Soil extractable organic sulfur and sulfate increases under dairy cow feces and urine patches: The consequences for soil testing

• Published in: Communications in soil science and plant analysis 2003-01, Vol.34 (1-2), p.189-199
• Main Authors: Kear, M.J, Watkinson, J.H
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; cattle manure; Chemical, physicochemical, biochemical and biological properties; dairy cows; defecation; Fundamental and applied biological sciences. Psychology; grassland soils; Mineral components. Ionic and exchange properties; organic sulfur compounds; pastures; Physics, chemistry, biochemistry and biology of agricultural and forest soils; soil analysis; soil nutrients; soil organic matter; Soil science; spatial variation; sulfates; urination; urine
• ISSN: 0010-3624; 1532-2416
• DOI: 10.1081/CSS-120017425

The usual method to determine the sulfur (S) status of soil in a grazed pasture system is to measure extractable soil sulfate. Plants annually uptake more S than is present as soil sulfate. Additional S comes from rainfall, fertilizer, excreta, or mineralization of soil organic S. The amount of soil organic S available for mineralization is measured by the amount of extractable soil organic S in 0.02 M KH 2 PO 4 (the 'organic S test'). Organic S comprised 67% of total S in fresh dairy cow urine and 84% of total S in feces. Feces and urine patches from grazing dairy cows are a potential source of error in the soil testing for sulfate and organic S. Recovery of organic S from soil beneath feces and urine patches was much lower than sulfate. Our results show that the organic S soil test was little influenced by soil sampling under dung and urine patches.