Relationships between the Degradation Rate of the Herbicide Pyrazoxyfen and Soil Properties

Abstract

Relationships between the degradation rate of the herbicide pyrazoxyfen (2-[4-(2, 4dichlorobenzoyl)-1, 3-dimethylpyrazol-5-yloxy]-acetophenone) and soil properties were investigated. In the experiment, pyrazol-3-14C-labeled and unlabeled pyrazoxyfens were incubated in five paddy soils under flooded and upland conditions. The degradation rate of pyrazoxyfen differed greatly according to the properties and conditions of soils. Pyrazoxyfen tended to degrade rapidly in mineral soils and slowly in humic volcanic ash soils with its halflife being 3-5 and 5-34 days, respectively. In the same soil, the degradation was faster under flooded conditions (half-life of less than 10 days) than under upland moisture conditions (half-life of 4-34 days). Under all the experimental conditions the degradation rate was negatively correlated with the cation-exchange capacity and the organic-matter content of a soil. The correlation was also negative with the CAN ratio and the maximum water holding capacity, but the correlation coefficient differed according to experimental conditions.

Persistence and leaching of β‐cyfluthrin in alluvial soil of India

“…Smith et al 8 reported that cyfluthrin dissipated readily under anaerobic soil conditions. Faster dissipation under submerged/flooded condition has also been reported for pendimethalin,9 chlorothalonil19 and pyrazoxyfen 20…”