Enhanced degradation of metalaxyl in agricultural soils of Sao Paulo State, Brazil

This work investigated the effect of repeated applications on enhanced degr adation of metalaxyl in two different agricultural soils used for cultivati on of orange and lemon from Casa Branca and Itapetininga districts of Sao P aulo State, Brazil. Soil samples were collected from areas repeatedly treat ed with commercial ridomil 50GR for six successive years, and from other ar eas never exposed to this fungicide. At the laboratory soil samples receive d a C-14-metalaxyl solution and its degradation was studied through radiome tric techniques to measure biomineralization and recovery of extractable- a nd soil-bound products. Enhanced degradation was verified only in one soil, although partial degradation and mineralization of the fungicide were dete cted in both soils. The different rates and patterns of metalaxyl degradati on in the soils were probably due to their different physical, chemical, an d biological characteristics.