Cotton Lint Yield and Soil Quality as Influenced by Continuous Poultry Litter Application for 5-yr.

Utilizing poultry litter as N source for row crops such as cotton (Gossypium hirsutum L.) would be an option to dispose it of safely. In a 5-yr study, three sources of nitrogen: urea, fresh poultry litter (FPL), and composted poultry litter (CPL) at the rate of 40, 80, and 120 kg plant available N ha^-1 with and without nitrification inhibitor, carboxymethyl pyrazole (CP) were evaluated for cotton yield on a Decatur silt loam soil in Alabama from 1994 to 1998. Among the three N sources, FPL produced the highest mean lint yield over the five year period (1492 kg ha^-1) compared to CPL (1392 kg ha^-1) and urea (1391 kg ha^-1). The nitrification inhibitor, CP, had no significant effect on lint yield. Application of poultry litter maintained soil pH (0-30 cm depth) where as application of urea resulted in a decline in pH. The inhibitor, CP, significantly reduced the NO₃^- -N formation in all N sources for 41 days following application. Over the longer period of time, very minimal changes in nitrate concentrations were observed due to change in rates or sources of N. Over the experimental period, P concentration increased significantly (by 74%) in CPL applied plots (17.7 mg/kg) but not in FPL plots (1.5 mg/kg). Concentrations of K and Mg increased significantly both in FPL (93 and 25 mg/kg, respectively) and CPL (127 and 36 mg/kg, respectively) applied plots by the end of 5 yr period.  These results show that well planned application of fresh poultry litter for cotton production is safe and solves poultry litter disposal problem.