Original papersWind tunnel and CFD study of dust dispersion from pesticide-treated maize seed
Introduction
Seeds of many crops are dressed with pesticides to protect the seedlings from pests and diseases. Maize seed is commonly treated with insecticides of the neonicotinoid family, including clothianidin, thiamethoxam and imidacloprid (Krupke and Long, 2015). These insecticides are highly toxic for honey bees (Apis mellifera) and other useful pollinators and can induce various sublethal effects (Godfray et al., 2015, Iwasa et al., 2004, Whitehorn et al., 2012, Stanley et al., 2015, Schneider et al., 2012). In recent years, multiple routes of exposure of neonicotinoids to pollinators have been identified (Krupke et al., 2012, Van Der Sluijs et al., 2015). Emission of abraded seed treatment dust during sowing is one of these routes (Nuyttens et al., 2013). In vacuum-based precision drilling of maize, a central fan generates a depression in the seeding elements of the seeder for seed singulation. If dust particles are abraded from the seed dressing due to friction, they are emitted along with the exhaust air from the fan into the environment. This has caused serious pollinator poisoning incidents in the past (Pistorius et al., 2009, Bortolotti et al., 2009, Cutler et al., 2014).
Since the correlation between pesticide dust drift and honey bee colony collapses was first observed, the phenomenon was studied in controlled conditions and in (semi-)field conditions. The number of true field experiments (Heimbach et al., 2014, Biocca et al., 2015, Girolami et al., 2012, Pochi et al., 2012, Tapparo et al., 2012), in which whole fields were sown with pesticide-treated seed by vacuum precision drills, has been very limited because field studies are expensive, complex, time-consuming and poorly reproducible due to variable wind conditions and dust properties. Furthermore, even when reproducible dust drift patterns are measured, the findings are likely limited to the specific setup and conditions of the study, as a result of the wide variety of soil and meteorological conditions, dust properties, seed drill designs, fan configurations and operational parameters such as the vacuum level.
Complementing experiments with simulations is a useful approach to deal with these limitations. Computational fluid dynamics (CFD) is a modeling technique that is increasingly used for the simulation of complex particle-laden flows (ERCOFTAC, 2008). It was successfully applied to the simulation of phenomena similar to dust drift, such as droplet drift during field crop spraying (Baetens et al., 2007) and orchard spraying (Endalew et al., 2010, Duga et al., 2014, Duga et al., 2015), allowing for a quantitative comparison of sprayer designs and wind conditions. Currently, no model of any kind is available for dust drift from sowing operations.
The aim of this study was to develop a 3D CFD model of the dispersion of seed treatment dust in an air flow, and validate this model with results of a wind tunnel experiment, in which three size fractions of seed abrasion dust were released at three air velocities and deposition was measured at six distances downwind. The physicochemical properties of the wind tunnel dust samples were characterized and implemented in the CFD model. Dust trajectories were predicted using Lagrangian particle tracking (LPT), in which the position of a number of representative particles is tracked over time by assessing the forces that act on the particles and calculating the resulting acceleration. In this case, only gravity and drag were considered. To calculate these forces and the deposition of active ingredient (a.i.) on the ground accurately, it is crucial that the irregular physicochemical properties (Devarrewaere et al., 2015, Foqué et al., 2014) of the seed treatment dust are accurately described. For gravity, these properties are particle size, the true density of the solid material, and the internal air porosity; for drag, this is particle shape. The results of the wind tunnel experiment and the CFD simulations will be discussed and, ultimately, the use of this model in the simulation of dust drift in field-realistic scenarios will be considered.
Section snippets
Sample preparation
Dust was obtained by aspiration of loose dust particles from maize seeds during the seed treatment process and packaging in a commercial seed treatment facility. The seed was treated with a product containing methiocarb. The dust was separated in seven size fractions (<80 μm, 80–160 μm, 160–250 μm, 250–355 μm, 355–450 μm, 450–500 μm and >500 μm), using an analytical sieve shaker (Retsch, AS 200). Sieves with these aperture sizes were selected based on dust particle size data from previous work (
Dust properties
The physicochemical properties of the three dust samples used in the wind tunnel experiment are summarized in Table 1.
Conclusions
The proposed CFD model was able to predict the dispersion of abraded maize seed treatment dust in an air flow. The model was validated with wind tunnel measurements. It was demonstrated that the irregular physicochemical properties of seed treatment dust, including the microstructural information, need to be implemented in order to achieve accurate predictions. This work is a necessary step towards the simulation of dust drift during sowing in field-realistic conditions.
Acknowledgements
The authors greatly acknowledge the financial support of IWT (Agency for Innovation by Science and Technology, Flemish government) for this research (project IWT 100848). Chemical analysis was carried out by M. Stähler (JKI) and the wind tunnel experiment was supported by P.T. Georgiadis and A. Herbst (both JKI).
References (30)
- et al.
Predicting drift from field spraying by means of a 3D computational fluid dynamics model
Comput. Electron. Agric.
(2007) - et al.
The assessment of dust drift from pneumatic drills using static tests and in-field validation
Crop Prot.
(2015) - et al.
Modelling pesticide flow and deposition from air-assisted orchard spraying in orchards: a new integrated CFD approach
Agric. For. Meteorol.
(2010) - et al.
A review of dispersion modelling and its application to the dispersion of particles: an overview of different dispersion models available
Atmos. Environ.
(2006) - et al.
Mechanism for the differential toxicity of neonicotinoid insecticides in the honey bee, Apis mellifera
Crop Prot.
(2004) - et al.
Intersections between neonicotinoid seed treatments and honey bees
Curr. Opin. Insect Sci.
(2015) - et al.
Indoor assessment of dust drift effect from different types of pneumatic seed drills
Crop Prot.
(2014) The Rosin-Rammler particle size distribution
Resour. Recov. Conserv.
(1980)- et al.
Spring honey bee losses in Italy
- (1994)
Honey bees, neonicotinoids and bee incident reports: the Canadian situation
Pest Manage. Sci.
Quantitative 3D shape description of dust particles from treated seeds by means of X-ray micro-CT
Environ. Sci. Technol.
Training system dependent optimization of air assistance and nozzle type for orchard spraying by CFD modeling
Aspects Appl. Biol.
Numerical analysis of the effects of wind and sprayer type on spray distribution in different orchard training systems
Bound.-Layer Meteorol.
Spray deposition profiles in pome fruit trees: effects of sprayer design, training system and tree canopy characteristics
Crop Prot.
Cited by (14)
Analysis of dust diffusion from a self-propelled peanut combine using computational fluid dynamics
2022, Biosystems EngineeringCitation Excerpt :As summarised in Table 1, the wind speed at the inlet face of the wind tunnel was set as the forward speed of the combine, which was 0.64 m s−1, and the wind speed at the dust outlet was 6.13 m s−1. The other areas were set up as no-slip walls (Devarrewaere et al., 2016). An unstructured mesh was adopted for the computational domain.
A wind flow pattern study using CFD: Why palm trees, not coconut trees resist against wind?
2021, Materials Today: ProceedingsCitation Excerpt :CFD models are developed to study the simulation of air velocity inside the tree canopies [4]. Dust dispersion from a pesticide preserved maize seed is studied using CFD and wind tunnel [5]. The laser scanning method is performed for calculating the wind velocity due to reduction through tree windbreaks and study on transpiration on plants grown in a greenhouse under water restriction is studied using CFD [6].
Eulerian-Lagrangian CFD modelling of pesticide dust emissions from maize planters
2018, Atmospheric EnvironmentCitation Excerpt :In the case of the multiple air outlets of the Gaspardo planter with deflectors, the dust emission rate was distributed over the deflectors according to their airflow rates. The physicochemical properties of the abrasion dust were measured experimentally (Foqué et al., 2017a, 2017b) and implemented in the CFD model according to previous work by Devarrewaere et al. (2016). Full technical details can be found in that publication.
Health and Safety Effects of Airborne Soil Dust in the Americas and Beyond
2023, Reviews of GeophysicsAnalysis of Dust Emission Characteristics of Peanut Whole-Feed Harvesting Based on Total Amount Collection Method
2022, International Journal of Environmental Research and Public Health