Comparison of Agrotain-treated and standard urea on an irrigated dairy pasture

Trials were started in spring, summer and autumn to compare the effect of Agrotain-treated urea and standard urea, at application rates of 25, 50, 75 and 100 kg N/ha, on dairy pasture production on a commercial dairy farm in Canterbury. There were six replicates of these eight treatments, plus two control plots per replicate where no urea was applied. Each trial was mown three times at around the second fully emerged leaf stage, and a subsample taken for dry matter determination. Yields generally increased with increasing rates of urea. There was no difference in pasture yield response between Agrotain-treated urea and standard urea in the wet conditions of the summer trial. In the dry conditions of the spring and autumn trials, Agrotain-treated urea produced 327 kg/ha more pasture dry matter than standard urea, although the yield advantage was small (130 kg/ha) at fertiliser application rates of 50 kg N/ha or less, compared to 524 kg/ha at 75 kg N/ha or more.