Soil salts reduce hydration of polymeric: Gels and affect moisture characteristics of soil

Hydration of a hydrophilic crosslinked polystyrene (gel) in deionized water at 65 g of gel per g of soil was studied. Four different soil types were selected, three were light-textured soils (loamy sand and sandy clay loam) and the other a clay. Container capacity, field capacity, permanent wilting point, and available water for these soils were measured for gel contents equal to 0, 0.1, 0.2, and 0.3%. Absorption capacity of the gels when incorporated into the soil decreased considerably compared to its absorption in pure water. This was attributed to the increased ionic strength of soil moisture and the formation of additional ionic crosslinks in the gel network due to the presence of multivalent ions in the soils. It was found also that container capacity, field capacity, and available water capacity increased with the gel content in soil, whereas the permanent wilting point was not significantly affected.