Reduction de l'oxyde nitreux dans les sols de rizieres du senegal: Mesure de l'activite denitrifiante

A new method to estimate the rate of denitrification in soil was developed, and two different activities were measured: (1) the initial (or true) denitrifying activity of the soil under prevailing conditions; (2) the potential denitrifying activity induced by the addition of N₂O. Less than 50 g of soil, saturated with water, were incubated anaerobically at 37°C, with a known amount of N₂O, and the disappearance of N₂O was followed by gas chromatography. In 25 paddy soils of Senegal, a highly positive rank correlation was found to exist between the denitrifying activity measured by chromatographic and respirometric methods, under the same conditions of incubation with either N₂O or NO₃^? as the hydrogen acceptor. By the N₂O reduction method, it was found that there was no initial denitrifying activity in the rhizosphere of 3-week-old rice.