Soil micronutrient contents and relation to other soil properties in Ethiopia

Alfisols, Vertisols, Inceptisols, Aridisols, Mollisols, and Entisols were s ampled (0-30 cm) from 32 locations across Ethiopia. The soils were analyzed for copper (Cu), zinc (Zn), manganese (Mn), and iron (Fe) contents using 0 .005 M diethylene triamine pentaacetic acid (DTPA), 0.05 M hydrochloric aci d (HCl), and 0.02 M ethylene diamine tetraacetic acid (EDTA) extractants. E DTA extracted more of each micronutrient than DTPA, which extracted greater amounts than HCl. The quantities of EDTA and DTPA-extractable micronutrien ts were significantly correlated, and were in the order: Mn>Fe>Cu>Zn. The o rder of HCl-extractable micronutrients was Mn>Fe>Zn>Cu. Micronutrient conte nts of Mollisols, Vertisols, and Alfisols were usually greater than those o f the other soils, and Entisols usually had the lowest micronutrient conten ts. The contents were mostly positively correlated with clay and Fe2O3 cont ents, but negatively correlated with soil pH and Al2O3 contents. While comp arison of DTPA- and EDTA-extractable micronutrients with critical levels sh owed that most soils had adequate amounts of the micronutrients for crops, the amounts extracted by HCl were below critical levels in most soils. Sinc e the critical levels that were used in the comparisons were not establishe d in Ethiopia, calibration of the soil contents of these micronutrients wit h crops grown in Ethiopia is required to identify the most suitable extract ant(s).