Spatially and temporally variable urinary N loads deposited by lactating cows on a grazing system dairy farm.

Feed nitrogen (N) intakes in Australian grazing systems average 545 g cow day, indicating that urinary N is likely to be the dominant form excreted. Grazing animals spend disproportionate amounts of time in places on dairy farms where N accumulation is likely to occur. We attached to grazing cows sensors that measure urine volume and N concentration, as well as global positioning systems sensors used to monitor the times the cows spent in different places on a farm and the location of urination events.