My slash-and-burn experiment wasn't a total failure, nor a big success. I sow about 1.5 liters of rye seed. After harvesting, threshing and cleaning I got about 3 liters of rye seed. And learnt a lot. The picture is from the cleaning process - there is a bowl on the ground, and in my other hand I have a sieve. It was a winy day, so pouring the contents of the another bowl makes the seeds fall down, while the light chaff is gone with the wind. The sieve blocks pieces of rye stalk and other such stuff, so it is mostly just seeds which end up in the bowl on the ground. I then switched the bowls and repeated the process for a better result.