Managing harvest of ‘Russell’ and ‘Tifton 44’ bermudagrass receiving broiler litter for nutritive value and phosphorus removal

摘要

Abstract Bermudagrass Cynodon dactylon (L.) Pers. hay fields receiving broiler litter offer a means to both produce high quality forage and export excess manure nutrients, for example P. This 3‐yr study determined the nutritive value, P removal, and soil P for ‘Russell’ and ‘Tifton 44’ bermudagrass receiving 4 ton ac−1 broiler litter and 98 lb ac−1 N (as NH4NO3) annually and cut at 21‐, 35‐, and 49‐d intervals with residual stubble heights of 1.2 and 3.5 inches. Forage cut every 49 d at 1.2‐inch stubble height had the greatest dry matter (DM) yield and low nutritive value; weighted‐sum crude protein (CP) ranged from 7.2 to 8.2 and weighted‐sum in vitro true DM digestibility (IVTDMD) ranged from 56.8 to 62.0, depending on year. With a 35‐d interval, forage CP and IVTDMD amounts generally exceeded 9.6 and 62.0, respectively. Forage IVTDMD was greater in Tifton 44 than Russell in 2006 and 2007, when values with a 35‐d interval were approximately 3.0 and 0.3 greater, respectively. Cutting at a 1.2‐inch height increased P removal by approximately 23 in Russell and 30 in Tifton 44 compared with a 3.5‐inch height. Phosphorus removal was maximized with a 49‐d interval and 1.2‐inch height in 2005 (29.8 lb ac−1) and 2006 (19.3 lb ac−1) and with a 35‐d interval and 1.2‐inch height in 2007 (29.3 lb ac−1). Managing the balance between high DM and nutritive value in both cultivars can be achieved with a 35‐d interval and 1.2‐inch height. A prolonged harvest interval of 49 d is a valuable consideration for P removal via biomass.