Effect of sodium adsorption ratio and electric conductivity of the applied water on infiltration in a sandy-loam soil

Abstract

Infiltration measurements using a double-ring infiltrometer were conducted on a sandy-loam soil located in Saudi Arabia. The measurements were performed for an undisturbed soil. The effect of sodium adsorption ratio (SAR) and electric conductivity (EC) of the applied water on infiltration rate was examined. The infiltration rate at the initial time was high, in the order 305 > 240 > 137 > 104 > 65 mm/h for SAR of 3.34, 3.52, 4.14, 4.18, and 7.60, respectively. The results showed that 180 min after the initial time of measurement in the sandy-loam soil, the final infiltration rates were in the range of 21.1–44.0 mm/h for the different qualities of water considered in this study, with an average value of 33.8 mm/h. Hence, the infiltration rate is sensitive to the SAR of the applied water. The final infiltration rate (IR_f) and the final cumulative infiltration depth (Z_f) after 180 min could be predicted using the following equations:

IR_f (mm/h) = 49.399 + 6.691 × EC (dS/m) – 6.740 × SAR (—) R2 = 0.939
Z_f (mm) = 148.198 + 20.074 × EC (dS/m) – 20.221 × SAR (—) R2 = 0.9387

Keywords: Infiltration, Kostiakov, electric conductivity, sodium adsorption ratio