The Dust Catchers

Bee Health

Treating seeds is an art. Under no circumstances should the substance used to dress the seeds – which protects the plant from pests at germination and in the early growth phase – be allowed to enter the environment as dust when the seeds are sowed. A tough goal, but an ambitious project is aiming to achieve just that. Its name is its aim: “Zero” Dust.
Bees have to be safeguarded from direct contact with plant protection products. Together with Crop Science, Bayer Technology Services has developed an array of solutions to keep dust generation to a minimum during seed treatment.

One of Dr. Carsten Conzen’s favorite films doesn’t have much of a plot. It is an animated film that shows a bowl in which grains of rice move. Some of them are sprayed with dye. Some aren’t. This goes on for a few minutes, then the film comes to an end. “Well?” says Conzen. “Isn’t that fantastic?”

For those who know this material, what may seem to be rather mundane to the untrained eye actually represents a great leap forward on the path to optimized seed dressing. Dressing means that the seeds are coated with a plant protection agent prior to sowing. This keeps both seeds and plants safe from the very start. And the specialists agree that very little of an active substance is needed to have a very big impact.

They are similarly in agreement that treated seeds have to be handled with extreme care, because the layer of active substance coating the seeds has to stay in place and not be rubbed off. Otherwise there is a danger that the substance could be released into the environment in an uncontrolled way, and that is something that has to be avoided because it could potentially have a negative impact on bees and other beneficial insects.

For Bayer, this was the starting point for a comprehensive project comprising a large number of individual measures: “Zero” Dust. Under this rubric, a wide variety of possibilities for large-scale dust reduction were put forward, analyzed, tested and finally put into practice: from “SweepAir” – a kind of “field vacuum cleaner” – to the use of polymers to improve the adhesion of the seed dressing. “The various ideas are certainly at different stages of maturity,” observes Dr. Antoni Mairata, who is leading the project on the Bayer Technology Services side. “But with some of them, we have come a long way forward.”

With the modeling of the entire seed dressing process, for example. Which brings us back to Dr. Conzen’s favorite film. The expert, who is responsible for polymer technology and modeling at Bayer Technology Services, now has a large collection of very similar films. But if you look closely, you begin to notice crucial differences. Sometimes the grains move around in the bowl with practically no disturbance at all, and other times they are stirred up quite considerably. Sometimes the grains are colored immediately, sometimes the process takes place relatively slowly.

“Because we promote bee health, weare grateful for all the solutions that BayerTechnology Services delivers.”

Martin Gruss

Head of SeedGrowth, Crop Science

This is largely dependent on the design of the seed-dressing machine: With one, the plates that break up the evenness of the motion are attached near the top. With another they are attached at the side. Sometimes there are many of these “spoilers,” sometimes only a few. And when the design changes, so does the dressing of the seeds.

“You can compare how much of the seed hasn’t yet found its way into the spray zone within a given period of time,” says Conzen, explaining what we are seeing on the screen. “You can see exactly where certain zones haven’t yet been mixed.” Even the transfer of the dressing product from one seed to another can be visualized.

These different seed-dressing machines, however, only exist on the computer. And although we are only looking at virtual seeds, we know precisely what effect a particular apparatus design will have on the quality of the dressing. “The computer modeling, when coupled with the depth of experience brought to the table by Crop Science, allows us to understand the dressing process inside out, and to optimize it by making changes at the right places,” Conzen explains. From the scaling of planned treatment facilities to changes to existing machines – with the computer, all sorts of questions can be answered.

And this knowledge goes directly to Crop Science and to its own manufacturer of seed treatment equipment in the United States. “Our recommendations, of course, draw a great deal of attention there, because the specialists can immediately see which solution is the best, and how they can most easily achieve the desired result,” says Conzen. “All of it without having to put a lot of time and expense into building test machines.”

Seed treatment specialist: Dr. Carsten Conzen
Seed treatment specialist: Dr. Carsten Conzen. The glass containers display brightly colored seeds.

All of this, however, really comes as no surprise, because the software that makes this kind of modeling possible already exists, though it comes from a completely different field: Bayer Technology Services originally used it to optimize the feed behavior of polymer extrusion equipment. As Conzen points out, “That’s what is so remarkable, that so much knowledge is available in this company. You just have to use what’s already there.” This is happening not only with plans for new seed treatment machines – so-called “tuning kits,” also computer generated, will also be made available. These allow significant optimization of existing machines.

Precise knowledge of the processes at work in a seed dressing machine also leads to significant improvements in terms of reducing dust: “We are now able to assess exactly what forces are at work and whether they will lead to avoidable abrasion and dust.”

Independently of the seed dressing itself, improving the drying process has also been a focal point for the experts. The idea of drying the seeds during the dressing process was proposed.

This is known among experts as In-Bowl-Drying and involves hot air being directed into the bowl of the seed dressing machine. It causes the evaporation of large amounts of water and increases the space available for the dressing substance itself. Mairata: “Like this, we are able to increase throughput substantially.” A big part of the challenge was ensuring that the hot air was passed through the seed perfectly evenly. This was achieved using a special metal plate with specially designed gaps. And again, it’s no coincidence that a similar apparatus has already been used in the past – for a pharmaceutical in the field of tablet drying.

But how do you know, exactly, when you have reached the right point to end the dressing process? This point is influential in determining how much dust is likely to be produced when the seed is sowed. If the seed is too moist, the individual grains can stick together and can’t be sowed as desired out in the field. But if they are treated for too long, it can lead to an increase in the amount of abraded dust.

For this reason, a specially qualified employee constantly stands beside the basin in which the seed is being dressed. This person, because of their long experience, can hear the precise moment when the sound changes, and that is the signal for the drying to stop. This results in the dressing adhering to the seed as optimally as possible. Tests have shown that stopping the process ten seconds too late can mean up to 30% more dust.

But, according to the experts in process analysis technology at Bayer Technology Services, this process could be improved even further. This was a job for application engineer Reinhard Gross and his team. Gross proposed relying on a sensitive microphone rather than trusting the human ear. But in an environment that generally tends to be very loud, putting this idea into practice was no easy task. Two years have now passed since the inception of the project: the problem has been solved and a patent issued.

“For us, however, it was clear from the start that we were focused only on the issue at hand,” Dr. Mairata explains. The aim was also to come up with a technology that Bayer’s competitors would also use. At the end of the day, it comes down to ensuring that less active substance enters the environment, not just for Bayer, but across the board. Still, Mairata admits, “It is particularly satisfying to work for a company that does so much to reduce abraded dust.”

Will it ever be completely avoidable? The separate effects of the individual parts of the “Zero” Dust project can’t simply be added together, stresses Dr. Jens Uhlemann, who heads the Formulation & Crystallization group at Bayer Technology Services. But he has no doubts: “I am convinced that we still have some good ideas to present in this area.” After all, Bayer Technology Services has such a broad base of expertise it can draw on “that we really can tackle all aspects of the subject,” says Uhlemann. And how many firms can claim that? “Frankly, off the top of my head, I can’t even think of one.”

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