Potential of some soil amendments in reducing leaching of fipronil to groundwater

The efficacy of different soil amendments in reducing the leaching of fipronil to groundwater was examined in soil columns under laboratory conditions. The polyvinyl chloride columns were sequentially filled with soils of different depths simulating natural conditions. Different soil amendments namely fresh cow dung (FCD) slurry @ 0.5 t ha^-1, farmyard manure @ 5.0 t ha^-1, press mud compost @ 5.0 t ha^-1, cereal straw @ 5.0 t ha^-1 and gypsum @ 5.0 t ha^-1 were applied on the top soil. The application of farmyard manure, cereal straw and gypsum decreased the soil pH, and except FCD, all the amendments increased the electrical conductivity of the soil. Among different soil amendments, press mud compost and cereal straw were the most effective in reducing leaching of the fipronil to groundwater. Fipronil residues in soil columns after leaching indicated that all soil amendments effectively increased the retention of fipronil in soil; however, press mud compost and cereal straw also dissipated higher amount of fipronil. The results also revealed a higher retention of applied fipronil with lower degradation and leaching under application of 0.5 t FCD ha^-1 as organic amendment in soil in comparison with the unamended soil.

Keywords
Cereal straw; Efficacy; Polyvinyl chloride (PVC) columns; Press mud compost