Estimation of vineyard pesticides mobility through soil column experiments and lysimeters study

Extensive use of pesticides in a conventional agriculture although necessary to improve crop production, may at the same time pose a threat to soil and water quality. Two main active substances were in focus of this research: glyphosate (broad-spectrum, post emergence, non-selective herbicide) and cypermethrin (synthetic pyrethroid insecticide), both commonly used in vineyards. Two locations were selected for the field trial: Baštica located on the flat coastal terrain, and Jazbina located on a hillslope terrain characteristic for vineyard production in the continental part of Croatia. At both field sites, zero tension lysimeters were installed and water balance components monitored throughout the year. Undisturbed soil columns were taken from both sites and used to estimate mobility of pesticides by applying irrigation and a known dosage of both pesticides (optimum field quantity) in a controlled environment. Water samples from lysimeters and leachate from soil columns were taken periodically and analyzed for active substances. In addition, soil samples were taken, and initial pesticides concentrations were measured, as well as the soil sorption capacity at each site. First results indicate that the sorption coefficient (Kd) was the main process limiting pesticide mobility in soil. Both pesticides have high capacity to be adsorbed by the soil particles and organic matter present in the soil surface layer. Thus, the possible losses of pesticides through surface runoff (e.g. colloidal transport) or by soil water preferential flow pathways will be further studied.