Mineralizable nitrogen in broiler litter: I. Effect of selected litter chemical characteristics

Broiler (chicken, Gallus gallus domesticus) litter is a mixture of manure and bedding material that is generated in large amounts by the broiler industry. this litter is typically applied to land as fertilizer, at rates estimated to supply adequate N. Estimation of rates is currently hampered by the lack of rapid methods to determine mineralizable N in BL. this study was conducted to compare the kinetics of N mineralization of 15 BL samples, and to evaluate selected chemical characteristics of the litter as predictors of mineralizable N. Broiler litter samples were mixed with samples of Cowarts soil (150 mg organic N kg(-1) soil, -0.02 MPa) and incubated at 25 degrees C for 112 d. cumulative net N mineralized was fitted to a two-pool, first-order model, to determine the size of fast and slow pools of mineralizable N. The fast N pool varied from 116 to 569 g N kg(-1) organic N (ON), and could be predicted from uric acid-N concentration in the litter (r(2) = 0.92). The size of the slow N pool did not vary significantly among BL samples; (309 +/- 94 g N kg(-1) ON). Total mineralizable N (fast + slow N pools) ranged from 465 to 868 g N kg(-1) ON, and could be predicted from uric acid-N and total N concentrations (R-2 = 0.91), or from uric acid-N concentration and C/N of the litter (R-2 = 0.95). the simplicity of the chemical indices involved should make this approach attractive to estimate mineralizable N in BL.