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 increasingly important for agricultural food crop production in the country. However, on account of their strongly acidic properties, there is the need to apply agricultural lime to the soils to improve upon their productivity. At present, however, information on the lime requirement and appropriate liming practice for these soils is lacking. The objective of this study was to compare the suitability of selected chemical methods 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, exchangeable aluminum (Al), and Shoemaker, McLean, and Pratt (SMP) buffer methods. Correlation analysis showed that all the methods were highly correlated with one another. The SMP method was found to be somewhat better than either exchangeable Al or Ca(OH)2 titration method for estimating the lime requirement of the soils. Hence, the SMP method is recommended for use as the diagnostic index of lime requirement of these soils because of its speed and simplicity. Regression studies on the lime requirement values by the three methods and selected soil properties showed that exchangeable Al and organic carbon were the most important soil factors contributing to the lime requirement of these soils. Clay content was significantly correlated only with the Ca(OH)2‐based lime requirement values (r = 0.81*).