in southeastern United States. Results Results from both locations revealed that the longer the HF and the shorter the HH, the greater the alfalfa retention was in the stand (p'<'0.01). HH did not impact any of the reported nutritive value parameters, while longer HF resulted in lower total digestible nutrients, lower crude protein, higher acid detergent fiber, and lower 48'h in vitro dry matter digestibility (p'<'0.01). Both HH and HF impacted forage accumulation at both locations (p'<'0.01). HH resulted in different trends at each location, while longer frequencies generally increased forage accumulation. Conclusions This research confirmed recent findings from comparable evaluations in the southeastern United States, in that increasing HH and decreasing HF improved alfalfa retention while having a negligible effect on nutritive value or forage accumulation.