Effects of Broiler Litter in an Irrigated, Double-Cropped, Conservation-Tilled Rotation

Broiler production is increasing rapidly in the Southern Coastal Plain, and little research has been conducted to evaluate broiler litter applications on the sandy soils of the region. We conducted a 4-yr field study to determine optimum rates of broiler litter, its economic value, changes in soil tests to a depth of 90 cm, and effects on pathogens and nematodes. Summer crops were cotton (Gossypium hirsutum L.), pearl millet [Pennisetum glaucum (L.) R. Br.] for grain, and peanut (Arachis hypogaea L.). Winter crops were wheat (Triticum aesitivum L.) and oilseed canola (Brassica napus L.). Litter rates were 0, 4.5, 9.0, and 13.5 Mg ha -1 for each crop. Litter application increased yields of cotton, pearl millet, wheat, and canola and decreased yield of peanut. Average crop value increase from application of a megagram of broiler litter was estimated to be $42 ha -1 yr -1 when the application was made to all crops and $68 ha -1 yr - when none was applied to peanut. The mean cost of applied litter was approximately $12 Mg -1 . Surface soil P, K, Cu, Zn, and Mn were increased in direct relation to litter rate. Data indicate that it would be prudent to limit applications to about 4.5 Mg ha -1 . Litter applications had little effect on soil nematodes, but Rhizoctonia limb rot (Rhizoctonia solani AG-4) of peanut increased. Lodging of canola, due to Sclerotinia spp., was doubled by any application of broiler litter.