Urine patch area coverage of an intensively stocked dairy pasture

Abstract

The urine patch of the grazing cow has been identified as the key source of N loss from pasture-based dairy systems. Although critical to N modelling, quantitative data on the annual area coverage of urine patches in pastures is scarce. A new technique using survey-grade global positioning system (GPS) technology was developed to measure the paddock area coverage of dairy cattle urine and dung patches. A four year study was conducted on an intensively stocked (4.3 cows/ha) dairy farm in Canterbury, New Zealand. Twelve field plots on typical grazed pasture were monitored over a four year period, sampling at 12 week intervals. Urine and dung deposits within the plots were visually identified, the pasture response area (radius) measured and position marked with survey-grade GPS. Spatial geographic information system (GIS) software was used to analyse the data. The mean urine patch pasture response area was 0.35 m². It was calculated that the mean area covered by urine patches on an annual basis was 23.1 ± 2.2 % for the given stocking density and grazing management regime.