Status of B, Cu, Fe, Mo and Zn of soils of Ethiopia for maize production: greenhouse assessment

Greenhouse experiment using omission technique was conducted to evaluate the status of Fe, Cu, Zn, B and Mo in some Nitisols of Western Ethiopia and Rift Valley Andisols for maize production in order to confirm the results of the laboratory study. For each nutrient under study, a randomized complete block design with five treatments and four replications was employed. The treatments were: (1) control, no nutrient application, (2) application with low rates of all nutrients, (3) application with medium rates of all nutrients, (4) application with high rates of all nutrients, and (5) application with medium rates of all nutrients except the micronutrients under study. Considering the results of the present experiment and those in the previous laboratory assessment the following conclusions were drawn. Fe status of all of the Andisol was in the sufficient range whereas about 1.9 percent of the Nitisols was in the deficient range for maize production. The results of the present study did not support the critical level of 4.8 mg Fe/kg by AB-DTPA method reported by other authors. The results on of this experiment showed that the critical levels were lower than 4.56 mg Fe/kg in the case of Andisols and higher than 5.20 mg Fe/kg in the case of Nitisols. Cu status of all of the Andisols was in the deficient range whereas that of 5.6 percent of the Nitisols was in the deficient range for maize production. Zn status of all of the Nitisols was in the deficient range whereas that of all of the Andisols was in the sufficient range. B status of 31.9 percent of the Nitisols was in the deficient range whereas that of all of the Andisols was in the sufficient range. Mo status of all of the Andisols was in the sufficient range whereas that of 4.4 percent of the Nitisol was in the deficient range. The present results supported the critical levels for Cu, Zn, B and Mo found in the literature.