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 Kirkham, D. Articles by Bartholomew, W. V. Search for Related Content PubMed Articles by Kirkham, D. Articles by Bartholomew, W. V. Agricola Articles by Kirkham, D. Articles by Bartholomew, W. V.

Equations for Following Nutrient Transformations in Soil, Utilizing Tracer Data¹

ABSTRACT

Theoretical equations are derived, for utilization of tracer data, for determining rates of mineralization m and immobilization i of plant nutrients in soil. The equations for a particular nutrient are
where m = mass of immobile atoms mineralized per unit time per unit mass of soil (mineralization rate); i = mass of mineral atoms immobilized per unit time per unit mass of soil (immobilization rate); H₀ = mass of tracing (heavy, or radioactive) mineral atoms per unit mass of soil at time t = O; M₀ = mass of tracing, plus non-tracing mineral atoms per unit mass of soil at time t = O; H = mass of tracing mineral atoms per unit mass of soil at time t = t; M = mass of tracing, plus non-tracing mineral atoms per unit mass of soil at time t = t; t = time lapsed between measurements for H₀, M₀ and H, M; log = logarithm to base e or to base 10 for the equations for i m and to base e for the equation for m = i; e = 2.718.

The equations for m and i, and some others which are also given, are all only valid if M₀ and M are small compared to the amount of material which is being mineralized; and if i and m are constant during time t. The equations are applied to some nitrogen transformation data, with heavy nitrogen as the tracing element. The equations may also find application in studies of phosphorus and potassium fixation and release, with radioactive materials as the tracing elements. For numerical work, equations [a] and [b], although correct, should be replaced by equations [10] and [11] in the text if m > i.

¹ Journal Paper No. J-2337, of the Iowa Agr. Exp. Sta., Ames. Projects 998 and 1070.

² Professor Soils and Physics, and Associate Professor of Soils, respectively.

Received for publication May 29, 1953.