Towards an operational forecast of nitrogen flows resulting from manure spreading: parameterization of a dynamic model for the simulation of manure nitrogen transformations (STAL)

Abstract

The European Directive on Nitrates and the publication of the Code of Good Agricultural Practices nowadays encourage the better use of effluents from livestock rearing, since their careless use, which is often seen, leads to water and air pollution. This being so, it seems important to improve the prediction of the nitrogen fertilisation value of livestock effluents, as compared with existing operational models, and to make available tools capable of evaluating the environmental impact of agricultural practices. To respond to this need, a dynamic simulation model of transformations of nitrogen from slurries, called STAL, was developed and parameterised; the novelty of the procedure rests in the modelling coupled with volatilisation and biotransformations (i.e. nitrification, immobilisation and mineralisation), which takes into account competition between processes. STAL brings together effects of weather, slurry composition and application methods on the fertilising value of the effluent and contributes to the environmental evaluation by calculating ammonia volatilisation and nitrification dynamics. The accent has been put on the creation of an operational model, calibrated from readily acquired data, and evolving so as to easily incorporate new functions and processes.