ADSORPTION, DEGRADATION AND LEACHING OF PIRIMICARB IN ORCHARD SOILS

This paper shows the results of experiments (adsorption, degradation and mobility) carried out to investigate the risk of pirimicarb leaching to groundwater, after its application to integrated fruit growing systems. Soil batches were collected from experimental fruit farms in Numansdorp and Zeewolde (The Netherlands). The distribution coefficients and the degradation rate coefficients for Numansdorp and Zeewolde soils, respectively, show a higher adsorption and degradation rate in the Zeewolde soil than in the Numansdorp soil. By leaching of pirimicarb in two soil columns, it was found that pirimicarb mobility is lower in the Zeewolde soil columns than in the Numansdorp ones but, in both cases, it is much lower than it would be expected from their adsorption coefficients. Pirimicarb is detected in the first effluents, however, the highest concentration remained in the upper 10 cm of the soil columns. A computation model simulating uniform water flow and instantaneous adsorption desorption equilibrium is not suitable to describe the leaching of pirimicarb in structured loamy soils at relatively high water flow-rates.