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Effect of Irrigation Water pH on Saturated Hydraulic Conductivity and Electrokinetic Properties of Acidic, Neutral, and Alkaline Soils
Author(s) -
Ali Aram,
Biggs Andrew J.W.,
Marchuk Alla,
Bennett John McL.
Publication year - 2019
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2019.04.0123
Subject(s) - alkalinity , soil water , cation exchange capacity , chemistry , leaching (pedology) , hydraulic conductivity , soil ph , sodium adsorption ratio , alkali soil , environmental chemistry , irrigation , soil science , environmental science , agronomy , organic chemistry , drip irrigation , biology
The demand for the use of marginal‐quality water as an irrigation resource is increasing in arid and semiarid region lands due to the freshwater shortage. Marginal waters usually have high salinity and high alkalinity and may contain high proportions of ions such as sodium. This study investigated the impact of irrigation water pH on saturated hydraulic conductivity ( K s ), cation exchange capacity, net particle charge, and dispersivity of soils. Nine soils with differing pH, alkalinity, clay content, and mineralogy were used in leaching column experiments, with solutions of varying sodium adsorption ratio (20 and 40), electrical conductivity (0.8, 1.5, 2.5, 5, 10, 25, and 50 dS m −1 ), and pH (6, 7, 8, and 9). The desired pH was achieved by adjusting the HCO 3 − /Cl − ratio and CO 2 partial pressure using CO 2 gas with 99.9% purity. Results showed that the increase of solution pH causes an increase in net negative charges on clay particles, resulting in higher exchangeable cations, negative ζ‐potential, and clay dispersion and movement of dislodged particles into pore spaces, resulting in K s reduction. This effect was more evident for acidic and low‐clay‐content soils. The K s reduction in relation to pH was less for smectitic and high clay content soil than for kaolinite dominant soils for all concentrations, suggesting resiliency of the smectitic soils under irrigation water with high pH. Results reinforce that it is essential to consider the original pH, clay content, and mineral of the soil and the pH, electrical conductivity, and sodium adsorption ratio of the irrigation water to accurately predict the K s reduction of the soil.