Developing a predictive model for grass growth in grass-based milk production systems

In temperate regions grazed grass is the most economical means of feeding dairy cows. Grass growth is highly variable within and between years. A model capable of simulating daily grass growth depending not only on weather conditions but also on N fertiliser application and farm management would provide valuable information allowing farmers to make better management decisions around supplementation, silage making, fertilisation and grazing. The Moorepark Grass Growth Model (MGGM) is a mechanistic grass growth model developed to take into account weather, soil water and soil N dynamics. The response of the model to weather conditions, frequency of harvesting, initial soil N content and N fertiliser application was evaluated. The responses from the model were comparable with published studies. The MGGM responded coherently to grass harvesting and N fertiliser application and can predict the grass growth rate taking into account management and weather