Storage and Handling Can Alter the Mineralization Characteristics of Manure
1999
Van Kessel, J. S. | Reeves, J. B. | Meisinger, J. J.
In vitro incubations of manure-amended soil are frequently used to evaluate manure N and C availability. Manures are typically frozen, refrigerated, or dried prior to analysis. An experiment was designed to evaluate the effects of these manure storage methods on C and N mineralization characteristics. 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 aerobic incubation of slurry-amended soil at 25°C. Slurry was added at a rate equivalent to 265 kg N ha⁻¹ incorporated into the upper 15 cm of soil. The appearance of NH⁺₄ and NO⁻₃ and the production of CO₂ were monitored during 16 wk. Refrigeration or freezing had no effect on slurry N content; however, freeze drying and oven drying resulted in N losses of 30% or more. CO₂-C production followed first-order kinetics during 9 wk for all treatments with approximately 18 to 26% of the slurry C mineralized. Net mineralization of organic N was minimal in all treatments and was not affected by freezing or refrigerating the slurries. With oven-dried and freeze-dried 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 manure are not affected by refrigeration or freezing.
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