HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Phillips, R. E. Articles by Patrick, W. H. Search for Related Content PubMed Articles by Phillips, R. E. Articles by Patrick, W. H., Jr. Agricola Articles by Phillips, R. E. Articles by Patrick, W. H.

The Role of Nitrate Diffusion in Determining the Order and Rate of Denitrification in Flooded Soil: II. Theoretical Analysis and Interpretation¹

ABSTRACT

A theoretical analysis of denitrification occurring in submerged soil in a test tube, when assumed to be a zero-order reaction with available organic carbon nonlimiting, appears to be a first-order reaction if the effects of diffusion are neglected. In this case, denitrification appears to be a first-order reaction because denitrification occurs at a faster rate than the diffusive flux can supply NO₃^--N to the soil. After some length of time, the concentration of NO₃^--N in the lower portion of the flood-water-soil interface will be equal to the concentration in the flood-water. After which time, denitrification occurs only in the upper portion of the soil sample. When the role of diffusion is neglected, it is generally assumed that denitrification occurs uniformly throughout the soil sample. It is for this reason that denitrification can appear to be a first-order reaction when it may actually be a zero-order reaction. The true order of reaction and rate constant of denitrification in a test tube can be evaluated experimentally by eliminating the floodwater above the soil sample; with this experimental geometry some of the confounding effects of diffusion of NO₃^--N can be minimized. If diffusion is neglected, not only is the order of reaction misjudged but the depth of floodwater above the soil has a significant effect on the magnitude of the calculated rate constant of the apparent first-order reaction also.

¹ Contribution from the Kentucky Agric. Exp. Stn. as Journal Article no. (77-3-26) and from the Louisiana Agric. Exp. Stn. and is published with the approval of the Directors.

² Professor of Agronomy, Univ. of Kentucky, Lexington, KY 40506 and Post-Doctoral Research Associate and Professor, Agronomy Dep. Louisiana State Univ., Baton Rouge, LA 70803.

Received for publication February 28, 1977. Accepted for publication November 7, 1977.