GIS Techniques for Soil Fertility Assessment and Soil Health Improvement in Watershed Area of Northern Karnataka

The ever-growing global population and increasing demands for food security have led to intensified agricultural practices, which in turn have altered soil biotic and abiotic factors, significantly impacting soil health and ecosystems. Soil health is a critical component for achieving sustainable agriculture. Current land and crop management practices have resulted in issues such as yield stagnation, nutrient depletion, soil degradation and decline in soil quality. To ensure food security and long-term sustainability, it is essential to conserve and manage land and soil resources while maintaining soil fertility. In this context, a sub-watershed in Jalawadha, covering an area of 780.86 ha in Devara Hipparagi taluk, Vijayapura district, Karnataka, was selected for soil nutrient assessment. Using GIS techniques, 13 mapping units were delineated based on soil-site characteristics. The study revealed that soil pH ranged from moderately to strongly alkaline. Organic carbon (OC) levels were low in 79.33 percent of the watershed area, and medium in 19.47 percent. Regarding major nutrients, most of the area had low levels of available Nitrogen (N) and Sulphur (S), medium levels of available Phosphorus (P), and high levels of Potassium (K). The GIS-based LRI of Jalawadha sub-watershed revealed alkaline soils with deficiencies of organic carbon, nitrogen, and sulphur, but adequate phosphorus and high potassium. These imbalances stress the need for integrated fertility management through balanced fertilizers with organic mulching, manures, crop residue incorporation, and amendments, which are vital to restore soil health, enhance productivity, and ensure sustainable agriculture.