Effects of Irrigation with Agricultural Drainage Water on Soil Physical and Chemical Properties in a Semi-Arid Region

ROMANIAN AGRICULTURAL RESEARCH, cilt.43, ss.563-573, 2026 (Scopus)

Water scarcity in semi-arid regions has increased interest in reusing agricultural drainage water for

irrigation; however, its impacts on soil systems require quantitative evaluation under field-representative

conditions. This study investigated the effects of two years of irrigation with agricultural drainage water on soil

physical and chemical properties under semi-arid conditions in southeastern Türkiye within the Southeastern

Anatolia Project (GAP) irrigation network. A lysimeter-based experiment under field-representative

environmental conditions was conducted using agricultural soils collected from cultivated lands and exposed to

natural climatic variability. Four irrigation treatments were applied: freshwater (control), untreated

agricultural drainage water, treated drainage water, and mixed drainage water. Soil samples were collected at

depths of 0-30 and 30-60 cm after the second irrigation season. Soil physical properties (texture, bulk density,

and water retention characteristics) and chemical properties (pH, electrical conductivity, exchangeable cations,

cation exchange capacity, and exchangeable sodium percentage) were analyzed using standard methods. Soil

physical properties showed only minor treatment- and depth-related variations, with no substantial

deterioration in bulk density or available water content. In contrast, soil chemical parameters responded more

sensitively to irrigation water quality. Electrical conductivity increased from initial values of 810-1000 µS cm⁻¹

to 820-1860 µS cm⁻¹ after two years, with the highest value observed in the 0-30 cm layer under untreated

drainage water. Across treatments, EC values were generally higher in the 0-30 cm layer, indicating

preferential accumulation of surface salts under semi-arid conditions. Exchangeable sodium percentage

increased in drainage water-irrigated soils, particularly under untreated drainage water, indicating the onset of

sodicity-related processes. Although measured values remained below critical thresholds during the study

period, depth-dependent increases in salinity and sodium-related parameters represent early indicators of

potential soil degradation. The results suggest that short-term reuse of agricultural drainage water may be

feasible, provided that continuous monitoring of soil salinity and sodicity is implemented to ensure long-term

soil quality in semi-arid environments.