S-Carvone Formulation Based on Granules of Organoclay to Modulate Its Losses and Phytotoxicity in Soil

Abstract

Based on the effects that allelochemicals can exert over organisms, their use as alternatives to synthetic pesticides has been proposed. To this aim, it is important to understand their behavior in soils as allelochemicals can readily dissipate by different routes. In this work, novel granules based on the commercial organoclay Cloisite® 10A were prepared as a new strategy for the possible application of S-carvone as a bioherbicide, overcoming its rapid dissipation in the environment. Batch release, degradation, mobility, and phytotoxicity tests in soil were performed. Until now, the phytotoxicity of organoclay-based formulations of S-carvone in soil has not been studied. The release of S-carvone in water from the granules occurred slowly. There were no differences in the persistence of the allelochemical after its application to soil as a free compound (readily available form) or supported on granules. However, the granulated formulation reduced and delayed the leaching of S-carvone, thus controlling its downward movement in soil columns, as compared to the free S-carvone. Bioassays revealed that S-carvone supported on granules reduced the germination and aerial biomass of Lactuca sativa L. to a greater extent than the free compound. Our results demonstrated that the prepared formulation of S-carvone, based on granules of the commercial organoclay Cloisite® 10A, could be used to control transport losses, such as leaching or volatilization, increasing the bioefficacy of the allelochemical. These findings could inspire further investigations for the preparation of novel formulations of monoterpenes as potential bioherbicides.