Sulphuric acid for reducing sodium hazard of irrigation water

Abstract

The effect of sulfuric acid applied to irrigation water on sodium adsorption ratio, exchangeable sodium percentage, and saturated hydraulic conductivity was studied by one greenhouse and two laboratory experiments using five soil samples and five different waters mixed to simulate those used for irrigation in the Southwestern United States. Application of sulfuric acid to the irrigation water decreased the sodium adsorption ratio and the exchangeable sodium percentage. Conventional equations based on the pile parameter over-estimate the effect of bicarbonates on the sodium adsorption ratio, while the equation based on carbonate equilibrium gave a more realistic estimate. The measured exchangeable sodium percentage was found to be proportional to the calculated sodium adsorption ratio. The proportionality constant for the five soils studied was 0.76 divided by the square root of the leaching fraction. Acid application also increased the rate of water movement when sodium adsorption ratio was greater than 7.0 in some soils without lowering the pH to acidic ranges.