Rapid methods to determine potentially mineralizable nitrogen in broiler litter

Although broiler (chicken, Callus gallus domesticus) litter has long been u sed as a fertilizer, estimating the rate required to supply a desired amoun t of plant-available N is still hampered by the lack of rapid methods to es timate potentially mineralizable nitrogen (PMN). Previous research has sugg ested that near infrared reflectance spectroscopy (NIRS) and certain poultr y litter characteristics, such as water-soluble organic nitrogen (WSON), ma y be useful for estimating PMN, The objectives of this study were to evalua te NIRS and WSON as tools to estimate PMN in broiler litter. Sixty sieved ( 2 mm) and freeze-dried broiler litter samples were mixed with Cowarts sandy loam soil (fine-loamy, kaolinitic, thermic Typic Kanhapludult) and incubat ed at 25 degreesC for 112 d. Cumulative net N mineralized with time was fit ted to a single-pool exponential model to determine PMN for each broiler li tter sample. The PMN values obtained were regressed against NIRS (780 to 25 00 nm) and WSON measurements. We found strong relationships between measure d- and NIRS-predicted PMN (R-2 = 0.82), and between measured PMN and WSON ( R-2 = 0.87). These results demonstrate the feasibility of using either of t hese two methods to estimate PMN in broiler litter. Future work should Furt her test both methods for their ability to estimate mineralizable N in whol e, moist broiler litter under field conditions.