Effect of maturing turfgrass soils on the leaching of the herbicide mecoprop

Leaching of the herbicide mecoprop, [2-(4-chloro-2-methyl-phenoxy)propionic acid] (MCPP), was studied on three types of turfgrass soils; silt loam, fine sandy loam and acid sand, to assess the potential for ground water contamination. Each soil was prepared in plots as free draining lysimeters and seeded with Penncross creeping grass to simulate golf course fairways. The downward migration of MCPP was determined from collected leachate water and residue analysis were done by high performance liquid chromatography. The extent of pesticide leaching was determined to be a function of interval after herbicide application, amount of irrigation water and maturity of the turfgrass stand. The irrigation and water collection patterns do not explain most of the differences in the leaching profiles, in particular of the sand plots. The concentration of mecoprop in the sand leachates was high compared to the finer textured soils but decreased substantially with increasing time after herbicide application in all three soils as well as with maturity of the grass and with more biomass from first to third year application. Where groundwater monitoring is being done, MCPP is a likely candidate for residue analysis if the site has very sandy soils.