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°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.