Quantifying and Mapping of Major, Secondary and Micronutrient Status of Tomato Growing Soils in Kolar District, Karnataka Using GIS and GPS Approach

Assessment of land use-induced changes in soil properties is essential for addressing issues of spatial variability in soil fertility and sustainable land productivity. In view of this, a study was conducted to assess the impact of spatial variability on physicochemical properties, macro and micro nutrient status of 75 farmers fields of tomato growing areas of Kolar district, Karnataka. Arc Map with spatial analyst function of Arc GIS software was used to prepare soil fertility maps, which would act as an important tool for soil as well as nutrient management for sustainable crop production by using Global Positioning System coordinates. The results revealed that the soils under investigation were acidic to alkaline in reaction (pH 4.41 to 8.13), mostly non saline and low to high in organic carbon status (0.53 to 1.95%). Available nitrogen, phosphorus, potassium and sulphur content varied from 150.53-348.10, 6.4 - 111.44, 147.18 - 916.61 and 12.29 - 103.8 kg ha-1. Exchangeable Ca, Mg are in the range of 2.5 – 14.2 and 1.2 – 6.6 C mol (p+) kg. The GIS-aided thematic maps with respect to available zinc, 6.67 (low), 21.33 (medium) and 72 (high) per cent samples were categorized, based on the existing critical limits. All the studied samples i.e., 100 per cent were high in copper content, 65.33, 30.67 and 4 per cent samples of Mn, 25.33, 32 and 42.67 per cent samples of Fe, were categorized as low, medium and high in nutrient status respectively. With respect to available boron 16.67 per cent was under low, 38.09 per cent was under medium and 45.24 per cent was under high nutrient status. The nutrient index (NI) of tomato growing areas of Kolar district revealed that N (1.19), manganese (1.39) and iron (1.29) were categorized as low, available boron (2.17) as medium and P (2.65), K (2.71), S (2.65) zinc (2.75), copper (3.0) as high nutrient index category.