Mineralizable nitrogen in broiler litter: II. Effect of selected soil characteristics

Broiler litter (BL) is a mixture of chicken (Gallus gallus domesticus) manure and bedding material that is commonly used as fertilizer for crops and pastures. Knowledge of the factors that determine the amount of potentially mineralizable N in BL is needed to estimate adequate application rates. Limited evidence suggests that soil characteristics such as texture can significantly affect the amounts of net N mineralized from BL, This work was conducted to compare the kinetics of N mineralization of the same BL in nine different soil samples, and to determine the effect of selected soil characteristics on the amount and rate of decomposition of potentially mineralizable N in BL, Samples from the same BL were mixed with nine soils (150 mg organic N kg(-1), -0.02 MPa) and incubated at 25 degrees C for 146 d, A two-pool, first-order kinetics model adequately described cumulative net N mineralized from the litter, which ranged from 364 to 784 g N kg(-1) organic N. Multiple regression analysis generated statistically significant equations that identified the ratio of (sand content/water content at field capacity) and pH as soil characteristics with a significant effect on the fast and slow pools of mineralizable N. Combining a predictive equation for total mineralizable N based on BL characteristics with a predictive equation for total mineralizable N based on soil characteristics, we generated an equation that predicts total mineralizable N based on BL and soil characteristics. Future work should further test this equation and correlate plant N uptake with predicted values of potentially mineralizable N in BL.