How does measuring methodology impact N mineralization in controlled conditions and relations to soil biological parameters: air dried versus fresh soil

Predictions of N mineralization are still difficult but maybe this is due to the methodologies. Many soil tests have been proposed to predict N mineralization between field and laboratory experiment. Incubations of soil in the laboratory under controlled environmental conditions are most commonly used to assess N mineralization rates both from SOM and from added organic materials. However, predicting N mineralization due to the methods (the impact of using air-dried and fresh soil) has never been assessed before. If the results differ between the methods commonly used, there is a serious problem. Therefore, the objective of this study was to evaluate the influence of the incubation methods (air-dried vs fresh soil) to predict N mineralization. The N mineralization potential from fifteen agricultural soils in West and East Flanders – Belgium, were determined by aerobic incubation methods used air-dried and fresh soil at (20 – 25⁰C) for 84-days in the laboratory. The results indicated that total mineral nitrogen (NH4⁺ + NO3^-) concentrations and carbon content of microbial biomass (MBC) did not differ significantly between these methods. Nitrogen was mineralized in fresh soil incubations (0.36 mg N. kg^-1 soil day ^-1) while in air-dried soil (0.31 mg N kg^-1 soil day ^-1). Thus, the results generate that it may be conceivable to predict N mineralization by these two methods in controlled conditions.