Agronomic and environmental effects of forage-cutting schedule and nitrogen fertilization for bermudagrass (Cynodon Dactylon, L.)

Authors: Sohoulande, Clement; Ma, Liwang; QI, ZHIMING - McGill University - Canada; SZOGI, ARIEL - Retired ARS Employee; Stone, Kenneth; Harmel, Daren; Martin, Jerry; Birru, Girma; SIMA, MATTHEW - Princeton University

Submitted to: Agriculture, Ecosystems and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/29/2024
Publication Date: 10/3/2024
Citation: Sohoulande Djebou, D.C., Ma, L., Qi, Z., Szogi, A., Stone, K.C., Harmel, R.D., Martin, J.H., Birru, G.A., Sima, M. 2024. Agronomic and environmental effects of forage-cutting schedule and nitrogen fertilization for bermudagrass (Cynodon Dactylon, L.). Agriculture, Ecosystems and Environment. 378. Article 109318. https://doi.org/10.1016/j.agee.2024.109318.
DOI: https://doi.org/10.1016/j.agee.2024.109318

Interpretive Summary: Bermudagrass is widely used as a forage in ruminant diets across the United States (US) owing to its nutritional value and capacity to grow under various agroecological conditions. In the southeastern US, research recommends the bermudagrass cultivar Tifton 85 for forage production and monthly frequency for biomass-cutting. However, the existing information is inadequate for precise management of harvesting schedules to optimize forage quantity and quality. Moreover, the effect of the forage-cutting events and nitrogen fertilization rates is not well understood. In this study, experimental data of irrigated bermudagrass Tifton 85 forage production under three nitrogen fertilization rates, were used to calibrate a model for biomass weight and biomass nitrogen content. For each nitrogen fertilization rate, multi-year simulations of four cutting scenarios were used to investigate the effects of harvesting schedules and nitrogen fertilization rates on biomass weight, biomass nitrogen content, nitrogen use efficiency (NUE), and nitrogen leaching. Results show statistically significant effects of the cutting scenarios on biomass weight and biomass nitrogen content for both high and medium fertilization rates. The low nitrogen rate fertilization did not show any statistically significant effect except for the biomass weight. NUE values were higher with both medium and low nitrogen fertilization rates compared to the high nitrogen fertilization which showed a relatively high nitrogen leaching. The outcomes of this study can be used to inform bermudagrass cutting and fertilization options to achieve forage yield goals with an understanding of the potential environmental consequence of nitrogen leaching.

Technical Abstract: Bermudagrass (Cynodon dactylon, L.) is widely used as a forage in ruminant diets owing to its nutritional value and capacity to grow under various agroecological conditions. In the southeastern United States, research recommends the bermudagrass cultivar Tifton 85 for forage production and a monthly frequency for biomass-cutting. However, there is not sufficient guidance for adequate harvesting schedules to optimize the forage quantity and quality. Moreover, the interplay between the forage-cutting events and nitrogen (N) fertilization rates is not well understood. In this study, experimental data of bermudagrass Tifton 85 forage production under three N fertilization rates (i.e., high = 504 kg N/ha, medium = 336 kg N/ha, and low = 168 kg N/ha), were used to calibrate and validate Root Zone Water Quality Model 2 (RZWQM2) for biomass weight and biomass N content. For each N fertilization rate, multi-year simulations of four cutting scenarios were used to investigate the joint effects of harvesting schedules and N fertilization rates on biomass weight, biomass N content, N use efficiency (NUE), and N leaching. Results show statistically significant effects of the cutting scenarios on biomass weight and biomass N content for both high and medium N fertilization rates. The low N fertilization did not show any statistically significant effect except for the biomass weight. NUE values were higher with both medium and low N fertilization rates compared to the high N fertilization which showed a relatively high N leaching. The outcomes of this study can be used to inform bermudagrass cutting and fertilization options to achieve forage yield goals with an understanding of the potential environmental consequence of N leaching.