Empirical model for mineralisation of manure nitrogen in soil

A simple empirical model was developed for estimation of net mineralisation of pig and cattle slurry nitrogen (N) in arable soils under cool and moist climate conditions during the initial 5 years after spring application. The model is based on a Danish 3-year field experiment with measurements of N uptake in spring barley and ryegrass catch crops, supplemented with data from the literature on the temporal release of organic residues in soil. The model estimates a faster mineralisation rate for organic N in pig slurry compared with cattle slurry, and the description includes an initial N immobilisation phase for both manure types. The model estimates a cumulated net mineralisation of 71% and 51% of organic N in pig and cattle slurry respectively after 5 years. These estimates are in accordance with some other mineralisation studies and studies of the effects of manure residual N in other North European countries