| Abstract
| - A field study was undertaken to investigate runoff and leaching loss of the herbicide pendimethalinin turfgrass land of loamy sand soil. A series of plots constructed in a golf course fairway weresurface-applied with pendimethalin SC formulation at the rate of 2.25 or 4.50 kg a.i./ha and subjectedto simulated rainfall at 2.0 cm/day for 10 consecutive days. Runoff losses of pendimethalin werethe highest at the first rainfall and then gradually decreased with time. The first runoff eventcontained pendimethalin in its highest concentration, and in subsequent runoff samples theconcentration decreased exponentially. The ranges of pendimethalin concentration were 80.9−18.2and 177.4−48.6 μg/L in the standard and double doses, respectively. Total losses by 20 cm of rainfallfor 10 days reached 0.81 and 1.22% of the initial deposits at 2.25 and 4.50 kg a.i./ha, respectively.Pendimethalin concentration in the leachate collected at 30-cm soil depth was quite lower thanthat in the runoff, and the concentration rapidly decreased from 4.3−4.7 to 0.2−0.4 μg/L during the10 days of rainfall treatment. Soil residue analysis at 45 and 90 days after pendimethalin treatmentshowed that more than 90% of the residue remained at the top 10 cm of soil depth. Low runoff andleaching confirmed that lateral and downward movement of the herbicide should be limited in turfsoil. The half-life of pendimethalin under field conditions was 23−30 days and was not affected byapplication dose and rainfall treatment, but longer persistence was observed under laboratoryconditions. Considering low runoff and leaching, as well as relatively short persistence in soil, it isconcluded that little environmental carryover of pendimethalin would be expected in turfgrass land. Keywords: Golf course; herbicides; leaching; pendimethalin; runoff; turfgrass
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