Advisory Soil or Plant Analysis and Fertilizer Use I-Comparison of Soil Analysis is Methods

Abstract

One hundred and twenty-four topsoil samples representing 16 different soil types, of which seven had pH values greater than 7.0, have been analysed for extractable phosphorus, potassium, calcium and magnesium by four different methods. The degree of correlation between the methods is presented together with linear regression equations. Within the range of soil type and analytical data encountered it is possible to convert direct analytical values into predicted values by alternative methods of analysis. Extractable phosphorus, potassium, calcium and magnesium values are predictable for acid/-neutral soils, but it would be more reliable to use separate calibration data or more suitable analytical methods for alkaline pH soils. The larger proportion of phosphorus results in these samples were in the lower half of the full range encountered and the prediction equations are duly biased.