Some physicochemical and environmental factors affecting transformation rates and sorption of the herbicide metamitron in soil
1996
Vink, J.P.M. | Zee, S.E.A.T. van der
In addition to the molecular structure of a pesticide, environmental conditions may influence its persistence through their effect on the growth and activity of pesticide-degrading micro-organisms. As a result, transformation rates may decrease rapidly when a compound is leached into subsoil. Metamitron sorption isotherms were determined and incubation series were set up for a sandy loam soil, simulating single and combination effects that occur during transport of metamitron into subsoils. K(OC) values increased with increasing depth from 185 to 700 litre kg-1. A combination of conditions that are unfavourable for microbial activity, such as low temperature (5 degrees C), low concentrations (0.5 mg kg-1) and a large sorbed fraction (K(OC) = 700) resulted in half-lives of over one year. Oxygen inhibition decreased the transformation rate of metamitron from 0.058 to 0.019 day-1. In order of significance, the transformation of metamitron appears to be a function of temperature, oxygen availability and sorption to organic carbon. Increasing doses did not change transformation rates significantly, although different transformation pathways were observed.
Show more [+] Less [-]AGROVOC Keywords
Bibliographic information
This bibliographic record has been provided by National Agricultural Library