Estimating farm pasture cover using a limited number of paddocks

The amount and rate of change of pasture availability on dairy farms, often referred to as farm pasture cover, expressed as kg DM/ha, is a key metric for making daily and seasonal management decisions. However, regular farm walks to determine farm pasture cover are conservatively estimated as occurring on only 10% of Tasmanian dairy farms with, “lack of time” quoted by farmers as the main reason for this not occurring. For a given dairy farm implementing rotational grazing, a gradient in pasture biomass between paddocks will exist. A review of historical farm walk data from the Tasmanian Dairy Demonstration Farm and two commercial farms, showed that determining the gradient between the highest three and lowest three paddocks provided an adequate correlation with total farm pasture cover. Based on this historical analysis and feedback from farmer groups, a pasture farm cover estimator was developed. The tool has three simple viewing pages: 1. a data entry page where farm walk data is entered and a farm pasture cover estimate is provided; 2. a paddock management page where the individual paddocks are displayed and can be removed, added or edited; and 3. an historical page where data for each individual paddock or farm can be stored and viewed. This paper provides a comprehensive description of the farm pasture cover estimator and the underpinning historical analysis.