Micronutrients are important for crop growth, production and their deficiency and toxicity affect crop yield. However, the up dated information about their status and spatial distribution in Ethiopian soils is scarce. Therefore, fertilizer recommendation for crops in the country has until recently focused on nitrogen and phosphorus macronutrients only. But many studies have revealed the deficiency of some micronutrients in soils of different parts of Ethiopia. To narrow this gap, this study was conducted in Kedida Gamela, Kecha Bira and Damboya districts of Kambata Tambaro (KT) Zone, Southern Ethiopia, through assessing and mapping the status and spatial distribution of micronutrients. The micronutrients were extracted by using Mehlich-III multi-nutrient extraction method and their concentrations were measured by using Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES). The fertility maps and predication were prepared by co-Kriging method using Arc map 10.0 tools and the status of Melich-III extractable iron (Fe), Zinc (Zn), boron (B), copper (Cu) and molybdenum (Mo) were indicated on the map. The extracted Fe ranged from 50.04 to 209.72 mg/kg, 60.08 to 240 mg/kg and 46.84 to 412.23 mg/kg in Kedida Gamela, Kecha Bira and Damboya districts soils, respectively. Zn ranged from 1.3 to 28 mg/kg, 0.9 to 47 mg/kg and 1.0 to 39 mg/kg for Kedida Gamela, Kecha Bira and Damboya districts, respectively. The calculated manganese activity index (MnAI) indicated that Mn is in excess and even toxic. B ranged from 0.02 to 1.83 mg/kg, 0.4 to 1.44 mg/kg and 0.06 to 2.03 mg/kg in soils of Kedida Gamela, Kecha Bira and Damboya woredas, respectively indicating that most of soils were deficient in B. Cu ranged from 0.6 to 2.9 mg/kg, 0.5-1.44 mg/kg and 0.8 to 3.4 mg/kg in Kedida Gamela, Kecha Bira and Damboya districts indicating its status fall between low and optimum category. Mo ranged from 2.21 to 18.71 mg/kg in the soils of the study area indicating that all soils were sufficient in Mo content. The means of all micronutrients except B showed significant differences among districts and showed moderate spatial dependences. The range of semivariogram for all studied micronutrients was greater than the average sampling distance indicating that it was adequate enough to catch spatial variability of them. In order to strengthen this result, plant sample analysis and calibration of micronutrients with plant response are recommended.
Key words: Boron, Copper, Iron, Kriging, Manganese, Mehlich-III, Molybdenum, Zinc and spatial dependency.