Premium
Release of Herbicides from Clay Minerals as a Function of Water Content: I. Kaolinite
Author(s) -
Don Scott H.,
Lutz J. F.
Publication year - 1971
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1971.03615995003500030017x
Subject(s) - simazine , kaolinite , chemistry , atrazine , adsorption , environmental chemistry , pesticide , agronomy , mineralogy , biology , organic chemistry
The influence of water content on the release of six herbicides from kaolinite was studied. Kaolinite suspensions were treated with 14 C‐labeled herbicides at rates of 1 and 4 µg/g (based on dry weight of clay). Extracts of the soil solution were obtained at successively increased increments of pressure from 0.3 to 15 bars, using the pressure membrane extractor. The following determinations were made: (i) volume of extract for each pressure‐increment; (ii) concentration of herbicide in the extract, as measured by liquid scintillation; (iii) amount of herbicide remaining, as calculated by difference; and (iv) pH of the extract. The results show that for all herbicides used, except simazine, the concentration in the extracts decreased with increasing pressure increments. The decreases were greatest with diuron and chlorpropham. Simazine concentration was from two to three times greater in the high than in the low‐pressure extracts. High concentrations in low‐pressure extracts suggest that plant availability is high and that movement with water could be a problem with high rainfall under field conditions. Fluometuron and 2,4‐D were negatively adsorbed; the others were positively adsorbed. The order of release in terms of total recovery of herbicide applied at the 1‐ppm rate was: fluometuron > 2,4‐D > atrazine > chlorpropham > simazine > diuron. The order was the same for the 4‐ppm rate except that 2,4‐D was greater than fluometuron. The total recovery of the herbicides in the extracts ranged from 12.0% for diuron to 92.1 for fluometuron.