Nitrate leaching losses from lysimeters simulating winter grazing of fodder beet by dairy cows

Abstract

ABSTRACTNitrate-N (NO3−-N) leaching losses from dairy cow urine and non-urine areas of simulated winter grazing of fodder beet (Beta vulgaris L.) were quantified using large intact soil monolith lysimeters (50 cm diameter × 70 cm depth), containing Balmoral/Lismore stony silt loam soil. Fresh cow urine was applied to half of the lysimeters in mid- to late-June at 300 kg N ha−1 in 2012 and 250 kg N ha−1 in 2013, following simulated fodder beet grazing. The remaining half did not receive urine to represent non-urine areas of a grazed paddock. Most of the N leached was from the urine-treated lysimeters and 92%–98% was in the form of NO3−-N. Total NO3−-N leached from the urine-treated lysimeters represented an equivalent of 21% (64 kg NO3−-N ha−1) and 32% (84 kg NO3−-N ha−1) of the total urine-N applied in 2012 and 2013, respectively. Nitrate-N leaching losses from lysimeters receiving no urine were between 10 and 11 kg NO3−-N ha−1.