Pesticide Chlorpyrifos Loss in Runoff From Andic Soil Potato Fields in Colombia: Comparison of Field Results With Gleams Predictions

Abstract

Runoff potential of chlorpyrifos was evaluated in a small scale study under simulated rainfall on a andic soil potato fields. Rainfall events were simulated (80 mm/h × 30 min) a 40 cm × 32 cm field plots with 8, 17, 30 and 40 % slope, 24 h after pesticide application. Sediment amounts and pesticide concentrations in sediment and water were determined in the runoff samples, pesticides residues attached to sediment were extracted by ultrasonification of 40 °C and centrifugation with hexane by GC-ECD with percentages of 94-98 % and residues in aqueous sample was quantified using a solid-phase extraction (SPE) and rotaevaporation in atmosphere of N₂ and GC-ECD, percentages of recuperation were determined between 89-98 %. The observed data in field used to fit sensitivity in the water balance calculus in model GLEAMS. Being observed that the pesticide component of the GLEAMS considers loss by runoff of chlorpyrifos in soil (sediment) and water with modeling efficiency (EF) 0.7 and 0.2, respectively. These data predicted the destiny and behaviour of pesticide in the field in andic soil of high mountain.