Determination the effect of pendimethalin on weeds and microbial population in different soil structure

This study was carried out to investigate the effects of pendimethalin on some weeds and microorganisms in soils have different textures. Pendimethalin (a.i.: 450 g/l) were applied pre-emergence at the rate of 75, 150 and 300 ml/da (recommended dose) doses in the pots including soils with different properties and some weed seeds. In efficiency, although some differences determined depending on the soil type, in general a relationship associated with organic matter content not fully determined. Considering the doses; as doses increased, effectiveness increased as well as low doses had also effect on some weeds. In order to determine the effect of pendimethalin on microbiological and biochemical properties of tin textured soil, 300 ml/da was applied. Although the herbicide effected adversely to N mineralization at first 40 days, the effect disappeared after 60 day and any adverse effects have been found in terms of some parameters as CO2 generation, Dehydrogenase and Alkaline Phosphatase enzyme activity, the enzyme alkaline phosphatase activity, the number of general bacteria, fungus and Azotobacter number. Eventually, 300 ml/da dose of this herbicide could be used safely in terms of these parameters. In order to accurate recommendation, detail studies will be conducted on field condition are needed. Key Words: Soil Structure, Pendimethalin, Weed, Microbial Activity