Organo-clay formulations of pesticides: Reduced leaching and photodegradation

Yasser El-Nahhal, Tomas Undabeytia, Tamara Polubesova, Yael Golda Mishael, Shlomo Nir*, Baruch Rubin

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

69 Scopus citations


Adsorption of organic cations on several clay minerals is reviewed with an emphasis on the effect of ionic strength and modeling. The clay exchanged with suitable organic cations forms a basis for ecologically acceptable formulations of herbicides with reduced leaching, ground water contamination and enhanced weed control efficacy. Incomplete neutralization of the clay surface charge by an organic cation may be advantageous in achieving maximal adsorption of hydrophobic herbicides. One conclusion from these studies is that optimization of clay-based herbicide formulations requires a selection of structurally compatible organic cations preadsorbed on the clay at optimal coverage. New experimental results are presented for alachlor formulations, which significantly reduce herbicide leaching under conditions of heavy irrigation. We were able to demonstrate that organo-clay formulations of alachlor and metolachlor can increase crop yields in a 1-year field experiment. The photostabilization of pesticides is reviewed and improved organo-clay formulations of the herbicides trifluralin and norflurazon are described. A pillared clay, nanocomposite micro- and/or meso porous material, was effective in reducing leaching and in conferring photostabilization, without added organic cations.

Original languageAmerican English
Pages (from-to)309-326
Number of pages18
JournalApplied Clay Science
Issue number5-6
StatePublished - May 2001

Bibliographical note

Funding Information:
This research was partly supported by Grant G-0405-95 from the German–Israeli Foundation (G.I.F) for Scientific Research and Development, and partly by Grant 1317 from the Israeli Ministry of Science, Culture and Sports. Dr. Undabeytia is grateful to the Spanish Government for a research contract (Project N.AMB98-0888).


  • Alachlor
  • Herbicide leaching
  • Metolachlor
  • Norflurazon
  • Organic cations
  • Organo-clay formulation
  • Photostabilization
  • Trifluralin


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