When urine and fertiliser were deposited concurrently prior towinter drainage, the fertiliser-N made a negligible contribution tothe total inorganic-N leaching pool with <2.17% of the 15N appliedas fertiliser recovered in the leachate after 554 days. These resultsconflict with the commonly held belief that fertiliser applied over aurine patch will simply exacerbate the fertiliser’s contribution tothe NO3-N leaching load because the N supplied from the urine patch is already surplus to the pasture’s N requirements. Wetherefore disprove the first hypothesis that, increased fertiliserassociated leaching would occur under urine patches withincreasing rates of fertiliser applied. However, it is important tonote that at the highest annual N application rate of 400 kg Nha1,which is double the recommended best practice rate, split Nfertiliser applications on top of a urine patch increased the totalNO3 leaching loss (i.e. from non-fertiliser N sources). Weconfirmed the second hypothesis, that leaching would be greatestunder an autumn deposited urine patch when compared to aspring deposited urine patch. The results of this study indicate thatbest practice fertiliser management (i.e. fertiliser applied at<200 kg Nha1 year1) is environmentally benign under thecurrent experimental conditions, even in a wetter than averageyear.
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