Overwaaien, atmosferische depositie en afspoelen van bestrijdingsmiddelen in de akkerbouw en groenteteelt op kleigrond

De omvang van enkele bovengrondse emissieroutes voor bestrijdingsmiddelen naar waterlopen bij lage vollegrondsteelten is onderzocht. Het overwaaien van spuitvloeistof bij de toediening leidt veelal tot grote overschrijding van de ecotoxicologische norm en van de norm voor oppervlaktewater bestemd voor de drinkwaterbereiding. De 90e-percentielwaarden voor bestrijdingsmiddelen in de neerslag liggen veelal wat boven de drinkwaternorm van 0,1 Šg/l. Het onderzoek naar de afspoeling over het bodemoppervlakdient te worden voortgezet voor gevoelige situaties (bodem, neerslag), omdat de betrokken bestrijdingsmiddelconcentraties hoog kunnen zijn

Emissies van bestrijdingsmiddelen en nutriënten in de bloembollenteelt; adsorptie en omzetting van bestrijdingsmiddelen in bloembollengronden

Voor uitspoelingsberekeningen zijn in het laboratorium de adsorptie en omzetting bestudeerd van drie bestrijdingsmiddelen in twee zandige bloembollengronden. Metamitron werd in bouwvoormateriaal matig geadsorbeerd en had korte halfwaardetijden (drie dagen) door microbiële adaptatie. In met water verzadigd ondergrondmateriaal was de halfwaardetijd van metamitron veertig dagen. Het omzettingsprodukt HTI van chloorthalonil werd sterk geadsorbeerd en de omzetting verliep zeer traag. Het omzettingsprodukt3-chloorallylalcohol van 1,3-dichloorpropeen werd nauwelijks geadsorbeerd in ondergrondmateriaal en de halveringstijd was enkele dagen. De gemeten adsorptie en omzettingssnelheid wijken af van de verwachtingen gebaseerd op literatuurgegevens

Measures to reduce glyphosate runoff from hard surfaces, 2: effect of time interval between application and first precipitation event

In this research the effect of moisture conditions of hard surfaces on emission of herbicides from hard surfaces was quantified. In addition the dissipation of glyphosate applied on brick-pavement is determined in time. The outdoor experiment was carried out on 3 and 17 June 2003. In previous research (part 1) the effect of a buffer zone around drains of sewage systems on glyphosate runoff was tested experimentally (Luijendijk et al., 2003

Transport of water, bromide ion, nutrients and the pesticides bentazone and imidacloprid in a cracking, tile drained clay soil at Andelst, the Netherlands

The aim of this study was to perform a field experiment to collect a high quality data set suitable for validating and improving pesticide leaching models and nutrient leaching models for drained and cracking clay soils. The transport of water, bromide, nutrients and the pesticides bentazone and imidacloprid was studied on a 1.2 ha experimental plot. Moisture profiles and groundwater tables were measured, starting in November 1997. Winter wheat was sown on 23 October 1997 and harvested on 20 August 1998. Bentazone and bromide were applied at 7 April 1998; imidacloprid was applied at 27 May when the soil was almost completely covered by the crop. The amount present in soil was measured within 2 days after application (32 sampling cores) and was found to vary between 80% of the nominal dose (imidacloprid) to 110 % (for bentazone). Manuring and soil cultivations were as usual for the wheat crop. Soil profiles were sampled at eight times (16 cores at each date, last in April 1999). Drain flow was continuously recorded and the water flow proportionally sampled for analysis of the test compounds. Groundwater was sampled periodically from sets of permanently placed filters at four depths at 16 sites. Sorption isotherms of the pesticides were measured with soil from 0-25 cm. Transformation rates of the pesticides were measured at different temperatures in soil material from topsoil and subsoil layers. Soil hydraulic properties and shrinkage characteristics were measured in the laboratory. Meteorological data (i.e. rainfall, air temperature, global radiation, air humidity etc.) groundwater levels and soil temperatures at three depths were monitored continuously. After 56 days, about 80% of the bromide dose was taken up by the crop, which demonstrates that bromide is not a suitable tracer in cropped soil during the growing season. After that time the bromide was gradually released again into the soil. Preferential transport through cracks and macropores of all test compounds was measured both in summer and in winter. This resulted in the highest concentration of bromide and bentazone measured in drain water already 21 days after application following 56 mm rainfall. Imidacloprid was already detected in groundwater at 1.3-1.5 m depth, 11 days after application, following 65 mm rainfall. High peaks in nitrate concentrations in the groundwater at 1.00-1.50 m depth and in the drain water were detected within 14-18 days after the first fertilizer application, following 94 mm of rainfall. Extreme high peaks in concentrations of ortho-P and soluble organic-P were measured in the drain water at respectively 2 days and 37 after slurry application (the only phosphorus application during the experiment). For nitrate concentrations in the drain water there were indications for bypass by preferential flow of `clean` rainwater to the drains

Movement of water, bromide ion and the pesticides ethoprophos and bentazone measured in a sandy soil in Vredepeel (The Netherlands)

The aim of this study was to collect a data set suitable for testing pesticide leaching models in the case of a Dutch sandy soil with a shallow groundwater table. The movement of water, bromide ion and the behaviour of the pesticides ethoprophos and bentazone was studied. The substances were applied after sowing winter wheat in autumn 1990. This late application time is unusual for bentazone: it was selected on scientific grounds (without agricultural purpose). Rainfall, groundwater level and soil temperature were monitored continuously at the experimental field (80 m long and 54 m wide) until spring 1992. Soil profiles were sampled at 1, 22, 42, 103, 214, 278 and 474 d after application (16 profiles at each date). In the laboratory, pesticide transformation rates were measured with soil material from 0-25, 50-100 and 100-200 cm depth. Sorption isotherms were measured with material from 0-25 cm depth. Concentration profiles showed that mobility increased in the sequence ethoprophos - bentazone - bromide ion. Ethoprophos movement was limited to the top 25 cm layer whereas bentazone leached to below 1 m depth. At the end of the study, the concentrations of ethoprophos and bentazone were below the detection limit (0.2-2 g dm-3) in all soil layers between 25 and 120 cm depth

Movement of water, bromide and the pesticides ethoprophos and bentazone in a sandy soil: the Vredepeel data set

The aim of this study was to collect a data set suitable for testing pesticide leaching models in the case of a Dutch sandy soil with a shallow groundwater table. The movement of water, bromide ion and the behaviour of the pesticides ethoprophos and bentazone was studied. The substances were applied after sowing winter wheat in autumn 1990. This late application time is unusual for bentazone: it was selected on scientific grounds (without agricultural purpose). Rainfall, groundwater level and soil temperature were monitored continuously at the experimental field (80 m long and 54 m wide) until spring 1992. Soil profiles were sampled at 1, 103, 278 and 474 days after application (16 profiles at each date). In the laboratory, pesticide transformation rates were measured with soil material from 0–25, 50–100 and 100–200 cm depth. Sorption isotherms were measured with material from 0–25 cm depth. Concentration profiles showed that mobility increased in the sequence ethoprophos — bentazone — bromide ion. Ethoprophos movement was limited to the top 25 cm layer whereas bentazone leached to below 1 m depth. At the end of the study, the concentrations of ethoprophos and bentazone were below the detection limit (0.2–2 μg dm−3) in all soil layers between 25 and 120 cm depth. Recommended values for the most important input parameters of pesticide leaching models are presented