Note: It doesn't matter if you do it yourself or hire a worker for this to count. However, it must be done on a field you own, hired jobs do not count for this.This is a simple achievement it just takes time. Just grab your favorite tractor, put a cultivator on the back and go to town on a field you own. The bigger the cultivator, the faster you can get this done. It is faster to rotate through the cultivating, sowing, fertilizing and harvesting on the same field so you are working on the achievements for all 4 instead of doing one group at a time.
You can make it less a chore by buying a big field and hiring a worker then walking away while your minion does the work. You may have to repeat this a time or two depending on the size of the field you use.
You should also get this while completing this one.
You will get this naturally as you go for this one.