Harvest Management Effects on ‘Tifton 44’ Bermudagrass Phosphorus Removal and Nutritive Value

Abstract

Core Ideas The impact of harvest management on forage nutritive value is vital to farm income.Results validate management practices commonly used but heretofore without statistical basis.Bermudagrass P removal maximized with prolonged harvest interval and short stubble height.Forage nutritive value was similar between stubble heights when harvested every 35 d. Haying bermudagrass [Cynodon dactylon (L.) Pers.] to maximize recovery of P applied in broiler litter may adversely affect forage quality. This 3‐yr study (2005–2007) determined harvest management effects on dry matter (DM) yield, P removal, and forage nutritive value in ‘Tifton 44’ bermudagrass at Noxapater and South Farm, MS. Fertilization annually comprised 8.96 Mg ha−1 broiler litter (as‐is basis) that provided 243 and 122 kg ha−1 of N and P, respectively, supplemented with 67–110 kg ha−1 N (as ammonium nitrate). After an initial harvest in May, forage was harvested at 28‐, 35‐, and 49‐d intervals and at 3‐ and 9‐cm residual cutting heights. Seasonal trends in P removal closely followed those observed for DM yield and short stubble increased yields of DM and P by approximately 31%. Prolonged regrowth and 3‐cm stubble height resulted in the greatest yields of DM and P. Annual P removal at Noxapater did not differ between 35‐ and 49‐d harvest intervals (21.3 vs. 23.0 kg ha−1); whereas it was greatest (P < 0.05) at South Farm for 49‐d intervals (23.9 vs. 25.8 kg ha−1). Prolonged regrowth resulted in crude protein (CP) and in vitro true DM digestibility (IVTDMD) below 95 and 610 g kg−1, respectively, suggesting less forage could be consumed by ruminant livestock. In 2007, CP and IVTDMD levels were greatest for 9‐cm stubble. Tifton 44 bermudagrass receiving litter should be harvested every 35 d and at 3‐cm stubble height to provide the best compromise between DM yield, nutrient removal, and forage nutritive value.