Calculation of nitrogen mineralization in soil food webs

In agricultural practices in which the use of inorganic fertilizer is being reduced in favour of the use of organic manure, the availability of nitrogen (N) in soil for plant growth depends increasingly on N mineralization. In simulation models, N mineralization is frequently described in relation to the decomposition of organic matter, making a distinction in the quality of the chemical components available as substrate for soil microbes. A different way to model N mineralization is to derive N mineralization from the trophic interactions among the groups of organisms constituting the soil food web. In the present study a food web model was applied to a set of food webs from different sites and from different arable farming systems. The results showed that the model could simulate N mineralization rates close to the rates obtained from in situ measurements, from nitrogen budget analyses, or from a decomposition based model. The outcome of the model suggested that the contribution of the various groups of organisms to N mineralization varied strongly among the different sites and farming systems.