Thursday, November 16, 2006 - 8:45 AM

Nutrient Release from Mineralization of Poultry Litter under Controlled Conditions.

Mingxin Guo and Maria Labreveux. Delaware State Univ, 1200 N. DuPont Hwy, Dover, DE 19901

Application of poultry litter at agronomic rates is the key to control nutrient runoff losses from cropland receiving the organic waste. To establish agronomic application rates, nutrient release and supplying capacity of poultry litter following land application has to be addressed first.  Alum-treated (87 g kg-1) and non-treated poultry litters were packed in PVC columns (15 cm i.d.) at 34.4 ton ha-1 to a depth of 5 cm and leached intermittently with deionized water.  Leachate was collected and analyzed for various nutrients.  The poultry litter leachate contained high concentrations of dissolved organic carbon (DOC, 33-11800 mg L-1), dissolved nitrogen (6-2700 mg L-1), dissolved phosphorus (50-224 mg L-1), potassium (20-6000 mg L-1), and other inorganic salts. The pH and electrical conductivity were 7.0-8.7 and 0.3-24 dS m-1, respectively. Following 190 days and 188 cm cumulatively-applied water, per kg of non-treated poultry litter released 121.7 g of dissolved organic carbon (DOC), 34.9g of nitrogen (N, 14.9 g in NH4+, 0.4 g in NO3-, and 0.13 g in NO2-), 11.5 g of phosphorus (P, 10.1 g in inorganic P), and 111.6 g of potassium (K) in the leachate; the alum-treated litter released (per kg) 64.3 g of DOC, 41.4 g of N(31.2 g in NH4+, 2.2 g in NO3-, and 0.06 g in NO2-), 1.8 g of P (1.1 g in inorganic P), and 122.4 g of K.  Release of DOC, total dissolved N, NH4+-N, and K were described by a first order Exponential Rise to Maximum model, while release of total dissolved P and inorganic P were described by a Power equation.  Release of NO3- and NO2- were best described by a Sigmoidal process. Alum amendment significantly decreased release of P and DOC, but increased release of Ca2+, Mg2+, and SO42-.