Pesticide fate in sodded kentucky bluegrass lawns in response to irrigation

Abstract

Fertilizers and pesticides applied to home lawns can contaminate surface and groundwater making them unfit for aquatic organisms and human consumption. Application of fertilizers and pesticides can improve the aesthetics of a home lawn, improve turfgrass shoot and root density, water use, organic matter accumulation, and other factors known to be influential in urban hydrology. A field study determined the impact of applying home landscape pesticides with or without supplemental irrigation of leaching into groundwater or runoff to surface water. Free-draining lysimeters having a sandy loam soil (coarse-loamy, mixed, active, mesic Lamellic Hapludalf) were used to monitor total volume and nutrients and pesticides losses. Samples from natural precipitation events were analysed for pendimethalin [N-(1-ethylpropyl)-3,4-dimethyl-2, 6-dinitrobenzenamine] applied in spring, mecoprop [2-(4-Chloro-2-methylphenoxy) propionic acid]+2, 4-D (2,4-dichlorophenoxyacetic acid) applied both in late spring and early fall, and bifenthrin [(2-methyl-1,1-biphenyl-3-y1)-methyl-3-(2-chloro-3,3,3-trifluoro-1-propenyl)-2,2-dimethyl cyclopropanecarboxylate] applied in late summer. Pesticide concentrations fluctuated over time, but no differences in concentrations were observed from irrigated or non-irrigated turfgrass for any pesticide. Mecoprop and 2,4-D were the most mobile and values found in runoff during establishment were above maximum contaminant levels (MCL) for U.S. standards. Surface runoff of lawn pesticides were observed at concentrations several magnitudes higher than leachate. The total extent of pesticide runoff was 0.71%, 1.3%, 6.0%, and 0.003% of the amount applied for 2,4-D, mecoprop, pendimethalin and bifenthrin, respectively. With the exception of one sampling period, pendimethalin concentrations in runoff and leachate were low; however, when applied during a period of minimal turf growth and high precipitation, pendimethalin could contribute significantly to surface water pollution.