Tilling a garden in the Dakotas, maybe loam / silt / clay ? I don't know. How do I prevent clumps ? Even if I make 10 passes with the tiller, I've still got rock hard clods. I'm using an old JD 112 with a belt drive 40" tiller. What if I wait until the ground drys out more before tilling ? The soil produces fantastic potatoes, corn, tomatoes and cucumbers.