Predicting grass growth on farm, utilisation of the MoSt Grass Growth model

The Moorepark St Gilles Grass Growth (MoSt GG) model was developed to predict grass growth, grass nitrogen (N) content and N leaching on a daily basis depending on soil type, fertilisation and grazing management. The inputs required are at the paddock level and are soil type (% sand, % clay), percentage of organic matter, the weather historical and forecast (daily rainfall, solar radiation and temperature), the N fertilisation (type and amount), and the defoliation management (day of grazing/cutting, number of animals on the paddock, post grazing/cutting height). All the information concerning N fertilisation and defoliation management are present in a decision support tool called PastureBase Ireland (PBI). The model was evaluated against data from PBI (2013-2018) on a number of farms. The model showed good accuracy and was able to take into account variation between the different years and grazing/fertilisation management. Since January 2018, the MoSt GG model was used weekly to predict grass growth for three farms. The model used historical management (from PBI) and weather data, as well as weather forecast provided by Met Eireann, to predict the grass growth of the following week. This live evaluation highlighted a number of strengths and weaknesses of the model during the challenging year that was 2018. The prediction of grass growth helped the farm managers' weekly management decisions. Since January 2019, the model is being used on 40 farms. Grass growth is communicated to farmer and farm manager through WhatsApp at least once a week. The next step will be the full integration into PBI.