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

This Article Full Text (PDF) An erratum has been published An erratum has been published Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (53) Citing Articles via Google Scholar Google Scholar Articles by Mackay, A. D. Articles by Gregg, P. E. H. Search for Related Content PubMed Articles by Mackay, A. D. Articles by Gregg, P. E. H. Agricola Articles by Mackay, A. D. Articles by Gregg, P. E. H.

A Simple Model to Describe the Dissolution of Phosphate Rock in Soils¹

ABSTRACT

Dissolution of phosphate rock (PR) in contrasting soils was evaluated by extraction with 0.5 M NaOH following a prewash with 1 M NaCl to remove exchangeable Ca²⁺. This provides a simple and direct method for measuring the rate and extent of PR dissolution in soils. Dissolution of Sechura phosphate rock (SPR) in six soils was essentially complete at 90 d and the pattern of dissolution could be described by a modified Mitscherlich equation of the form y = A (1 – e^-ex), in which y = amount of SPR dissolved at time x; A = asymptote, and c = curvature coefficient. Whereas A varied markedly across soils, c was independent of soil type. This exponential equation formed the basis of a simple model which describes and predicts the dissolution of SPR in soils. By establishing the relationship between A and a range of properties for 30 contrasting soils it was possible to identify those soil parameters that controlled PR dissolution in soil. Percent Ca-saturation, P-sorption capacity, and Ca-exchange capacity of the soil were the three most important parameters influencing SPR dissolution in soils. When a model incorporating these three parameters was tested on soils not used to construct the model, the variance accounted for ranged from 66 to 76%, depending on the population of soils selected. These parameters determine the concentrations of Ca²⁺ and H₂PO^-₄ in the soil solution.

¹ Research supported by the Fertilizer and Lime Research Centre and the Massey Univ. Agricultural Research Foundation, Massey Univ., Palmerston North, New Zealand.

² Former Postgraduate Research Assistant, now at Grasslands Div., Dep. of Scientific and Industrial Research, Private Bag, Palmerston North; Professor, Senior Research Officer, and Reader, respectively, Dep. of Soil Science, Massey Univ., Palmerston North, New Zealand.

Received for publication March 22, 1985.

This article has been cited by other articles:

				S. Yampracha, T. Attanandana, A. Sidibe-Diarra, and R. S. Yost Predicting the Dissolution of Rock Phosphates in Flooded Acid Sulfate Soils Soil Sci. Soc. Am. J., October 27, 2005; 69(6): 2000 - 2011. [Abstract] [Full Text] [PDF]

				M. Shenker and P. R. Bloom Comments on "Amounts, Forms, and Solubility of Phosphorus in Soils Receiving Manure" Soil Sci. Soc. Am. J., June 28, 2005; 69(4): 1353 - 1354. [Full Text] [PDF]