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

Abstract

ABSTRACT Nitrate‐N (NO 3 − ‐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 NO 3 − ‐N. Total NO 3 − ‐N leached from the urine‐treated lysimeters represented an equivalent of 21% (64 kg NO 3 − ‐N ha −1 ) and 32% (84 kg NO 3 − ‐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 NO 3 − ‐N ha −1 .