Adsporption , Desorption and Mobility of s- Triazine Herbicides in Soils

Abstract

Adsorption, desorption and movement of atrazine, ametryn, dimethametryn and simazine associated with their respective14 C-herbicides were studied for fice commonly occuring soils of central Thailand; Bangkhen clay, Pakchong clay loam, Kampang Saen silty loam, Sattahip loamy sand and Nampong sand. Organic carbon contents of the soils by weight varied from 0.3 to 2.9% clay fractions ranged from 1 to 57%. The greatest amount of hervicides were adsorbed onto Bangkhen clay, followed by Pakchong clay loam, Kampang Saen silty loam, Nampong sane, and Sattahip loamy sand respectively, Adsorption of s - triazines onto soil were governed by amount and type of clays and organic matter. The average K value across soil types showed that dimethametryn by amount and type of clays and organic matter. The average K value across soil types showed that dimethametryn was adsorbed in greatest amount, followed by simazine, ametryn and atrazine. All herbicides were desorbed in all soils. Atrazine and simazine were desorbed from Bangkhen clay and Nampong sand more repidly than from other soils. Ametryn and dimethametryn were desorbed more from Banghken clay than other soils. The greatest movement of hervicides occurred in Sattahip loamy sand followed by Nampong sane, Pakchong clay loam, Kampang Saen silty loan, and Bangkhen clay respectively. The most mobile herbicide was atrazine followed by simazine, ametryn, and dimethametryn.