Laboratory Degradation Studies of Bentazone, Dichlorprop, MCPA, and Propiconazole in Norwegian Soils

Abstract

Laboratory degradation studies were performed in Norwegian soils using two commercial formulations (Tilt and Triagran-P) containing either propiconazole alone or a combination of bentazone, dichlorprop, and MCPA. These soils included a fine sandy loam from Hole and a loam from Kroer, both of which are representative of Norwegian agricultural soils. The third soil was a highly decomposed organic material from the Froland forest. A fourth soil from the Skuterud watershed was used only for propiconazole degradation. After 84 d, less than 0.1% of the initial MCPA concentration remained in all three selected soils. For dichlorprop, the same results were found for the fine sandy loam and the organic-rich soil, but in the loam, 26% of the initial concentration remained. After 84 d, less than 0.1% of the initial concentration of bentazone remained in the organic-rich soil, but in the loam and the fine sandy loam 52 and 69% remained, respectively. Propiconazole was shown to be different from the other pesticides by its persistence. Amounts of initial concentration remaining varied from 40, 70, and 82% in the reference soils after 84 d for the organic-rich soil, fine sandy loam, and loam, respectively. The organic-rich soil showed the highest capacity to decompose all four pesticides. The results from the agricultural soils and the Skuterud watershed showed that the persistence of propiconazole was high. Pesticide degradation was approximated to first-order kinetics. Slow rates of degradation, where more than 50% of the pesticide remained in the soil after the 84-d duration of the experiment, did not fit well with first-order kinetics.

Environmental Fate of the Herbicide MCPA in Two Soils as Affected by the Presence of Wheat Ash

“…However, it has been observed that MCPA can be utilized by soil bacteria as a carbon source and converted to 4-chloro-2-methylphenol in the first step (Bollag et al 1967;Crespín et al 2001). The half-lives of MCPA for these two soils are similar to those reported in other studies (Torstensson et al 1975;Thorstensen and Lode 2001).…”

The earthworm Aporrectodea caliginosa stimulates abundance and activity of phenoxyalkanoic acid herbicide degraders

“…Such results were consistently obtained in three independent sets of soil column experiments with initial MCPA concentrations ranging from 15 to 50 mg g À1 dw (Figures 2 and 3a). Given extraction efficiencies of MCPA from soil 495% (see Materials and methods), the polarity of MCPA and the stability of MCPA in sterile soil (Thorstensen and Lode, 2001), disappearance of MCPA in soil is regarded as degradation further on. MCPA was not detected after 37 days of incubation ( Figure 3a) and in control soil without MCPA (data not shown).…”

Effect of Biocompost-Amendment on Degradation of Triazoles Fungicides in Soil

“…However, Bromilow et al (1999) and Kim et al (2003) showed that mineralization of propiconazole was faster in sandy loam soil than the clay loam suggesting that due to lesser sorption of the fungicide in sandy loam soil than clay loam, the fungicide was more accessible to biological degradation. Thorestensen and Lode (2001) have reported that propiconazole degraded faster in soil with lower organic carbon content and its half life values in sandy loam (OC -1.4%) and loam (OC -2.5%) soils were 137 and 210 days, respectively.…”