Soil Properties Affecting Formation of Nitric Oxide by Chemical Reactions of Nitrite

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Abstract
Gas chromatography was used to determine the amounts of nitric oxide (NO) in the headspaces above samples of 28 soils that had been autoclaved, treated with nitrite, and sealed in all‐glass flasks with He atmospheres for 18 h. When nitrite was added at a rate of 100 mg N kg−1 soil, the amounts of NO‐N found ranged from less than 1 to 35 mg kg−1 soil, and statistical analyses indicated that 95% of the variability in the amounts of NO found among the soils could be explained by a model that considered only soil organic C content, pH, and an interaction of these factors. The formation of CO2 and the ratios of NO to NO‐3 observed indicate that production of NO cannot be explained solely by self‐decomposition of nitrous acid. When various amounts of soil were added to identical samples of nitrite solution, the amounts of NO‐N found increased with amounts of soil added. These findings indicate that NO is formed by reactions of nitrite with the organic fraction of soils as well as by self‐decomposition of nitrous acid.