The fate of urine nitrogen: A grassland lysimeter study in Ireland

Abstract

In grazed pasture systems, the nitrogen (N) contained in a cattle urine patch may be up to 1200 kg N ha⁻¹. The majority of this N is in excess of plant requirements and is vulnerable to environmental loss. In this study, cattle urine was applied at five rates of nitrogen, 0, 300,500, 700 and 1000 kg N ⁻¹ soil monolith lysimeters in late autumn in Ireland. Measurements of gaseous N emissions, nitrate (NO₃⁻) leaching and pasture N uptake were made for a calendar year following urine application in two consecutive experiments. Increasing the rate of urine N applied increased the cumulative nitrous oxide (N₂O) emissions, NO₃⁻ leaching and pasture N uptake in years one and two, and the relationships were curvilinear with N recovery diminishing at the higher N rates.