The acetochlor PGW program required a total of eight trials to be conducted across a range of soil textures and geographical locations. The geographic locations covered are representative of areas of acetochlor use. The data generated during this program will be used to calibrate mathematical models to allow further estimates of any leaching potential to be conducted. The test plots at each trial site are essentially square, approximately 3.2 acres in size and are adjacent to a smaller control plot of approximately 0.4 acres. Each trial site also contains a large number of ground water monitoring wells which are screened at varying depths within the aquifer.
Ground water is sampled from the wells using dedicated pumps.
Both suction lysimeters and ground water monitoring wells are sampled frequently and the suction lysimeters provide an early warning system for the potential movement of the test chemical to ground water. Acetochlor was applied to the test plot as a single spray application to pre or post-emergent corn. Weather stations are installed at each trial site and record environmental and climatic data. After application the movement of acetochlor is studied by the collection of soil, soil pore water and ground water samples. The sampling phase of the study is two years minimum but for the six trials conducted during 1995 and 1996, has continued for at least 4 years.