Predicting soil N mineralization using organic matter fractions and soil properties: A re-analysis of literature data

Extractable organic matter (EOM) fractions have been used to assess the capacity of soils to supply nitrogen (N), but their role in N mineralization and their potential to improve agricultural fertilizer management are still under debate. This paper shows evidence that the relationship between EOM and soil N supply is an indirect relationship reflecting the soilsʹ organic matter content. Data from 59 published experiments were re-analyzed using multivariate PLS modelling. Nitrogen mineralization was primarily related to the size of total and extractable organic matter fractions whereas variables reflecting soil texture and organic matter quality were less important. All EOM fractions reflected the soil organic matter content of the soil rather than a specific bioavailable fraction. There is strong need for research that explores the biochemical basis for relationships among total organic matter, extractable organic matter and soil N mineralization using mechanistic approaches.