Duration-controlled grazing of dairy cows. 2: nitrogen losses in sub-surface drainage water and surface runoff.

The annual quantities of nitrate-N (-N) and total N (TN) leached from mole and pipe drained dairy pastures on a Pallic soil, were reduced by an average of 52% and 42% (p < .05), respectively, by standing cows off pasture to ruminate and rest after grazing (Duration-controlled grazing, DC), compared to the standard grazing management (SG) of leaving cows at pasture between milkings. For the SG treatment, measured -N leached was 13, 8 and 21 kg N ha⁻¹ and total N leached was 18, 13 and 26 kg N ha⁻¹ in 2009, 2010 and 2011, respectively. Annual surface runoff contained <1 kg -N ha⁻¹ y⁻¹ and <3 kg TN ha⁻¹ y⁻¹. The deposition of urine in the autumn period had the greatest influence on the quantity of leached in winter drainage. DC grazing is a practical method to reduce N leaching from grazed dairy pastures. [ABSTRACT FROM AUTHOR]