Characterisation of different pneumatic sowing machines

As a consequence of the acute honey bee poisoning events observed in several European countries during maize drilling, the dust drift topic has received increasingly more attention. We aimed to quantify the dust drift risk, develop reduction measures and innovate sowing techniques using an integrated experimental and modelling approach. To validate and finetune the dust drift CFD-models under development, the designs of three selected sowing machines and associated tractors were digitised. For the two pneumatic drills, the airflows around the machines and at the in- and outlet air ducts were measured. Air velocities at the outlets ranged from only 0.11 m s^-1 for the pneumatic bulk drill up to 26.1 m s^-1 for the pneumatic precision drill without deflector. The use of a deflector reduced the exit velocities to 13.4 m s^-1 as well as the air velocities around the machine. Reference tracer seeds were developed with different qualities regarding dust production in order to measure the dissipation of dust around static operated drills and in field conditions.