Assessment of Irrigation Water Quality in the Experimental Farm of Tiruvannamalai District, Tamil Nadu, India

Assessment of irrigation water quality is essential for sustainable agricultural production, particularly in regions where water resources are limited. The present study was carried out to evaluate the irrigation water quality of the experimental farm of the Agricultural College and Research Institute, Vazhavachanur, Tiruvannamalai district, Tamil Nadu. Water samples were collected from different blocks and analysed for physico-chemical parameters such as pH, electrical conductivity (EC), major cations (Ca, Mg, Na, K) and anions (HCO₃⁻, Cl⁻, SO₄²⁻), total dissolved solids (TDS), and total suspended solids (TSS).To assess irrigation water quality, various indices were computed, including Soluble Sodium Percentage (SSP), Potential Salinity (PS), Sodium Adsorption Ratio (SAR), Kelley’s Ratio (KR), Residual Sodium Carbonate (RSC), Permeability Index (PI), and Magnesium Ratio (MR), based on established methods. The results indicated that the pH ranged from 7.01 to 7.75, reflecting a neutral to mildly alkaline nature, while EC ranged from 1.40 to 1.60 dS m⁻¹, classifying the water as moderately saline. Computed irrigation water quality indices such as soluble sodium percentage (SSP), sodium adsorption ratio (SAR), sodium ratio, residual sodium carbonate (RSC), permeability index (PI) and magnesium ratio (MR) were also evaluated. The SSP (17.46–32.55%) and SAR (0.99–2.10) values indicated low sodium hazard, while negative RSC values (-16.36 to -7.20 mg L⁻¹) suggested the dominance of calcium and magnesium over carbonate and bicarbonate ions. The sodium ratio values were less than unity, indicating no risk of sodium accumulation. Based on EC, SAR and RSC classification, all water samples were categorised under good quality for irrigation. However, potential salinity values indicated moderate salinity risk, necessitating proper management practices. The irrigation water in the study area is suitable for agricultural use with appropriate soil and water management strategies such as leaching, adequate drainage and cultivation of salt-tolerant crops to ensure long-term soil health and productivity.