You need to put a clown in the dirt if you want to cultivate good crops there. Clowns act as a natural fertilizer, and this will make it super easy to cultivate any crops you could ever want in this dirt. Isn't nature amazing?
Before you can start this whole cultivation process however, you have to say bye (ばい) to the clown. Say bye to him, then bash his head in, and drop him in the dirt.