Temporal variability and drain spacing effect of sub surface drainage system on drain water properties in adsali sugarcane grown in sodic vertisol

Abstract

A field experiment was conducted during 2024-25 at the Agricultural Research Station, Kasbe Digraj, Sangli (Maharashtra, India) to assess the temporal variability and effect of different drain spacings of a subsurface drainage system (SSDS) on drain water properties in adsali sugarcane grown on sodic vertisols. The SSDS was installed at 1.2 m depth with lateral spacings of 15, 25, and 40 m, along with a control (no drainage). Standard reclamation practices including gypsum application (5 t ha⁻¹) and dhaincha green manuring were followed. Drain water samples were periodically collected after rainfall and irrigation events and analyzed for pH, electrical conductivity (EC), Ca²⁺, Mg²⁺, Na⁺, HCO₃⁻, Cl⁻, and sodium adsorption ratio (SAR). Results indicated that total annual water use was 314.92 lakh L ha⁻¹, of which 63.38% was drained through the SSDS. The 40 m drain spacing recorded significantly lower mean values of pH (7.26), EC (2.87 dS m⁻¹), and SAR (2.95) compared to the control (7.51, 6.92 dS m⁻¹, and 3.69, respectively). Ion concentrations of HCO₃⁻, Ca²⁺, Mg²⁺, Na⁺, and Cl⁻ also decreased with increasing drain spacing, though differences among 15, 25, and 40 m were statistically non-significant. Temporal variation in drain water quality was observed across months, influenced by fertilizer applications and seasonal rainfall. Overall, the 40 m drain spacing was found most effective in reducing salt and ion losses, improving drain water quality, and minimizing environmental impacts under sodic vertisol conditions cultivated with adsali sugarcane.