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

Abstract

Controlled release (CR) formulations can significantly influence the fate of carbofuran in the environment. The influence of three alginate-encapsulated CR formulations compared with the granular formulation (G10%) on the mobility of carbofuran in sandy clay loam soil and sandy loam soil was investigated. In flooded soil the leaching potential of the three alginate controlled release formulations tested was decreased more than nine times (not more than 3%) compared with the G10% (28%). Most of the released carbofuran was 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 data obtained for a sandy loam soil irrigated by drip irrigation showed that the greatest proportion of carbofuran leached through the columns was from the G10% (52%) compared with 3–4% from CR formulations over a 30-day period. The carbofuran concentrations found in different soil depths showed similar trends to those for the flooded soil. Based on the residue levels recorded within the 20 cm depth, the relative retention ratio of carbofuran in sandy clay loam versus sandy loam soil was 1·2[ratio ]1 for the controlled release formulations and 1·9[ratio ]1 for the G10%.