If you didn’t see them last week, scroll down to Law of Supply and Demand Lesson Plan and check out the tires on the tractor, cart, and combine.
What do you think? Pretty big, huh. Well, today you will learn why farm equipment needs to have such large tires!
To begin, let’s try a super simple soil experiment. You will need three things.
1.) Either some soil or sand
2.) Your finger
3.) Your hand
Like I said, super simple soil experiment. Let’s start with the soil or sand. All you need is a pile. It can be in a pot, in the bag you bought it in, or in the sandbox, but you need a pile, not just the ground in your backyard.
Next you need your finger. Got it? Good. Poke your finger down into the soil.
Did your finger go down into the soil? Unless your dirt is really a rock, your finger likely went in all the way. Now, spread your fingers wide and place your whole hand on the soil. Push down again.
Unless your soil is more like oozy mud, your hand probably made little more than a print. Compare the two “holes” you made. Do they look like mine?
Your finger made a much deeper hole, didn’t it. And this hole was not made by taking soil out of the pile, but by pushing it in. Soil being pushed down is called “compaction.” Compacted soil is hard. It has little room for air, water, or roots to grow. Compaction is bad!
Unfortunately, compaction is also a reality. Farmers must drive tractors, combines, sprayers, and other equipment over the ground. So they have to do something about it. Historically farmers have solved this problem by plowing their fields. Horses pulled the first steel plows through the ground hundreds of years ago. The metal knife cut into the ground, breaking the soil into pieces. This helped with compaction, but can you guess what it hurt? Erosion. When the dark brown dirt was turned over and the seed bed was smooth even a small rain could wash away the soil into ditches, streams, and rivers. Big rains could wash away entire portions of a field.
So today many farmers use a method called “no-till”. Instead of plowing the ground farmers plant seeds into dirt that was left just as it was after last year’s crop was harvested. Roots from the old plant hold the soil together, preventing erosion, BUT the soil was again compacted.
Engineers, Scientists, and others worked with equipment companies like Case IH and John Deere to make new tires that would cause less compaction. They used the same idea you just did with your finger and hand. Old tractor tires were small and thin, sort of like your finger. New tractor tires are wide and gigantic, sort of like your open hand! New tires were made of rubber, instead of steel and farmers often let some air out of the tires to make them squash even more, the way a balloon will squeeze flat when it is almost out of air. Some tractors and combines even run on tracks, like a bulldozer, which lessens compaction even more.
Farmers care about the earth and the soil on it because they understand how important healthy soil is to happy eating! And who knows? Maybe one day you will become a scientist and help create new technologies that will allow farmers to take even better care of our world!