Storage and handling can alter the mineralization characteristics of manure

In vitro incubations of manure-amended soil are frequently used to evaluate manure N and C availability. Manures are typically frozen, refrigerated, o r dried prior to analysis. An experiment was designed to evaluate the effec ts of these manure storage methods on C and N mineralization characteristic s. Two dairy slurries were collected and seven treatments, fresh, frozen (4 or 5 wk), refrigerated (1 d, 1 wk, 4 wk), freeze-dried or oven-dried, were compared. Rates and extents of N and C mineralization were determined by a erobic incubation of slurry-amended soil at 25 degrees C. Slurry was added at a rate equivalent to 265 kg N ha(-1) incorporated into the upper 15 cm o f soil. The appearance of NH4+ and NO3- and the production of CO2 were moni tored during 16 wk. Refrigeration or freezing had no effect on slurry N con tent; however, freeze drying and oven drying resulted in N tosses of 30% or more. CO2-C production followed first-order kinetics during 9 wk for all t reatments with approximately 18 to 26% of the slurry C mineralized. Net min eralization of organic N was minimal in all treatments and was not affected by freezing or refrigerating the slurries. With oven dried and freeze-drie d slurries, however, there was a greater immobilization of N when compared with fresh manure. Results indicate that oven drying and freeze drying are unsuitable methods of storage, but the mineralization characteristics of ma nure are not affected by refrigeration or freezing.