Assessment and Geospatial Mapping of Soil-micronutrients: Case Study from a Micro-watershed of Semi-arid Tropics in Southern India

Available micronutrient status in the soil of Chotanahalli micro-watershed (468 ha) in Kunigal Taluk, Tumkur district was studied and mapped using geospatial technique. Forty three surface soil samples at 320 m grid were collected from Chotanahalli micro-watershed and assessed for pH, EC, soil organic carbon (SOC), DTPA-extractable micronutrients (Zn, Cu, Mn, Fe) and hot-water extractable B. The ranges of available Fe, Mn, Zn, Cu and B were 4.80–19.5, 9.34–20.2, 0.24–1.50, 0.36–1.02 and 0.25–0.83 mg kg^-1 with the corresponding mean values of 11.2, 15.9, 0.79, 0.7 and 0.49 mg kg^-1, respectively. Spatial interpolation revealed that the whole area under micro-watershed was sufficient in terms of Fe, Mn and Cu. However, 14.5 and 48.1% of the study area were deficient in Zn and B, respectively. Soil pH was negatively correlated with available Fe and Mn content. Whereas, SOC showed positive correlation with available B content. Management practices that enhance B, Zn and SOC status of soils should be employed in the Chotanahalli micro-watershed region for sustainable crop production.