Abstract:

The contents of NH4+-N, NO3--N and NO2--N in different use types of soil from the same valley were determined using flow injection analysis method (FIAstar 5000) and traditional methods (MgO extraction and diffusion method, phenoldisulfonic acid colorimetry method and copperized cadmium reduction method), respectively. The average value, the determined error, the recovery rate and standard deviation were compared between the two methods. The result shows that flow injection analysis method is more rapid than traditional method and has a good stability in the determination of NH4+-N and NO3--N in soil (RSD <5%, n=5). Flow injection analysis method is also comparable with the recovery rate 96.7~98.3% and 98.5~102.0%. However, the flow injection analyser is unstabler than phenoldisulfonic acid colorimetry method in determination of NO2--N in soil (RSD>6%, n=5), and the analysis results are generally lower than true value and need to carry out the necessary correction. Therefore, if we measure NH4+-N and NO3--N in large amount soil samples, using the flow injection analyser is feasible, but when measuring the NO2--N content, there is a significant error existed and need to be corrected.