Using a climate-driven farm model to predict pasture mass for individual paddocks on New Zealand dairy farms

Accurate prediction of pasture mass on dairy farms would allow for greater precision and feed allocation planning, and therefore greater utilisation and more profit. Current methods to collect these data, e.g. by rising plate meter or visual assessment, are tedious and time consuming. Daily pasture growth rate (kg DM/ha/ day) can be added to a measured post-grazing residual to estimate the increase in pasture mass after a grazing or cutting event. A whole farm model (WFM) was found to predict daily pasture growth rates from climate data with an acceptable level of accuracy on a farm scale. However, growth rates can vary by up to 100 % between individual paddocks, making it necessary to modify predicted farm-scale growth rates before applying them to individual paddocks. A prototype spreadsheet decision support tool was developed that applies different approaches to modifying pasture growth rates for individual paddocks. Farmers can receive daily growth rates via e-mail, and this spreadsheet enables them to combine these growth rates with observed pasture mass readings to derive daily predicted pasture mass on a paddock scale