Characteristics of dust particles abraded from treated seed

Dieter Foqué, W Devarrewaere, P Verboven, David Nuyttens

    Onderzoeksoutput: Hoofdstuk in Boek/Rapport/CongresprocedureC3: Congres abstract


    Differing amounts of abraded dressing particles can be produced during sowing as a result of the dressing process, storage conditions, handling, and transport before the drilling and breaking of seeds inside the drill. One of the most important factors affecting the risk of dust drift is the seed treatment quality (Nuyttens et al, 2013). The Heubach method - widely accepted to assess the abrasion potential of seed treatment coatings - has a limited size range compared to the total potentially driftable fraction and no quantitative relation between Heubach values and field drift values has been established. More information about the chemical and physical characteristics of abraded particles of pesticide-coated seeds is needed to better understand the complex phenomenon of dust drift and for the development of predictive dust drift models (Devarrewaere et al. 2013, Foqué et al 2013). In this study, a detailed dust characterization is performed in terms of amount of fine dust, total dust load, particle size distribution, particle shape, particle density and concentration of active ingredient (a.i.).
    The abrasion potential of 5 sugar beet, 16 cereal (oat, barley, wheat, spelt) and 16 maize batches (provided by seed companies, farmers and contractors) was assessed using the Heubach method to evaluate the effect of crop, species, seed treatment and handling. Heubach values were expressed in g dust /100 kg of seeds, g dust/ 100 000 kernels and in g dust/ha. For maize, average values were 0.83 g/100 kg, 0.31 g/100 000 kernels and 0.19 g/ha, while for sugar beet much lower values were found of 0.52 g/100 kg, 0.01g/100 000 kernels and 0.01 g/ha. For different types of cereals, values ranged from 1.55-4.07 g/100 kg, 0.09-0.28 g/100 000 kernels and 2.56-9.15 g/ha. So, based on the Heubach tests cereals seem to have the highest potential risk of dust drift because of their high sowing density in combination with a high dust load.
    One representative maize batch and one wheat batch were selected for a detailed physical and chemical analysis. The total dust load, determined by dry sieving (2 mm and 5 mm aperture size), was 65.5 g/100 kg or 23.1 g/100 000 kernels for maize and 7.01 g/100 kg or 0.38 g/100 000 kernels for wheat. The particle size distribution of these dust samples was measured by sonic sieving (12 sieves with aperture sizes from 10 to 1000 µm ) as well as by laser diffraction (Malvern Mastersizer S). A good correlation was found between both techniques. Wheat dust had a finer particle size distribution (D10 = 16.4 µm, D50 = 163.5 µm, D90 = 787.8 µm) compared with maize dust (D10 = 87.3 µm, D50 = 243.0 µm, D90 = 946.7 µm). For the 13 size fractions, a.i. concentration generally decreased with increasing particle size. The density of both dust samples was measured by pycnometry. Finally, 3D images of dust were obtained with X-ray microtomography (Skyscan 1172, Bruker Micro-CT) and allowed to separate individual particles with an equivalent diameter larger than 10 µm up to more than 1 mm and measure their shape characteristics. The particle sphericity depended on size and was significantly smaller than 1 for the larger particle fraction.
    TitelDust emissions from seed drills
    UitgeverijAssociation of Applied Biologists
    StatusGepubliceerd - 2013
    EvenementDust Emissions from Seed Drills - Berlin-Dahlem, Duitsland
    Duur: 14-mrt-201315-mrt-2013


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