Poultry Litter and Tillage Influence on Corn Production and Soil Nutrients on a Silt Loam Soil in Kentucky.

Broiler (Gallus Gallus) litter, a rich source of plant nutrients, is generated in large quantities in southeastern USA where many row crops, such as corn (Zea Mays L.), are also extensively cropped. However, the use of broiler manure as an economical alternative source of nutrients for corn production has not been extensively explored in this region.  This study was conducted to examine the use of broiler litter as a source of nutrients for corn production, as influenced by tillage and litter rate, and any residual affects following application. The treatments consisted of two rates of broiler litter application, 11 and 22 Mg ha^-1, and one rate of chemical fertilizer applied under no-till and conventional tillage systems. Treatments were applied on the same plots and corn was planted each year from 1998 to 2001. Two years out of the four-year experiment, broiler litter application produced significantly greater corn grain yield than equivalent chemical fertilizer application and produced similar grain yield in the other two years.  Corn grain yield was significantly greater under no-till in 1999, but significantly greater under conventional-till in 2000, and no difference between the two tillage systems were observed in 1998 and 2001.  With four years of litter application, Mehlich-3 P increased from an initial 18 mg kg^-1 to 156 mg kg^-1 with 11 Mg ha^-1 litter rate and to 257 mg kg^-1 with 22 Mg ha^-1 litter.  Six kg ha^-1 of P applied in poultry litter increased Mehlich-3 P by 1 mg kg^-1.  Modest increases in Mehlich-3 Cu and Zn did not result in phytotoxic levels.  This study indicated that an optimum rate of broiler litter as a primary fertilizer at 11 Mg ha^-1 applied in four consecutive years on a silt loam soil produced corn grain yields similar to chemical fertilizer under both no-till or conventional tillage systems and kept soil test P, Cu and Zn levels below values considered to be harmful to surface water quality or the crop.