Availability of a cationic herbicide adsorbed on clay minerals to cucumber seedlings.

Montmorillonitic and kaolinitic clays are effective in decreasing the toxicity of paraquat, an organic cation, to cucumber plants. The cation was adsorbed on the surface of the kaolinite clay particles and slowly became available to the plants. When it was adsorbed in the interlayer spacings of the montmorillonite clay, however, it was not available to the plants.