Herbicide losses in runoff events from a field with a low slope: role of a vegetative filter strip.
Herbicide runoff and the effects of a narrow vegetative filter strip (VFS) were studied on an arable field in the low-lying plains of the Veneto Region (north-east Italy). Cultivated plots were compared with and without a 6m wide VFS composed of trees, shrubs and grass. Natural and simulated runoff were monitored during 2000 and 2001. Herbicides applied on the field were: metolachlor (2184-2254 g ha(-1)), terbuthylazine (1000-1127 g ha(-1)) and isoproturon (1000 g ha(-1)). The VFS reduced both runoff depth (10.2-91.2%) and herbicide losses (85.7-97.9%) in the monitored rainfall events. Total herbicide loss with runoff was low (0.69-3.98 g ha(-1) without VFS, less than 0.27 g ha(-1) with VFS), but concentrations were sometimes very high, especially of terbuthylazine and isoproturon during the first events after treatment. In these events there was a high probability of exceeding the ecotoxicological endpoint for algae, but the VFS helped to reduce the potential risk. Two VFS effectiveness mechanisms were identified: (i) dilution, and (ii) a "sponge-like" effect, which temporarily trapped chemicals inside the VFS before releasing them.
Vianello
Monica
M
Dipartimento di Agronomia Ambientale e Produzioni Vegetali, Università di Padova, Agripolis, Viale dell'Universitá 16, 35020 Legnaro (PD), Italy. monica.vianello@unipd.it
Vischetti
Costantino
C
Scarponi
Luciano
L
Zanin
Giuseppe
G
D000081:Acetamides / Q000032:analysis; D000818:Animals; D004784:Environmental Monitoring; D056890:Eukaryota; D031751:Festuca; D005399:Fishes; D006540:Herbicides / Q000032:analysis*; D010671:Phenylurea Compounds / Q000032:analysis; D011891:Rain; D018570:Risk Assessment; D012989:Soil Pollutants / Q000032:analysis; D014227:Triazines / Q000032:analysis; D027925:Viburnum; D014872:Water Movements; D014874:Water Pollutants, Chemical / Q000032:analysis; D014876:Water Pollution / Q000517:prevention & control*
D000081:Acetamides; D006540:Herbicides; D010671:Phenylurea Compounds; D012989:Soil Pollutants; D014227:Triazines; D014874:Water Pollutants, Chemical; C028904:isoproturon; C037565:terbutylazine; C051786:metolachlor