Each spring, roughly 100 UC Davis students spend a quarter repeatedly tilling and plowing a 10-acre field on campus.

“If you come at the end of this quarter, this field has been worked so many times the soil is like powder,” said lecturer Mir Shafii, who teaches several Applied Biological Systems Technology classes, including the ever-popular ABT 49: “Field Equipment Operation.”

Tractor driving.

“When they actually are a student in the most famous ag school in the world, they like to say, ‘Well, I drove tractors when I was there and I know how to do it,’” said Shafii, a native of Iran whose family farm there grew mostly wheat and grass.

The once-per-year ABT 49 inevitably has a long waiting list, and Shafii — who's been working at UC Davis for 25 years and teaching the class for five — often has to let in seniors who need the class to graduate.

The students learn to operate a stable of about a dozen tractors, each with totally different controls. Some are fresh-off-the-lot donations, while others have been on campus since the 1960s.

Dateline’s Cody Kitaura sat down with Shafii to talk with him about his unique job:

You said this is a very popular class. Do you think it's people who are actually going to use it or just want to take it for fun?

Half and half. I have students from fields that are not at all related. I have a student that took ABT 15, 16, 52, 49, and he is in political science.

Do you have any funny stories about kids getting the tractor stuck or something?

It will not be funny if they get stuck with the tractor, because tractors don't think. So definitely we are very careful about students not getting involved in anything that is not safe around the tractors. Luckily for these several years I've been here we haven't had any problems or accidents. …

There have been some occasions where I have seen students putting the tractors in the wrong gear, which is a higher gear, without knowing. … So, if you put it in the high range and you don't know it's in the high range, all of a sudden the tractor will start rolling, going so fast. And the field is not level, then you start going up and down, up and down, especially if you go against the rows.

A lot of these tractors are pretty big. Is it intimidating or scary for the kids when they first start driving?

Our smallest size of tractor is about 40 horsepower; our biggest sometimes goes over 100, but this year we have a tractor that has 300 horsepower. A big tractor like that one, even the size of it would be a little scary. For that one, we do not let the students sit alone inside. Those tractors have a trainer seat. You know that tractors have been designed for only one person to drive. There's no way that you can have a passenger sitting anywhere — there's no seat. So that one has one for the driver and one for the trainer.

How do you maintain all the tractors?

Maintenance is scheduled like cars. If you do all the scheduled maintenance properly, based on the hours of work on the tractor, that tractor will be safe and it will be for years.

Is the maintenance done by staff?

The students at the end of the quarter change the oil, filter, transmission fluid, coolant, fuel filter. All of the maintenance, if it's needed, will be done by the students at the end of the quarter, and we have a record of it for the next season.

What's the hardest thing for students to learn?

I think using a clutch. … When I start a class, in the first lab I ask how many have used a clutch: some of the classes, out of 16, maybe only one, or none.

So the oldest one is a tractor from the ’60s?

Yes. Definitely if you have newer tractors, more of them, that would be good, but it's limited.

What's the newest?

The newest are 2014 — we have two of them.

That's a pretty big range.

Yeah. We use whatever we have. Definitely it isn’t worth it to have a number of tractors parked in here to use only one quarter a year, because this course is only taught in the springtime because of the season. Rain is one of the problems that we can get if you teach this course because we're working in the field continuously. … A few years ago in the middle of the work in the field, it would start raining and we would all have to rush to the building. Sometimes we even had to close the lab for a couple of days. And those days we were working inside on the tractors' maintenance.

So you don't have them drive out there when it's raining.

If you drive in a rainy condition, most of the tractors have some sort of cover but they don't have a cab. So that would not have been comfortable for them, and if the field gets wet, then they might get stuck in the field. So we try to get out of the field before that.