Sulfuric Acid Effect on Bicarbonate Concentration and Sodium Adsorption Ratio in Soils.

Water sources used to irrigate turfgrass areas in the arid southwestern states of the US can contain high levels of bicarbonates. As a result, unsightly lime deposits can stain leaves, soil pH can increase, and soil permeability can be reduced. To address the problem, turfgrass managers inject sulfuric acid into the irrigation water. However, it is unclear, whether or not such an injection is useful and necessary to improve soil conditions. Sulfuric acid injection is believed to be helpful when bicarbonates are high enough to have Ca⁺² and Mg⁺² precipitating in the form of carbonates from the soil solution and at the same time Na⁺ content is also high to present a possible concern. However, when Na⁺concentration is low, information is lacking whether or not bicarbonates alone pose a risk and if water acidification is necessary.

To investigate the effect of injecting sulfuric acid into irrigation water on chemical and physical properties of soil, a column experiment using water with a high level of bicarbonates (250 ppm) and Sodium Adsorption Ratio of either high (13) or low (2.4) have been conducted at New Mexico State University. Soil columns measuring 10 cm in diameter and 45 cm in depth filled with a loamy sand were irrigated with four different water qualities. To collect leachate, Soil Solution Access Tubes (SSAT) were inserted at soil depths of 10 and 20 cm, and free draining water was collected at the base of the columns. Samples were analyzed monthly for pH and EC, Ca, Mg, and Na, and bicarbonates. Irrigation water was applied twice a week based on reference evapotranspiration for short grass for a total 6 months. At the end of the research period they received an amount matches the annual ETos for the Las Cruces area.