LABORATORY APPARATUS FOR STUDYING PESTICIDE LEACHING IN INTACT SOIL CORES

This paper describes the design, construction, operation, and performance of an apparatus useful for studying pesticide leaching through intact soil cores. A technique is described for rapidly mounting intact soil cores. A turntable is used to support and rotate 12 or more soil cores under an oscillating dripper unit capable of simulating rainfall intensities of 1 to 30mm/h. Each soil core is attached to a filtration flask which is connected to a -10 to -20 Kpa vacuum supply. The CV of the rainfall delivery rate over a range of 2-12 mm/h averaged 3.7%. Dye studies using intact soil cores indicated that water movement at the soil-wall interface was not faster than through the soil matrix. An experiment conducted to evaluate atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] leaching through soil cores obtained from no-till(NT) and conventional-till(CT) fields indicated consistently greater leaching through CT cores. The capability of precise application of simulated rain, accommodation of large number of soil cores, and ease of modification to meet a wide range of research parameters make this apparatus useful for the laboratory evaluation of soil-water-pesticide interactions.