Farming equipment is designed to do a lot of work but over a long period of time. It's not racing where time is of the essence. Horsepower is torque over time or how much work you do over time.

Farming equipment needs a lot of torque to move and carry tons of material but it doesn't need it to be delivered quick. So it's incredibly strong but slow paced. Which is also good, slow turning engines don't wear down as fast and are much more reliable.

That's why you can see most workhorse engines are low revving, low horsepower, but have high torque at the low end and usually are coupled with gearboxes that multiply that torque much higher still.