Clay-Organic Complexes and Interactions

Development of a new long-term drought resilient soil water retention technology

“…Spatially distributed clay layers with low permeability within some highly permeable soils increase the retention of both soil water and nutrients (Hillel 2004). Clay mixed into surface horizons of sand soils (Al-Omran et al 1991;Ismail and Ozowa 2007) and incorporations of thin layers of clay water barriers located 15 to 30 cm (6 to 12 in) beneath sand soil surfaces (Saunders 1941;Mortland et al 1957;Chen and Qian 1984) provide modest improvements in soil water retention crop yield. However, applications of clay and silt materials in sandy soils are costly and create heterogeneous soils (Ismail and Ozowa 2007).…”

Interaction of Diclofop and Diclofop-Methyl with Al3+-, Fe3+-, and Cu2+-Saturated Montmorillonite

“…Insofar as the adsorption of organic molecules is concerned, clay minerals are among the most active soil components (Mortland, 1970(Mortland, , 1975Crosby, 1976). The adsorption of pesticides onto clay minerals is generally disfavored because of the competition with water.…”

Effects of Increasing Potassium Chloride and Calcium Chloride Ionic Strength on Pesticide Sorption by Potassium‐ and Calcium‐Smectite

“…This view is exemplified by the reliance on soil organic carbon-normalized sorption coefficients (K OC ) to predict the fate and transport of organic compounds in soils. However, several recent studies and a few earlier ones provide clear evidence that soil minerals can function as effective adsorbents for pesticides and organic contaminants under environmentally relevant conditions (Bailey et al, 1968;Bowman, 1973;Boyd et al, 2001;Celis et al, 1998;Haderlein et al, 1996;Hundal et al, 2001;Johnston et al, 2002;Laird et al, 1992;Mortland, 1970;Sheng et al, 2002;Zhu et al, 2004). For important categories of pesticides (e.g., triazines, carbamates, ureas, nitrophenols, benzonitrile) and organic contaminants (e.g., nitroaromatics), sorption by clays can be equal or greater than that by SOM based on comparisons of sorption by a unit mass of isolated clay minerals vs. SOM and by synthetic clay-organic matter complexes (Li et al, 2003;Sheng et al, 2001).…”