|LANG, DAVID - Mississippi State University|
Submitted to: Grass and Forage Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/29/2016
Publication Date: 9/9/2016
Citation: Read, J.J., Lang, D.J., Aiken, G.E. 2016. Seasonal nitrogen effects on nutritive value in binary mixtures of tall fescue and bermudagrass. Agronomy Journal. 72:467-480.
Interpretive Summary: Tall fescue (cool-season) and bermudagrass (warm-season) are grown widely in the southeastern USA and probably receive more poultry litter (a mixture of manure, wasted feed and bedding material) than any other perennial forage. Grazing mixed tall fescue and bermudagrass swards is commonly practiced, and while high forage yields help in meeting nutrient management goals, an important consideration for livestock producers is the quantity of available and digestible nutrients stored and the level of animal performance that will result from feeding the forage. Researchers in Mississippi conducted field studies in 2008-2010 to determine the effects of binary mixture and seasonal N treatments on biomass yield, protein content, and fiber analysis (an estimator of forage digestibility) in cuttings of tall fescue-bermudagrass forage mixtures. The effect of binary mixture was compared with bermudagrass not overseeded with tall fescue. Three applications of N fertilizer (34-0-0) were combined with two applications of broiler litter, each at various times of the growing season (October – July), to compare ‘N-timing’ treatments of ‘Fescue Bias’ (autumn-winter), ‘Bermudagrass Bias’ (spring) and ‘Optimal’ (winter-spring). The Fescue Bias treatment offered significantly greater yield of forage produced in cool-season. When data were averaged across harvest dates, the Fescue Bias treatment also offered significantly greater protein content and forage digestibility, particularly in the binary mixture of cultivar Jesup MaxQ tall fescue and cultivar Tifton 44 bermudagrass. However, greater nutritive value of the Jesup-Tifton 44 mixture must be balanced against slightly lower total biomass, due to dampening of bermudagrass growth in summer. Results indicated that application timing of fertilizer N (organic and inorganic) in an 11-month forage production system has implications for optimal utilization of tall fescue and bermudagrass stands both as a pasture and a hay source.
Technical Abstract: Year-round forage production is feasible in much of the southeastern USA through utilization of cool- and warm-season forages. This study determined changes in herbage nutritive value in binary mixtures of cool-season, tall fescue [Schedonorus arundinaceus (Schreb.) Dumort], and warm-season, bermudagrass [Cynodon dactylon (L.) Pers.], when poultry litter and fertilizer N are applied to coincide with seasonal growth activities. Two tall fescue cultivars, ‘Flecha MaxQ’ (summer-dormant) and ‘Jesup MaxQ’ (summer-active) were drill-seeded in 2007 into established swards of ‘Russell’ and ‘Tifton 44’ bermudagrass. Three seasonal N treatments were each composed of 8.6 Mg litter ha-1 (as-is moisture basis) split into two applications per season with additional 168 kg N ha-1 split into three applications per season. Treatment effects on crude protein (CP), acid detergent fiber (ADF), neutral detergent fiber (NDF), and in vitro true digestibility (IVTD) were determined in samples of mixed herbage harvested in April, May, July, August, and September 2009 and 2010. In general, nutritive value was greatest for Jesup-Tifton 44 mixture, based on high CP and IVTD, and low ADF. As compared to January/March seasonal N treatment that applied litter and fertilizer N in January–July, applying N before April increased (P < 0.01) April and May dry matter (DM) yields of mixed herbage, July IVTD (603 vs. 629 g kg-1, 2 yr average), and August IVTD (618 vs. 660 g kg-1). Results suggest application timing of poultry litter and N to favor growth of the cool-season grass can enhance nutritive value of tall fescue-bermudagrass production systems.