John J. Read, 810 Hwy 12 East, PO Box 5367, USDA-ARS, Mississippi State, MS, Ardeshir Adeli, Genetics and Precision Agriculture Research Unit, USDA-ARS, Mississippi State, MS and David J. Lang, Mississippi State University, Mississippi State, MS
Land application of broiler litter provides essential nutrients for tall fescue [Schedonorus arundinaceus (Schreb.) Dumort] hay production, but often results in nutrient accumulation in soils over time. This 3-yr study (2006-2008) determined nutrient uptake (kg ha-1) in two summer-active cultivars, Jesup MaxQ and Kentucky 31, and a summer-dormant cultivar, Flecha MaxQ, at litter rates of 0, 4.5, 9.0, 13.4, and 17.9 Mg ha-1 yr-1 (as-is moisture basis), as compared to NPK fertilizer (224-112-224 kg ha-1). The soil had no history of litter and mapped as Houston clay (fine, montmorillonitic, thermic, Typic, Chromuderts). Fertilization treatments were split-applied in autumn and spring and forage was harvested at early-, mid- and late-season. Soil tests in autumn 2008 indicated greater pH and Mehlich-3 extractable P, K, Cu, and Zn in 4.5 Mg litter ha-1 than NPK fertilizer. Total N uptake in 2008 increased linearly as litter rate increased and this relationship was significant (P < 0.01) in Kentucky 31 (slope = 12.2), Flecha (slope = 10.2), and Jesup (slope = 9.2). When data were averaged across early- and mid-season harvests in 2006 and 2007, cumulative N uptake averaged 118 kg ha-1 with NPK fertilizer and values increased linearly from about 8 to 96 kg ha-1 across five litter rates. Yields of dry matter and nutrients were approximately 2.2-fold greater with NPK fertilizer than 9.0 Mg litter ha-1, two treatments with comparable N rates. Herbage crude protein (CP) concentration in the NPK fertilizer and 13.4 and 17.9 Mg litter ha-1 treatments was lower (P < 0.05) in Flecha than either Jesup or Kentucky 31. Significantly less CP concentration in Flecha was associated with greater dry matter yield and cumulative K uptake, as compared with Jesup or Kentucky 31. The summer-dormant cultivar appeared to offer an early-season productivity benefit and annual nutrient uptake that was comparable to traditional, summer-active cultivars.