Adsorption and leaching behaviour of bispyribac-sodium in soils.
Adsorption-desorption of the herbicide bispyribac-sodium was studied in four Indian soil types. Bispyribac-sodium was poorly adsorbed in the four soils and adsorption decreased with an increase in the herbicide concentration in solution. Freundlich adsorption coefficient (Kf) values for bispyribac-sodium ranged between 0.37 and 0.87. Slope (1/n) values varied from 0.2 to 0.31 suggesting that bispyribac-sodium adsorption was highly dependent on its initial concentration in solution. Bispyribac-sodium adsorption showed a positive correlation with soil pH (r = 0.809) and clay content (r = 0.699) while no correlation was observed with the organic carbon (r = 0.063) content. Sorbed herbicide was completely desorbed during a single desorption step suggesting that the herbicide was bound by weak adsorptive forces. Leaching studies of herbicide in soil 1 packed column indicated complete loss of soil applied herbicide under a simulated rainfall equivalent to 162 mm.
Division of Agricultural Chemicals, Indian Agricultural Research Institute, New Delhi, 110 012, India, drneerasingh@yahoo.com.
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D000327:Adsorption; D000538:Aluminum Silicates; D001565:Benzoates / Q000737:chemistry*; D002244:Carbon / Q000737:chemistry; D000077215:Clay; D006540:Herbicides / Q000032:analysis / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007194:India; D008956:Models, Chemical; D011743:Pyrimidines / Q000737:chemistry*; D012964:Sodium / Q000737:chemistry; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis* / Q000737:chemistry; D012995:Solubility
D000538:Aluminum Silicates; D001565:Benzoates; D006540:Herbicides; D011743:Pyrimidines; D012987:Soil; D012989:Soil Pollutants; D002244:Carbon; D012964:Sodium; C549011:bispyribac; D000077215:Clay