COMPARATIVE-STUDY OF SELECTED LIME REQUIREMENT METHODS FOR SOME ACID GHANAIAN SOILS

The acid soils of the western region of Ghana which hitherto have been relegated to forest and tree crops production are becoming increasing ly important for agricultural food crop production in the country. How ever, on account of their strongly acidic properties, there is the nee d to apply agricultural lime to the soils to improve upon their produc tivity. At present, however, information on the lime requirement and a ppropriate liming practice for these soils is lacking. The objective o f this study was to compare the suitability of selected chemical metho ds for the determination of the lime requirement to predict lime needs of these naturally occurring acid soils. The lime requirement of six acid soils were determined by calcium hydroxide [Ca(OH)2] titration, e xchangeable aluminum (Al), and Shoemaker, McLean, and Pratt (SMP) buff er methods. Correlation analysis showed that all the methods were high ly correlated with one another. The SMP method was found to be somewha t better than either exchangeable Al or Ca(OH)2 titration method for e stimating the lime requirement of the soils. Hence, the SMP method is recommended for use as the diagnostic index of lime requirement of the se soils because of its speed and simplicity. Regression studies on th e lime requirement values by the three methods and selected soil prope rties showed that exchangeable Al and organic carbon were the most imp ortant soil factors contributing to the lime requirement of these soil s. Clay content was significantly correlated only with the Ca(OH)2-bas ed lime requirement values (r = 0.81).