Going from collected to clean seed takes more effort than you would think. Namely, lots of big fancy of toys. Last Wednesday we visited the ISU Seed Science Center to learn about the art of seed conditioning. We were to condition (i.e. clean) some Cercis canadensis seeds to prepare them for seeding in a few months. Since Cercis canadensis is a legume tree, the seeds are produced inside seed pods, which must be removed.
Doing this job by hand would likely take the entire semester, so we enlisted the aid of large machines. Sadly, it seems like the conditioning lab has not received funds to update their stock since the industrial revolution. Here is a list of all the equipment we used to clean Cercis seeds.
Step 1: The Aerator uses wind and gravity to separate pods from twigs and other larger debris. The heavier pods fall into a separate slot than the lighter twigs.
Step 2: A Brushing machine collects (mostly) seed on a wire mesh cylinder after threshing seeds form their pods.
Step 3: A Rotary flat screen helps remove most of the trash produced by the Brushing Machine on a vibrating screen.
Step 4: A second trip down the Aerator removes additional debris from the sifted material.
Step 5: An Air-Screen Cleaner further removes light contaminants. It looked like a popcorn machine with all the Cercis seeds flying inside a glass chamber.
Step 6: A Color sorter removes dark or discolored seeds which might be diseased or otherwise damaged. This was my favorite one.
At the end of it all, the professor commented Cercis is one of the easier seed to clean. I can't imagine how much more equipment is required to clean Vernonia seeds next week!