Reclamation of a Saline Sodic Soil Using Synthetic Polymers and Gypsum
- M. F. Zahow and
- C. Amrhein
The water infiltration rate of saline sodic soils often limits the rate of reclamation. Column leaching studies were conducted to determine if water-soluble, synthetic polymers would be beneficial in improving the hydraulic conductivity and aid reclamation of a heavy-textured, salt-affected soil. Soil samples from a swelling soil (fine, montmorillonitic [calcareous] Thermic Vertic Haplaquoll) were collected from a field site that had exchangeable sodium percentages (ESP) of 8, 12, 20, 25, 32, and 35. The air-dried soil samples were treated with polyacrylamide polymers (one nonionic and two anionic) and one cationic guar-derivative polymer at a rate of 50 mg kg−1. Polymer treatments had a highly significant effect on increasing the saturated hydraulic conductivity of the soil samples with ESP values <15, but had no significant effect on the samples with values > 15. The addition of gypsum increased the hydraulic conductivity from 0.0 to 0.063 mm h−1 in the soil with an ESP of 32. When polymers were used in conjunction with gypsum, the hydraulic conductivity increased to 0.28 mm h−1. We attributed the improvement in hydraulic conductivity with polymer treatment at low ESP values and in the gypsum-treated soil to a reduction in soil slaking and dispersion. At ESP values > 15, an additional mechanism that may have been controlling the hydraulic conductivity was swelling, and none of the polymers reduced soil swelling.
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