Chemosphere 2009-07-01

Evolution of soil biological properties after addition of glyphosate, diflufenican and glyphosate+diflufenican herbicides.

Manuel Tejada

Index: Chemosphere 76(3) , 365-73, (2009)

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Abstract

The aim of this paper was to study in laboratory the degradation and the effects on biological properties in two soils after the addition of glyphosate, diflufenican and glyphosate+diflufenican. One hundred grams of sieved soil (<2mm) were mixed with (i) 13mL of Zarpa (16% glyphosate and 4% diflufenican) prepared in a water solution of 1L (0.52g of glyphosate and 2.08g of diflufenican), (ii) 5.2mL of Round up (40% glyphosate), prepared in a water solution of 1L (0.52g of glyphosate), and (iii) 1.19mL of Brodal (43.5% diflufenican), prepared in a water solution of 1L (2.08g of diflufenican). Soil samples were collected after 0, 1, 5, 10, 15, 30, 60, 120 and 180d of incubation and analyzed for microbial biomass-C and dehydrogenase, urease, beta-glucosidase, phosphatase, arylsulphatase activities and glyphosate and diflufenican contents. At the end of the experiment, in the clayey texture soil the glyphosate and diflufenican contents were higher 50% and 30.7%, respectively, for the glyphosate+diflufenican treatment compared to glyphosate and diflufenican treatments, respectively. In the sandy loam texture soil the glyphosate and diflufenican contents were higher (38.9% and 39.4%, respectively) when the glyphosate and diflufenican were added as Zarpa than Round up or Brodal. The application of glyphosate+diflufenican mixture to soil increased the toxic effects of both herbicides in the soil biological activity and the individual soil persistence of each herbicide.