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Soil and Environmental Effects on Urease Inhibition by Ammonium Thiosulfate
Author(s) -
Sullivan D. M.,
Havlin J. L.
Publication year - 1992
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1992.03615995005600030044x
Subject(s) - chemistry , soil water , ammonia volatilization from urea , urea , thiosulfate , ammonium , urease , incubation , soil ph , fertilizer , environmental chemistry , hydrolysis , ammonium nitrate , ammonia , soil science , biochemistry , organic chemistry , sulfur , environmental science
Soil urease inhibition by ammonium thiosulfate [ATS, (NH 4 ) 2 S 2 O 3 12‐0‐0‐26S] in fluid fertilizer mixtures with urea‐ammonium nitrate (UAN, 32‐0‐0) has been demonstrated for a limited number of soils. The objectives of this study were to (i) identify soil properties affecting ATS efficacy, (ii) measure ATS effects on gaseous NH 3 losses, (iii) evaluate the effects of soil moisture and temperature on ATS efficacy, and (iv) measure the S species present after application of UAN + ATS. Urea hydrolysis inhibition by ATS ranged from 18 to 48% in eight Kansas soils varying in pH, clay, organic C, and carbonate content in an incubation at 20 °C and −0.1 MPa soil matric potential. Ammonia loss was significantly reduced in seven of the eight soils tested (48% in four noncalcareous soils and 22% in three calcareous soils). Urea‐hydrolysis inhibition averaged 29% at 20°C and 37% at 30°C; inhibition averaged 28% at −0.03 MPa and 38% at −0.1 MPa. Tetrathionate (S 4 O 2‐ 6 ) was the dominant S anion produced by S 2 O 3 2‐ oxidation, ranging from 17 to 88% of the applied S. The amount of S 4 O 2‐ 6 present was not significantly correlated with the degree of ureahydrolysis inhibition. Ammonium thiosulfate inhibited urea hydrolysis in all soils; its efficacy was greatest for soils low in clay and organic C at high temperatures and low soil moisture contents.