Atrazine losses from corn fields in the Little Vermilion River watershed in east central Illinois

High levels of atrazine in the Little Vermilion River (LVR) and Georgetown Lake, which supplies drinking water for 5,000 residents, have been detected Each late spring or summer; the level of atrazine has exceeded the USEPA M aximum Contaminant Level (MCL). In this study atrazine losses from surface runoff and tile flow under different cropping and soil management practices for four years of monitoring were studied. The loss from surface flow was much less than that from tile flow. The major loss of atrazine occurred wit hin three months after application and was generally caused by heavy rainfa ll, Early application without anything growing in the field or atr azine ap plication some rime Inter than planting caused an increase of atrazine loss es during rainfall. This suggests that the greatest use of atrazine was at the beginning of weed growth. Therefore, rite best time for atrazine applic ation is just before or at the beginning of weed growth. The amount, timing , and distribution of rainfall and stage of plant growth influence the move ment of atrazine.