Relative Suitability of Phosphorus Extraction Procedures for F Tropical Ferralsol
J. S. Tenywa *
Department of Agricultural Production, College of Agricultural and Environmental Sciences, Makerere University, P.O.Box 7062, Kampala, Uganda.
E. Odama
Department of Agricultural Production, College of Agricultural and Environmental Sciences, Makerere University, P.O.Box 7062, Kampala, Uganda.
A. K. Amoding
Department of Agricultural Production, College of Agricultural and Environmental Sciences, Makerere University, P.O.Box 7062, Kampala, Uganda.
*Author to whom correspondence should be addressed.
Abstract
Purpose: To evaluate the predictive capacity common procedures for soil P extraction and testing in laboratories in the region.
Materials and Methods: A pot study with treatments viz. soil phosphorus extraction methods (Bray I, Bray II and Mehlich 3), and six P application rates (0, 20, 40, 60, 80 and 100 kg P ha-1). Maize (Zea mays L.) variety Longe IV was the test crop. A Ferralsol from northwestern Uganda (West Nile) was used in this study.
Results and Conclusion: Mehlich 3 correlated most with plant P uptake by presenting the highest correlation coefficient with plant P content (r = 0.254) and a number of leaves per plant (r = 0.733). A strong positive correlation existed between Bray I and Mehlich 3 extractable P values (r = 0.975), suggesting lack of a marked difference between them; implying that either of the two procedures could be applied for soil P extraction in Ferralsols. However, Mehlich 3, being a multi-nutrient extractant, was recommended as the most suitable for P extraction for the Ferralsol used in this study.
Keywords: Bray, extractant, Mehlich 3, Uganda, Zea mays