The objective of this investigation was to correlate plant growth response with chemically measured available phosphorus in the soil.Eight chemical methods of extracting the available phosphorus in the soil samples were utilized. An attempt was made to correlate growth response of wheat with chemically measured available phosphorus. The principles of Mitscherlich as modified by Bray were employed.In general, the amount of chemically measured phosphorus as extracted by the Spurway active extracting solution was quite low in comparison to that extracted by the other methods, all of which contained some hydrochloric acid. Increasing the time of shaking during extraction or increasing the ratio of extracting solution to soil did not improve the Spurway active test.The use of any of the methods of Bray provided a considerably clearer picture of phosphorus availability because the inclusion of fluoride in the extracting solution enabled the adsorbed phosphorus in the soil to be removed. Apparently this removal was essential in measuring chemically available phosphorus. An extracting ratio of one part of soil to 50 parts of solution was more desirable for adsorbed phosphorus studies than the narrow ratio of one part of soil to 10 parts of solution.The two methods of Spurway were apparently of about the same suitability and as such were poorer than any of the methods advocated by Bray and his associates. The use of either the customary method of Bray for measuring total available phosphorus or adsorbed phosphorus at an extraction ratio of 1:10 gave comparable results. Increasing the extraction ratio of 1:50 did not improve the method of measuring total available phosphorus as evidence by correlation with plant yield response. However, increasing the ratio to 1:50 for the adsorbed phosphorus extraction did result in a notable improvement and also resulted in the best single method employed under the conditions of this investigation.