Quality Versus Quantity While Processing Seed

- Jon Moreland

Those words are applicable to many things; relationships with friends & family, the food we consume, communications at work or how about seed? Right… seed, that is where the topic comes up most frequently for me (note to self: check work-life balance).

Seed quality and processing capacity are two of the most fundamental parameters to measure any seed conditioning facilities or equipment. Sometimes the two functions are harder to quantify than they seem, where it is not only hard to determine true flows, but equally hard to determine vigor of seed visually. What makes things even more complex is that there is, almost without exception, an inverse relationship between quality and quantity while processing seed.

Consider the pre-cleaner and fine cleaner. Yes, capacities can be pushed to extreme levels, but as they are, particles being sized begin to override the holes providing the screening function. The seed is never presented to a screen hole to determine if it should pass as accept or reject. The good operator knows this is why he has good seed losses in the cleaner scalpings, or still fines in the good seed sample. Why do manufacturers state different capacities for the same machine? Why does the same model have different stated capacities for fine cleaning, rough cleaning and pre-cleaning? Because those terms reflect different quality levels of “clean.”

An adept operator will tell you that pushing capacity will also negatively affect quality on your density separation equipment. On a gravity separator, capacity adjustments typically include feed rate and end raise. Inevitably to create increased capacity you have to create more and faster flow across the deck. As the seed is exposed to the forces of the machine for less time, quality begins to diminish.

Optical sorters too can be affected by pushing capacity too high. As product flows increase through the optical array, if blemishes are covered up by other seed, the optics don’t detect them. If optics do pick up blemishes in heavy flows, typically the ejectors will push additional residual losses of good seed into rejects.

With any of these machines there is always a sweet spot or range to operate. My inverse theory only fails in very light capacities where the machines won’t operate at all. Consistent flows where particles react against one another to stabilize the mass will always create reliable qualities.