Affiliations: College of Resources and Environmental Sciences, China
Agriculture University, Beijing 100094, China | Institute of Agriculture Environmental Protection,
Hunan Agriculture University, Changsha 410128, China | Institute of Geographical Sciences and Natural
Resources Research, Chinese Academy of Sciences, Beijing 100101, China
Abstract: Laboratory experiments about the dissipation, adsorption and
translocation in four paddy topsoils were conducted in this paper. From the
results it can be concluded as follows: the dissipation rate of clomazone
differed greatly in different paddy soil derived from different parent
materials. The half-lives for clomazone degradation in paddy soils ranged from
5.7 to 22.0 d. The order of clomazone dissipation rate was reddish yellow paddy
soil > alluvial sandy paddy soil > yellow clayey paddy soil > purple
sandy paddy soil. Clomazone sorption quantity was significantly correlated with
organic carbon (R^2 = 0.62) and clay content
(R^2 = 0.67) in the tested paddy soils.Positive correlation
was found between apparent K_d value and cation exchange
content (CEC). The consequences for the adsorption of different soils were
purple sandy paddy soil > yellow clayey paddy soil > reddish yellow paddy
soil > alluvial sandy paddy soil. Under the simulated rainfall of 200 mm
through four different unsaturated soil lysimeters over 24 h, clomazone was
readily to be leached into lower surface soil and there was about 2.6%–4.2%of
applied clomazone leached out of 20 cm cultivated soil layer. Translocation
experiments showed that the order of clomazone leaching ability was: alluvial
sandy paddy soil > reddish yellow paddy soil > yellow clayey paddy soil
> purple sandy paddy soil. Simple regression results manifested that factors
like CEC, organic carbon, clay, and adsorption rate constant had been
negatively correlated with the percentage of clomazone loss from soil
lysimeters.
