Mom has been busy sowing wheat--we plant winter wheat. My sister wanted me to post a few pictures of the process.
Mom pulls Dempster drills behind the tractor. If you look closely, you can see that the drills are really quite simple (I'm sure mom would say otherwise as she has had several chain issues this year.) A drive chain on the axle turns a rod that is inside the drill boxes. That rod turns and pushes the wheat into a hole in the bottom of the drill box. The wheat seed then travels down a tube that deposits the seed right behind a drill "shoe" that has made a small furrow in the ground for the seed. The press wheels are positioned behind the shoes to cover the seed. You can make adjustments on the drill that help control the amount of grain flow.
This is the front of the box. You can see the tubes coming out of the bottom--the grain travels down these.
This is a picture of the drill shoe. You can see that it makes a small furrow. The press wheels are in the background. I'm not sure why they call it a shoe--it's a very small sweep.
Sadie was excited this summer when we saw some of Leonardo da Vinci's machines at a museum, because she recognized the drive chain from the drills.
Originally, farmers might have only pulled one or two boxes behind their tractors, depending on the side. You can see that mom has 5 hooked together. We have a drill carrier to move the drills from field to field. Mom backs it over the drills (that are unhooked from the tractor), chains the drills to the carrier and lifts them up to transport. I'll try to get pictures of this soon. She has a grain truck that she carries the seed in. It has a small auger in it that she uses to fill the drill boxes. When planting, you have to make sure that all of the chains and rods are turning, otherwise you aren't sowing any seed. You also have to check you boxes and keep them full. Mom has been doing this enough to know about how long she should be able to go before filling the boxes.