Abstract: The introduction of extensive irrigation systems, particularly the Indira Gandhi Canal Project, has significantly transformed the agricultural landscape of Ganganagar District in northwestern Rajasthan. While irrigation has substantially improved agricultural productivity in this semi-arid region, it has also induced notable changes in the chemical composition of soils, raising concerns about long-term soil health and sustainability. This research investigates the geographical variations in soil chemical properties influenced by different irrigation regimes—namely canal irrigation, tubewell irrigation, and rainfed conditions—across selected regions of Ganganagar District. Soil samples were collected from representative sites in both command (canal-irrigated) and uncommand (non-canal) areas, and analyzed for critical chemical parameters including soil pH, electrical conductivity (EC), organic carbon (OC), available nitrogen (N), phosphorus (P), potassium (K), and selected micronutrients like zinc (Zn), iron (Fe), and manganese (Mn). The study reveals that canal-irrigated areas, especially those under long-term and intensive irrigation, tend to exhibit elevated pH and EC levels, indicating increased alkalinity and salinization due to the upward movement and accumulation of salts. These conditions are further exacerbated in areas where poor-quality groundwater is used, particularly in tail-end regions with limited canal supply. Additionally, a declining trend in organic carbon and essential macronutrients was observed, possibly due to intensive cropping, reduced organic matter input, and nutrient leaching. In contrast, rainfed areas showed relatively stable chemical properties, albeit with lower fertility indices. The spatial analysis underscores the uneven impact of irrigation on soil quality, influenced by factors such as irrigation water source, soil texture, cropping intensity, and drainage conditions. From a geographical perspective, the study highlights the need for location-specific soil and water management strategies to prevent further degradation. Measures such as conjunctive use of surface and groundwater, adoption of soil ameliorants (e.g., gypsum), crop rotation, and organic manure application are suggested to maintain soil chemical balance. The research calls for integrated approaches in agricultural planning that align with both environmental sustainability and regional development objectives.
