Submitted to: Forage and Grazinglands
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/4/2010
Publication Date: 9/1/2010
Citation: Read, J.J., Aiken, G.E., Lang, D.E. 2010. Herbage nutritive value of tall fescue fertilized with broiler litter and inorganic fertilizer. Forage and Grazinglands. Available: http://www.plantmanagementnetwork.org/sub/fg/research/2010/value. Interpretive Summary: Tall fescue, a perennial, cool-season forage grass, is depended on heavily for livestock production. With the increase in poultry production in many regions of the southeastern USA, more forage producers are using broiler litter (a mixture of manure, wasted feed and local bedding material) as fertilizer. Few studies have examined broiler litter effects on the nutritive value of tall fescue and other cool-season forage grasses. Researchers in Mississippi conducted field studies in 2005-2007 to determine the trends in forage biomass, protein content, and fiber analysis (an estimator of forage digestibility) across five litter rates, as compared to commercial fertilizer. Based on split-applications in April and October, forage biomass was greatest at midseason with commercial fertilizer and at late season with broiler litter. Soils analysis suggested that in addition to the carbon and other nutrients provided by litter, increased phosphorus and potassium nutrition influenced tall fescue response to broiler litter. The most notable trend was a nearly linear increase in crude protein content at litter rates that exceeded 4.48 Mg/ha per year, particularly at the midseason and late-season harvests. Applying more than 8.9 Mg/ha litter per year elevated soil phosphorus, zinc and copper. Based on digestibility values comparable to commercial fertilizer, the nutritive value of tall fescue hays would not be substantially reduced when broiler litter is the sole nutrient source.
Technical Abstract: Broiler litter is widely used as a fertilizer on tall fescue [Lolium arundinaceum (Schreb.) S. J. Darbyshire], but little is known of forage quality responses to litter. Field studies were conducted to determine (1) the trends in crude protein (CP), neutral detergent fiber (NDF), and in vitro digestible dry matter (IVDDM) in ‘Jesup’ tall fescue at five rates of litter and three harvest dates (early, mid-, and late), and (2) treatment effects on soil P, Cu and Zn (0-15 cm depth). In general, highest forage quality, based on low NDF and high CP and IVDDM, was obtained at the early-season harvest in 2005 and 2006. Across litter rates, forage biomass at midseason and late-season in 2006 and 2007 increased by about 87% (~1000 to 2875 kg/ha). Litter rates above 4.48 Mg/ha led to significant (P<0.01) reductions in NDF and nearly linear increases in CP. The trend for increased quality with litter rate was significant (P<0.05) at late season in 2006, when CP increased 54%, NDF decreased 6%, and IVDDM increased 1%. Results suggest 8.96 Mg/ha/yr was the best comprise for producing high biomass and forage quality. Soils analysis in fall 2007 found Mehlich-3 P was least in CF and 4.48 Mg/ha litter treatments, elevated significantly in 8.96 Mg/ha litter, and greatest in 17.92 Mg/ha. Based on acceptable IVDDM values comparable to the CF treatment (500 and 700 g/kg), forage quality in tall fescue would not be substantially reduced when broiler litter is the sole nutrient source.