A METHOD FOR DIRECT MEASUREMENT OF 15N-GASES FROM NITRIFICATION-DENITRIFICATION WITH MASS SPECTROMETER

Reliability of the method developed in the laboratory for direct measurement of (N2+N2O+NOx)-15N from nitrification-denitrification was examined in the present paper. The results showed that the amount of (N22+N2O+NOx)-15N produced thuough denitrification of added 15N-nitrate by the two methods (15N enrichment of the NO3-N pool undergoing denitrification, and 15N enrichment of the gas samples) were measured accurately; the recovery of added 15N-nitrate as (N2+N2O+NOx)-15N from denitrification was up to 94. 1% in the flooded incubation experiment. The error of the method was increased with decrease in 15N enrichment of gas samples. It is concluded that the method is reliably. Therefore, investigation on nitrification-denitrification loss of fertilizer nitrogen can be done by using the method.