Geospatial Assessment and Mapping of Soil Fertility Status in the Ballakere Micro-watershed of Vitalapura Sub-watershed

Abstract

This study aims to assess the fertility status of the Ballakere micro-watershed, located in the Lower Tungabhadra catchment—a region of vital importance for agricultural output and environmental conservation. Soil samples were systematically collected from a depth of 0–20 cm and analyzed using standardized procedures to determine key soil properties. Advanced geospatial tools, including ArcGIS and kriging interpolation techniques, were employed to develop detailed maps illustrating the spatial distribution of soil nutrients and overall fertility. The results revealed soil pH values ranging from neutral to slightly alkaline (6.70 to 7.58), with all soils being non-saline, reflecting the area's diverse soil characteristics. However, the organic carbon content was found to be low (0.30 to 0.49 g kg⁻¹), which may negatively affect soil health and agricultural productivity. Available nitrogen levels varied widely, from low to high (194.72 to 243.20 kg ha⁻¹), indicating potential limitations for crop performance. Phosphorus (24.28 to 58.04 kg ha⁻¹), potassium (168.80 to 395.19 kg ha⁻¹), and sulphur (14.72 to 19.98 mg kg⁻¹) levels were also found to vary, all of which are critical for effective nutrient uptake and plant growth. Exchangeable calcium and magnesium levels were found to be adequate. Among micronutrients, boron was consistently low (0.38 to 0.44 mg kg⁻¹), while iron, copper, and manganese levels were generally sufficient. Zinc availability ranged from deficient to sufficient across the area. These findings highlight the importance of evaluating soil nutrient status to support data-driven land management practices, enhance sustainable agriculture, improve crop yields, and maintain ecological balance within micro-watershed ecosystems.