Nutritive value and nutrient uptake of sorghum-sudangrass under different broiler litter fertility programs

Broiler (Gallus gallus) litter fertility regimes and nutrient removal by sorghum-sudangrass [Sorghum bicolor (L.) Moench] are not well defined. The objective of this study was to determine broiler litter fertility regimes for sorghum-sudangrass that would maximize nutrient removal and produce comparable forage nutritive value compared with inorganic fertilizers while reducing potential soil nutrient accumulation. A randomized, complete-block experiment with four replications and four treatments (litter applied at recommended nitrogen [N] rate [Litter-N], recommended phosphorus [P] rate plus supplemental inorganic N [Litter-P+N], recommended P rate [Litter-P], and inorganic fertilizer [INORG]) was established. Acid detergent fiber (ADF), neutral detergent fiber (NDF), crude protein (CP), F, Cu, Fe, and Zn were determined. Treatments did not affect ADF, NDF, Cu, or Fe in 2001, whereas ADF and NDF were similar for INORG and Litter-N in 2002. Greatest P concentrations were observed in Litter-N and Litter-P plots. Crude protein was greatest for INORG plots, similar for Litter-P+N and Litter-N treatments, and lowest for Litter-P plots. Treatments affected Cu and Zn: Forage from Litter-N plots contained 44% greater forage Cu than those from Litter-P plots in 2003. Iron concentration for 2003 was 60% higher than for 2001 in Litter-N plots, and there were 22% and 30% increases in P uptake in 2003 compared with 2001 for the Litter-N and Litter-P+N plots, respectively. Lower rates of broiler liner, applied based on the P requirement and supplemented with inorganic N, can produce similar forage nutritive value to that fertilized with inorganic fertilizer only or broiler litter applied to meet crop N requirements.