Leaching and mobility of carbofuran from granular and alginate controlled release formulations

Controlled release (CR) formulations can significantly influence the fate o f carbofuran in the environment. The influence of three alginate-encapsulat ed CR formulations compared with the granular formulation (G10%) on the mob ility of carbofuran in sandy clay loam soil and sandy loam soil was investi gated. In flooded soil the leaching potential of the three alginate control led release formulations tested was decreased more than nine times (not mor e than 3%) compared with the G10% (28%). Most of the released carbofuran wa s confined to the top 0-5 cm of the soil column followed by the second 5-10 cm layer and the least was found in the fourth section (15-20 cm). The dat a obtained for a sandy loam soil irrigated by drip irrigation showed that t he greatest proportion of carbofuran leached through the columns was from t he G10% (52%) compared with 3-4% from CR formulations over a 30-day period. The carbofuran concentrations found in different soil depths showed simila r trends to those for the flooded soil. Based on the residue levels recorde d within the 20 cm depth, the relative retention ratio of carbofuran in san dy clay loam versus sandy loam soil was 1.2:1 for the controlled release fo rmulations and 1.9:1 for the G10%.