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 Peaslee, D. E. Articles by Black, C. A. Search for Related Content PubMed Articles by Peaslee, D. E. Articles by Black, C. A. Agricola Articles by Peaslee, D. E. Articles by Black, C. A.

Estimation of Relative Value of Phosphate Rock and Superphosphate to Plants on Different Soils¹

ABSTRACT

The relative value of phosphate rock and superphosphate as sources of P for plants was evaluated by a test crop of sorghum on 19 soils in greenhouse cultures. The results were expressed as availability-coefficient ratios. In the laboratory, three sets of measurements were made of P extractable from untreated soil, phosphate-rock-treated soil, and superphosphate-treated soil: (1) P extracted by 0.025N HCl, 0.03N NH₄F solution used in a ratio of 1 part of soil to 50 of solution by weight (method of Bray and Kurtz modified by Smith and Grava) after a 30-day incubation period, (2) P extracted by an anion-exchange resin without prior incubation, and (3) P extracted by an anion-exchange resin after incubation for 30 days. Methods 2 and 3 were modifications of the method of Amer et al. The results were expressed as extractability-coefficient ratios. The correlation between availability-coefficient ratios and extractability-coefficient ratios was highest with method 2 and lowest with method 1. The correlation between soil pH values and availability-coefficient ratios was equally as close as that obtained between availability-coefficient ratios and extractability-coefficient ratios by method 2.

¹ Journal Paper No. J-4277 of the Iowa Agr. and Home Econ. Exp. Sta., Ames. Project No. 1183. Contribution from the Department of Agronomy. Presented before Div. IV, Soil Science Society of America, Nov. 30, 1961, at St. Louis, Mo.

² Graduate Assistants and Professor of Soils, respectively. The senior author is now Assistant Soil Scientist at the Connecticut Agr. Exp. Sta., New Haven.

Received for publication February 16, 1962. Accepted for publication April 30, 1962.