Bm. Berger, Factors influencing transformation rates and formation of products of phenylurea herbicides in soil, J AGR FOOD, 47(8), 1999, pp. 3389-3396
Transformation rates of phenylurea herbicides and their products were measu
red in native soil, sterile soil, soil suspensions, and soil inoculated wit
h pure cultures of microorganisms. In native soil, transformation rates gen
erally increased with decreasing adsorption of the herbicides, but correlat
ions with adsorption coefficients were poor. In sterile soil, substitution
patterns of the compounds influenced transformation rates. In soil suspensi
ons, transformation rates increased with lipophilicity of the herbicides. I
n sterilized soil inoculated with specific microorganisms, transformation w
as mainly influenced by substrate specificities of the microorganisms to re
active sites of the phenylureas. In all cases, N-demethylation was an impor
tant, but not the only, transformation pathway. The data indicate that tran
sformation rates of phenylureas in soils are affected by several parameters
, related to the soil, the compounds, and the type of transformation. Altho
ugh the results were gained in the laboratory under artificial conditions,
they form a basis to establish quantitative structure-reactivity relationsh
ips and provide explanations for quality and quantity of the formed product
s.