Influence of Soil Moisture on Thiobencarb Concentration in Soil Solution

Abstract

The relationship between soil moisture and concentration of soil-applied thiobencarb [S-(4-chlorobenzyl) diethyl thiocarbamate] in soil solution was investigated. When thiobencarb was applied to soil (low-humic andosols) at the same dosages based on air-dried weight, its concentration in soil solution was similar at any soil moisture level tested (45-75%, moisture weight percentage). Thus, the total amount of thiobencarb in soil solution increased as soil moisture increased regardless of the dosage applied. It was found that the partition coefficient of thiobencarb was inversely proportional to the application dosage at a given soil moisture condition in the soil. Bioassay with soil solution which was extracted by centrifugation with a double tube under various soil moisture conditions (45-75%) showed little difference in shoot growth of Echinochloa crus-galli (L.) Beauv. var. praticola Ohwi and Digitaria ciliaris Koeler. The rate of growth inhibition was almost identical with that of the freshly prepared thiobencarb solution. This supports that the concentration in soil solution is closely related to the herbicidal activity of soil-applied thiobencarb, although most of the thiobencarb was contained in the soil phase. Therefore, it was concluded that thiobencarb concentration in soil solution was almost constant under different soil moisture conditions.

Phytotoxic activity of pethoxamid in soil under different moisture conditions

“…The inhibition was increased as the soil moisture increased in any designated concentration, although 80% moisture content was higher than the field capacity. The results suggest that the phytotoxic activity of pethoxamid in the soil is significantly influenced by the soil moisture, as reported for thiobencarb (Lee et al . 1996).…”

“…The soil moisture content at herbicide application is one of the important factors affecting the phytotoxic activities and the behaviors of soil‐applied herbicides (Moyer 1987; Nash 1988; Lee et al . 1996; Roy et al .…”

“…2003). However, there is only limited information on the relationship between the phytotoxic activity and the behavior of herbicides in soil (Lee et al . 1996, 2004).…”

Bioavailability of the Nano-Unit <SUP>14</SUP>C-Agrochemicals Under Various Water Potential

“…[1][2][3][4][5] Previous studies have determined bioavailability by equating water potential to centrifugal gravity. [6][7][8][9][10][11] Additionally, several studies have reported * Author to whom correspondence should be addressed. that bioactivity of herbicides in soil solution was the most important parameter for determination of their phytotoxicity.…”

“…that bioactivity of herbicides in soil solution was the most important parameter for determination of their phytotoxicity. [6][7][8][9][10] However, the total bioavailable amount in soil solution may vary due to varying water volumes, which might enhance potential bioavailability and phytotoxicity as water potential increases. 7 10 Use of a tank-mixture of herbicides rather than one herbicide is a common practice that enables reduction of the number of applications made in the field.…”