Freezing and Thawing, and Wetting and Drying in Soils Treated with Organic Chemicals

Abstract Laboratory experiments were performed to determine the effects of cycles of freezing and thawing or of wetting and drying on the percentage of water stable aggregates of soils treated with organic chemicals. The chemicals used were HPAN (a hydrolyzed polyacrylonitrile), SC‐50 (a water soluble sodium methyl siliconate) and PR‐51 (a water soluble alkylated aromatic sulfonate). Rates of application were 0.1% HPAN, 0.2% SC‐50 or 0.0013% PR‐51. Seven different soils were tested. Two of the soils were separately treated with HPAN, SC‐50 and PR‐51, and five additional soils were treated only with HPAN. The soils were tested for water stability, by wet sieving, after 0, 1, 5, 10 and 20 cycles of freezing and thawing, and after 0, 1, 5 and 10 cycles of wetting and drying. Results showed that soils which had undergone the effects of freezing and thawing generally had a lower percentage of aggregates > 0.25 mm., than those which had not been subjected to the process; this was also true for cycles of wetting and drying but to a lesser extent. The different soils responded with significant difference to the effects of freezing and thawing and of wetting and drying in interaction with the organic chemicals, except that the use of PR‐51 resulted in no significant differences.