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Résumé :
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Data were collected from four small watersheds (1.3 to 2.7 ha) located in the southern Piedmont region. Two watersheds were managed without conservation measures; the other two watersheds were parallel-terraced and included grassed waterways for soil erosion control. Total losses of applied herbicides were affected by the occurence of runoff in close proximity to application date, mode of application, and persistence in the soil runoff zone. Most of the total annual losses by runoff were in the first three runoff events for all compounds except paraquat. Runoff of trifluralin was very low (0.1 to 0.3 % of the annual application). Total runoff losses of other herbicides were commonly less than 1.0 % except when runoff occured shortly after application. Sediment yield from terraced watersheds was significantly less than from watersheds managed without terraces. Except for paraquat, however, pesticide yields in runoff were not reduced in propotion to sediment reduction because solution trnsport was the major mode of loss for the soluble herbicide phase. Annual runoff losses of soluble plant nutrients were 5.0 and 1.3 kg/ha for chloride and nitrate, restectively. Losses of soluble phosphorus from both watersheds were very low, about 380 g/ha.
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