Atomicrops

Unfortunately I believe that this is a luck based achievement. As far as I know, the Megaton Tractor can not be bought from the store, and has to be found in one of the biomes. Other than that, this achievement is pretty simple. Simply make sure that your tractor has preferably 2 charges on it (in case you miscalculate it's health) and shoot a boss until it's a few hits or so away from death and drop your Megaton Tractor on them.

Year Recommendation: 1
Playing this on year 1 will give you the best opportunity to get money and good guns to be able to explore the other biomes and find the tractor.

Edit: I got this achievement shortly before the Doom and Bloom update came to console.