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 mi neralization. In simulation models, N mineralization is frequently des cribed in relation to the decomposition of organic matter, making a di stinction in the quality of the chemical components available as subst rate for soil microbes. A different way to model N mineralization is t o derive N mineralization from the trophic interactions among the grou ps 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 th e model could simulate N mineralization rates close to the rates obtai ned from in situ measurements, from nitrogen budget analyses. or from a decomposition based model. The outcome of the model suggested that t he contribution of the various groups of organisms to N mineralization varied strongly among the different sites and farming systems.