ATRAZINE FATE ON A TILE DRAINED FIELD IN NORTHERN NEW-YORK - A CASE-STUDY

Only by understanding the transport and degradation mechanisms of atra zine on farms can measures be taken to minimize atrazine concentration s that reach natural environments. The fate of atrazine on a tile drai ned farm in northern New York during the spring was followed. The larg est stream was sampled as well as individual tile lines from one field after snowmelt began in March 1994, until the flow ceased in early Ju ne 1994. Prior to the first application of atrazine on the farm in 199 4, atrazine concentrations in the stream ranged between 0 and 0.4 mu g L(-1). Immediately following an 0.8 inch rainfall event, 6 days after the application of 1.4 kg of atrazine on 1 ha of a tile drained field , atrazine concentrations at a tile line outlet feeding into the strea m reached 34.5 mu g L(-1). After mixing with other inflows, the atrazi ne concentration in the stream was 6.4 mu g L(-1). The atrazine concen tration decreased along the 1450 foot stream. Analysis of eight tile l ines which drained a research field showed a direct correlation betwee n increased flow rates with increased atrazine concentration, No-tilla ge practices may lead to slightly higher concentrations of atrazine in the tile lines.