NITROGEN RECOVERY FROM BROILER LITTER IN A WHEAT-MILLET PRODUCTION SYSTEM

Nitrogen (N) released through mineralization from broiler litter can s upply the N requirements for crops, but litter may cause yield reducti ons and loss of fertilizer value if applied in excess of crop needs. A field study was conducted over two years at Crossville, AL, to determ ine the fate of N in a winter-wheat (Triticum aestivum L.) - pearl-mil let (Pennisetum americanum L.) crop rotation. Soil and plant N content s were determined after fall application of 0, 9, or 18 Mg ha-1 litter supplemented with 0 or 34 kg ha-1 fall-applied N and 0, 22, 44, or 66 kg ha-1 of spring-applied N fertilizer. Millet followed wheat harvest with no additional N added to the soil Broiler litter applied at 9 Mg ha-1 eliminated the need for fall-applied N fertilizer and reduced th e need for spring-applied N to 22 kg ha-1. The 18-Mg ha-1 litter rate reduced grain yield, and the reduction increased as spring-applied N r ates increased. In the first year, N removed in wheat grain plus mille t tissue averaged 44 and 16% of N from 9 and 18 mg ha-1 litter, respec tively. In the second year, N removal from the litter treatments was 1 7 and 14% of N contained in 9 and 18 Mg ha-1 litter, respectively. The results of this study suggest that 9 Mg ha-1 of broiler litter with a pproximately 22 kg ha-1 of supplemental spring-applied N may be optimu m for winter-wheat production. A summer annual such as pearl millet fo llowing winter wheat can utilize residual N and decrease the potential for N loss via leaching.