The Effects of Soil Conditions and Nitrogen form on N2O Evolution by Denitrification

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Abstract
Nitrous oxide evolution from the soils treated with nitrogen fertilizer such as ammonium sulfate or sodium nitrate under different environmental conditions was measured by the combined method of gas chromatography and emission spectrometry (GC-ES). When NH4 + was added, two evolution peaks of N2O were detected. Eighty to 94% of the first peak was derived from endogenous soil nitrogen and about 75% of the second peak was derived from added fertilizer nitrogen. When NO3 − was added, there appeared only one peak, which was derived mostly (92–97%) from fertilizer nitrogen. The quantity of N2O evolved varied widely according to the kind of fertilizer, soil moisture content and content of easily decomposable organic matter of soil. The maximum amount of N2O evolved during a period of 23 days was 19.5% in the soil to which nitrogen had been applied as NO3 −, for a supply of 0.1% glucose per dry soil and water depleted-treatment. The minimum amount was 0.005% in the soil which received fertilizer as NH4 + for a supply of 1.0% glucose in the water-saturated treatment.