The influence of irrigation with Lake Kinneret water on the chemistry of soils in the headwater basin

Abstract

The farming areas in the catchment of Lake Kinneret basin are irrigated with Dan Spring waters, characterized by a concentration of 10 mg/L of Cl. Climate change simulation predicts that by the year 2050, the flow of the headwater springs will drop by 20%, a finding that poses a significant threat to the future of farming in the basin. The Israel Water Authority proposed irrigating Kinneret water after dilution with the Dan Spring water. To test the possible ramifications on soil health, three irrigation treatments were used, including Kinneret water (300 mg/L Cl⁻), mix-diluted water (150 mg/L Cl⁻), and control irrigation with Dan water (10 mg/L Cl⁻). The experiment was conducted in a factorial structure (5 common soils × 3 treatments × 6 repetitions) in 25-L pots. A total of 945 weekly leachates were sampled, and Cl, pH, electrical conductivity (EC), and sodium adsorption ratio (SAR) were determined. To determine the exchangeable sodium percentage (ESP), soil samples were collected from two depths (0–10 cm and 30–40 cm). Significant differences were found between the three treatments in all salinity and sodicity parameters (p < 0.001) measured in leachates and soils. The difference between the treatments was most pronounced in the summer when the Kinneret-irrigated soils exhibited means of EC, 3584 µS/cm; Cl, 1694 mg/L; SAR, 10.07 meq/L^0.5; and ESP, 8.2%. Changes in salinity and sodicity in leachates and soils corresponded well to changes in evaporation. This test study strongly suggests that changing water sources for irrigation because of climate change may increase soil salinity across the entire Mediterranean region.