The fate of urine nitrogen with use of a nitrification inhibitor

Abstract

Pasture-grazed ruminants in Ireland contribute a significant proportion of nitrogen (N) loss to the environment through excreta deposition. Feed N utilisation by the ruminant animal is low with 60-90% of ingested N returned to the soil/pasture system in the excreta, particularly in the urine (Haynes and Williams, 1993). The urine N loading rate in a single cattle urine patch is approximately 1000 kg N ha⁻¹ (Haynes and Williams, 1993). N balance studies have estimated the fate of urine N on a range of soils (Clough et al., 1998). Application of dicyandiamide (DCD) nitrification inhibitor has consistently reduced N leaching and N2O emissions from urine patches (Di and Cameron,2007; de Klein et al., 2011), but produced variable pasture N responses (Di and Cameron, 2007; Zaman and Blennerhassett, 2010). A ¹⁵N balance study was conducted on grassland lysimeters in Ireland to investigate the fate of urine N with and without the application of DCD nitrification inhibitor.