Dissolved Organic Nitrogen as proxy for mineralisation?

Strong relationships between Extractable Organic N (EON) and N mineralization suggest that they can be used to assess the N mineralization potential of soils. EON is often used to proxy Dissolved Organic Nitrogen (DON), which is assumed to play an intermediate role in N mineralization. We tested whether EON relates to N mineralization and how this relation is affected by the extraction methodology used. We synthesized results from 171 papers on correlation coefficients between EON and N mineralization using meta-analysis. EON was positively related to N mineralization, and its size explained 14-65% of the variation in N mineralization. Best results were obtained with hot CaCl2 and acid KMnO4 as extractants. EON extracted with alkali solutions explained less of the variation in N mineralization than the other soil tests. There was no direct relationship between the intensity of extraction and the performance of EON as predictor for N mineralization. When EON levels are used to make fertilizer-N recommendations, the extraction methodology used to develop the above described relationship is closely followed