Fate of Urine Nitrogen in Three Soils throughout a Grazing Season

• Published in: Journal of environmental quality Vol. 32; no. 4; pp. 1405 - 1413
• Main Authors: Decau, M.L, Simon, J.C, Jacquet, A
• Format: Journal Article
• Language: English
• Published: Madison American Society of Agronomy, Crop Science Society of America, Soil Science Society 01.07.2003; American Society of Agronomy; Crop Science Society of America
• Subjects: Animals; Cattle; Climatic conditions; Environmental Monitoring; Environmental Sciences; Grazing; Leaching; Life Sciences; Lolium - chemistry; Lysimeters; Nitrates - analysis; Nitrogen; Nitrogen - analysis; Nitrogen - pharmacokinetics; Organic matter; Pasture; Plant Roots; Plants, Edible; Seasons; Silt loam; Soil; Soil organic matter; Soil Pollutants - analysis; Soil types; Urine; Urine - chemistry; Water content; Water Movements; Water Pollutants - analysis; ABSORPTION DE L'AZOTE
• ISSN: 0047-2425; 1537-2537
• DOI: 10.2134/jeq2003.1405

The fate of 15N-labeled cattle (Bos taurus) urine (52 g N m−2), applied to a 0.4-m2 surface area on three dates between May and October to three different pasture soils, was studied using 2-m2 lysimeters. Over a period of two years, the sward recovered most of the 15N, but the amount recovered decreased with application date (62% in spring to 17% in fall). However, N uptake by ryegrass (Lolium perenne L.) in Year 2 showed that some nitrogen came from the previous year's urine application. The largest leaching losses of urine N resulted from the late application date. These losses mainly occurred during the first winter despite the small amount of water drainage. Soil type largely determined 15N losses. The granitic Brunisol was the most freely draining and had the greatest leaching (up to 35% recovery of urinary N). In contrast, leaching in the silty loam Neoluvisol remained under 4% of 15N applied. The Calcosol appeared to be susceptible to all kinds of N losses with intermediate unaccounted-for N pool and leaching fractions and lesser utilization of urinary N by grass. Immobilization in soil organic matter, roots and litter, and stubble pools were not markedly influenced by the date of application or soil type. They amounted to 25 to 33, 2, and 2% of N applied as urine, respectively. In these climatic conditions with moderate drainage, leaching of water poor in quality for nitrate only occurred for late-season grazing or on the granitic Brunisol, which was very vulnerable to leaching.