Evaluation of Nitrogen‐15 Tracer Techniques for Direct Measurement of Denitrification in Soil: II. Simulation Studies

Abstract

Abstract In mass spectrometric procedures developed at the University of Illinois for determination of 15 N‐labeled dinitrogen (N 2 ) and nitrous oxide (N 2 O) evolved from soils, the assumption is made that the nitrate (NO − 3 ) undergoing denitrification exists in a single pool that is isotopically uniform. Computer simulation studies were conducted to identify trends associated with errors in measuring denitrification of NO − 3 that exists in two or more pools having different enrichments. The results indicate that, for a constant mean 15 N enrichment, the magnitude of the error increases as the range of enrichment becomes greater and can increase or decrease with increase in the number of NO − 3 pools, depending upon whether there is an increase in the range of enrichment. The error is also affected by the extent to which evolution is distributed among the various pools, but it does not depend upon the overall evolution rate or the 15 N enrichment of the fertilizer applied.