Urine patch size and nitrogen load: effects on nitrogen uptake from the urine patch in plantain and ryegrass/white clover pastures

Field measurements from micro-plots of ryegrass/white clover and of plantain to mimic a urine patch (UPs) were used to test the effects of UP nitrogen (N) load and size on pasture N uptake. Most (>90%) of the apparent uptake of urine N by plantain and standard pastures was within 20 cm of the edge of the UP. For the two urine patch sizes tested in the field (0.2 and 0.36 m2), edge contribution to urine N uptake was on average c. 30% of the total from the UP, but was higher for at 600 kg N/ha urine N (45%) than at 300 kg N/ha (18%). Understanding this edge contribution is important for model improvement, and for the development of mitigations to decrease N leaching.