Profile of Nitrogenous Compounds in Soil Applied with High-N Organic Fertilizers.

Nitrogen is needed in greatest quantity among the nutrients for non-legume crops, and oftentimes limits crop production. Most Georgia soils are low in residual nitrogen because of low inherent organic matter and leaching losses for being sandy. Nitrogen limitation is even more common in organic farming such that in-season fertilization is usually resorted to correct the deficiency of this nutrient. A study was conducted to determine the rate of N mineralization and assess the profile of nitrogenous compounds following the application of high-N organic fertilizers to a low organic matter and sandy Georgia soil. Three high-N organic fertilizers, blood meal, feather meal, and bone meal, were added to soil at standard rate of 150 kg N ha^-1.  Treated soils or soil blends including untreated soil were incubated for 10 weeks at 25^oC and at optimal water content (65% of field capacity). Each soil blend was sampled at different time intervals and subsequently analyzed for total N and inorganic N (NH4 and NO3).   The soils were also extracted of peptides and analyzed by HPLC and MALDI-MS to evaluate the profile of protein sources degradation. Nitrogen mass balance was calculated at each sampling period.