Effect of timing of cattle urine deposition and pasture composition on nitrogen leaching losses

Abstract

A lysimeter experiment using undisturbed monoliths from a stony silt loam soil was carried out to quantify the effects different pasture types on N losses from urine applied to soil on different dates. Three pasture types were tested: (a) perennial ryegrass (Lolium perenne)/white clover (Trifolium repens) (PRG/WC), (b) perennial ryegrass/white clover/plantain (Plantago lanceolata) (PRG/WC/P) and (c) Italian ryegrass (Lolium multiforum)/white clover/plantain (IRG/WC/P), with four different urine applications dates (late summer, early autumn, mid-autumn and late autumn). Cattle urine was applied at the equivalent of 700 kg N¯¹ ha¯¹. There was a significant reduction in total amount of nitrate (NO₃¯-N) leached under the PRG/WC/P (14% reduction) and IRG/WC/P (24% reduction) compared with the PRG/WC. High NO₃¯-N leaching losses were found at each urine application date (>181 kg NO₃¯-N/ha), suggesting there may be higher than expected N leaching losses when urine is deposited onto shallow stony soils, during warmer months (late summer and early autumn). There was no significant interaction between pasture type and urine timing on NO₃¯-N leaching losses.