An evaluation of several soil tests for predicting wheat yield response to superphosphate in Victoria

Abstract

The predictability of three different measures of wheat yield response to superphosphate from each of four soil test measures of available phosphorus (0-6 inches) was examined, using data from field experiments over the period 1951 to 1965. The associations were studied separately within the three great soil groups that are dominant over the wheatgrowing areas of Victoria. Whichever measure of yield response was considered, soil bicarbonate P test measurement gave the best basis for prediction. However, at most, only 26 per cent of the yield response variability was predictable, and the other three tests were substantially less successful. Under the general conditions considered, where yield response is subject to a variety of uncorrected environmental deficiencies, it is concluded that the soil tests for P investigated in this paper are of doubtful practical value.