Le modèle « Moorepark - Saint-Gilles Grass Growth » (MoSt GG) de prévision de croissance de l'herbe en conditions de pâturage

The Moorepark Saint-Gilles Grass Growth (MoSt GG) model is a dynamic and mechanistic model that simulates grass growth, grass nitrogen (N) content, and N leaching. It incorporates information on weather conditions, N fertilisation, and defoliation events (grazing or cutting), and it utilises a daily time step. The model was used to predict what would happen under grazing conditions over 10 weather years and 4 levels of N fertilisation. The model's results for annual growth and response to fertilisation matched previously obtained empirical observations. Notably, the response of the grass decreased as fertiliser level increased. The model did a good job of simulating the efects of climatic variability among years: overall grass growth was low in years with dry summers. Furthermore, the results revealed a relationship among N leaching, the annual number of grazing days, and autumn rainfall.