Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/21/2018
Publication Date: 4/12/2018
Citation: Read, J.J., Lang, D., Adeli, A., Jenkins, J.N. 2018. Harvest management effects on "Tifton 44" Bermundagrass phosphorous removal and nutritive value. Agronomy Journal. 110:879-889. doi:10.2134/agronj2017.08.0480.
DOI: https://doi.org/10.2134/agronj2017.08.0480 Interpretive Summary: Producing bermudagrass hay from fields receiving broiler litter provides both high quality forage for ruminant livestock and a means of exporting manure nutrients to reduce potential surface and ground water impairment; the nutrients taken up by the plants are removed when the hay is harvested. Although a 28 to 35 day harvest interval for bermudagrass provides a reasonable compromise between attaining dry matter (DM) yield and enhancing forage nutritive value parameters, nutrient management considerations may have a greater impact on harvest management decisions when broiler litter is routinely applied. Objectives were to determine (1) the effects of harvest interval (aka, forage maturity) and cutting height on DM yield and nutrient utilization and (2) harvest management strategy that optimizes P removal and nutritive value in the harvested product. Summer growth of ‘Tifton 44’ bermudagrass was harvested at intervals of 21, 35, and 49 days and stubble heights of 1.2 and 3.5 inch in 2005-2007. Studies were conducted at a private farm near Noxapater, MS and at Mississippi State University H. H. Leveck Animal Research Center (South Farm). Each spring, bermudagrass received a split application of 9 ton acre-1 broiler litter (approximately 217 lb acre-1 total N) and a single application of 60 lb acre-1 N as ammonium nitrate. Cumulative DM and uptake of N and P at South Farm increased as maturity increased and as cutting height decreased; whereas, these trends at Noxapater were observed for DM and P uptake only. A 35-day harvest interval appeared to optimize N uptake. Seasonal trends in P uptake closely followed those observed for DM yield and cumulative yield of both parameters increased approximately 30% by cutting at 3-cm height, as compared with 9-cm height. Results of this 3-year study indicated Tifton 44 bermudagrass receiving broiler litter should be harvested every 35 or 49 days and at 3-cm stubble height to provide the best compromise between attaining DM yield, nutrient utilization, and nutritive value to ruminant livestock.
Technical Abstract: Production of bermudagrass [Cynodon dactylon (L.) Pers.] hay to manage manure nutrients may differ from production of hay intended for livestock consumption. This 3-yr study (2005-2007) determined harvest management effects on dry matter (DM) yield, P uptake, and forage nutritive value in ‘Tifton 44’ bermudagrass at Noxapater and South Farm, Mississippi. Fertilization comprised 8.96 Mg litter ha-1 yr-1 (as-is moisture basis) that provided 243 and 122 kg ha-1 of N and P, respectively, supplemented with 67-110 kg N ha-1 (as ammonium nitrate). After an initial harvest in May, summer growth was harvested at 28, 35, and 49 day intervals and at 3- and 9-cm cutting heights. Seasonal trends in P uptake closely followed those observed for DM yield and short stubble increased yields of DM and P by approximately 31%. Prolonged regrowth and 3-cm cutting height resulted in the greatest yields of DM and P. Cumulative P uptake at Noxapater did not differ between 35- and 49-day harvest intervals (21.3 vs. 23.0 kg ha-1); whereas, it was greatest (P < 0.05) at South Farm for 49-day interval (23.9 vs. 25.8 kg ha-1). Prolonged regrowth resulted in crude protein (CP) and in vitro true DM digestibility (IVTDMD) amounts below 95 and 610 g kg-1, respectively, suggesting less of this forage could be consumed by ruminant livestock. In 2007, CP and IVTDMD levels were greatest for 9-cm stubbles. Tifton 44 bermudagrass receiving broiler litter should be harvested every 35 days and at 3-cm stubble height to provide the best compromise between attaining DM yield, nutrient utilization, and forage nutritive value.