Calculating nitrogen leaching losses and critical nitrogen application rates in dairy pasture systems using a semi‐empirical model

Treating grazed pasture soil with a nitrification inhibitor, eco‐n™, to decrease nitrate leaching in a deep sandy soil under spray irrigation—a lysimeter study

“…However, the total annual NO 3 --N leaching loss under the urine patch from the present study (85 kg N ha -1 yr-1 ) was much smaller than that from the Lismore soil reported earlier (516 kg N ha -1 yr-1 ), largely because the Templeton soil used in the present study has a deeper soil profile and thus a greater water retention capacity compared with the Lismore soil (Di & Cameron 2002c). Because NO 3 -leached in a grazed pasture soil is derived predominantly from animal urine patches (Ledgard et al 1999;Silva et al 1999;Di & Cameron 2000,2002bDi et al 2002;Monaghan et al 2002), a significant reduction in NO 3 -leaching from the urine patches would effectively reduce the overall NO 3 -leaching losses from a grazed pasture system.…”

A lysimeter study of the fate of15N‐labelled nitrogen in cow urine with or without farm dairy effluent in a grazed dairy pasture soil under flood irrigation

“…For instance, if the stocking rate is 3 dairy cows ha -1 , the area covered by urine patches is c. 25% of the paddock per year. Therefore annual NO3 --N leaching losses from a grazed paddock should be calculated on the basis of the areas that are covered by urine and non-urine patch areas (Di & Cameron 2000). For instance, if the NO 3 --N leaching loss is 77 kg N ha -1 yr -1 from the urine patch areas and 1.5 kg N ha -1 yr -1 from the non-urine patch areas (Control, assuming no other N was applied) (Table 3), then the average NO3 --N leaching loss from the grazed paddock is estimated to be 20.4 kg N ha -1 yr -1 .…”

“…In intensively grazed dairy pasture systems, although the amount of NO3--N leached is affected by inputs of N fertilisers and organic waste effluents (Scholefield et al 1993;Di et al 1998aDi et al ,b, 1999Ledgard et al 1999a;Silva et al 1999;Monaghan et al 2000), the largest contribution comes from the N returned from the animal urine (Ball et al 1979;Ryden et al 1984;Field et al 1985;Silva et al 1999;Di & Cameron 2000, 2002b. In a grazed pasture, between 60-90% of the N ingested by the grazing animal is returned to the pasture in the urine and dung and more than 70% of the N returned is in the urine (Haynes & Williams 1993;Jarvis et al 1995).…”

A comparison of soil and environmental quality under organic and conventional farming systems in New Zealand

“…In the absence of data comparing organic farming systems and conventional systems in New Zealand we have used two recently published nutrient budget models, OVERSEER™ for P, K, and S (Ledgard et al 1999), and a more precise model, the nitrogen from leaching estimation (NLE) model (Di & Cameron 2000), for N leaching losses from dairy pasture systems.…”