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Release of Nitrogen from Ureaform Fractions as Influenced by Soil pH
Author(s) -
Tlustos P.,
Blackmer A. M.
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/sssaj1992.03615995005600060026x
Subject(s) - soil water , chemistry , leaching (pedology) , nitrogen , mineralization (soil science) , water soluble , urea , environmental chemistry , soil science , environmental science , biochemistry , organic chemistry
Ureaforms are slow‐release N fertilizers that have potential for minimizing problems associated with leaching of NO ‐ 3 from soils and accumulations of NO ‐ 3 in vegetable crops. We studied the effects of soil pH on rates of release of N from various ureaform fractions. Three fractions (soluble in cold water, insoluble in hot water, and soluble in hot water but insoluble in cold water) were separated from a 15 N‐labeled ureaform, and mineralization of N from these fractions and from labeled urea was studied in six soils having pH values ranging from 5.2 to 7.8. The results showed that rates of inorganic N (NH + 4 and NO ‐ 3 ) release were extremely pH dependent; they varied > 100‐fold for the cold‐water‐insoluble fractions. The cold‐water‐insoluble fractions were largely responsible for slow release of N in acid soils, but these fractions and much of the cold‐water‐soluble fractions were essentially inert in soils above neutrality. The results suggest that successful use of ureaform fertilizers would require modifications in rates of application or composition of the ureaform to adjust for differences in soil pH.