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Résumé :
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The effect of nitrate and ammonium application (0, 50, 100 and 150 mg N kg(-1) soil) was studied in an incubation experiment. Four Belgian soils, selected for different soil characteristics, were used. The application of both nitrate and ammonium caused an increase of the NO and N2O emission. The NO production from nitrate and ammonium was found to be of the same order of magnitude. At low pH the NO production was found to be highest from nitrate, at higher pH values the production was found to be higher from ammonium. This seems to be the result of the negative effect of low pH on nitrification. The ANOVA analysis was carried out to separate the effect of the form of nitrogen, quantity of N applied and soil characteristics. The total production of NO was found to depend for 97% on the soil characteristics and for 3% on the quantity of N added. The total N2O production depended for 100% on the soil characteristics. Stepwise regression analysis showed that the total NO production was best predicted by a combination of the factors CaCO3 content and NH4+ concentration in the soil. Total N2O production was best described by a combination of CaCO3, water soluble carbon (WSC) and sand-content.
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