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Influence of Simulated Fall and Spring Conditions on the Soil System: II. Effect on Soil Nitrogen
Author(s) -
Campbell C. A.,
Biederbeck V. O.,
Warder F. G.
Publication year - 1971
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/sssaj1971.03615995003500030041x
Subject(s) - incubation , chemistry , loam , nitrification , soil water , nitrous oxide , nitrogen , moisture , environmental chemistry , sterilization (economics) , zoology , soil science , environmental science , biochemistry , biology , foreign exchange , organic chemistry , monetary economics , economics , foreign exchange market
Stored and fresh Wood Mountain loam samples were wetted to 20% moisture using either water, Ca(NO 3 ) 2 , or (NH 4 ) 2 SO 4 solutions. Half of the samples were sterilized with ethylene oxide. Fall conditions were imposed by incubating samples at diurual temperatures of 14 to 3C and early spring conditions by slow freezing to −23C followed by incubation at 14 to 3C or 8.5C. Exchangeable NH 4 ‐N, NO 3 ‐N, and microbial counts were determined at appropriate intervals. In the unamended and NO 3 ‐amended soils, freezing followed by 16 days incubation at 14 to 3C had a bactericidal effect and resulted in a much lower rate of nitrification than freezing followed by incubation at 8.5C. Where NH 4 had been added the bactericidal effect was not as great and there was no difference in nitrification between the two incubation temperatures. Incubation at low temperatures impeded nitrification more than ammonification which resulted in an initial buildup of exchangeable NH 4 . Ethylene oxide was an effective soil sterilant but caused a small increase in the exchangeable NH 4 . Freezing followed by incubation at low temperatures increased the exchangeable NH 4 in sterile soils but did not affect the NO 3 content. There was evidence of an interaction between the length of soil storage and the various treatments (viz, freezing, sterilization , etc.).