“Your goal is to create fracture, so the soil has to be dry enough to shatter, not smear. To see if you’re achieving this, dig between the shanks with a spade and see if the soil is loosened. If you bring up huge clods, the soil isn’t shattering and it would be better to wait until it’s drier. Straight shanks are going to cause the least amount of soil disturbance,” Presley said.

Also, keep in mind that certain areas of the field are more compacted than others, she said. Those areas might not be ready for deep tillage at the same time as the rest of the field because compacted areas tend to stay wetter, longer.

“A case in point is a recent trip I made to a producer’s farm. I observed soil shattering from deep tillage across the entire 30 inches between the shanks in the average part of the field, but in the end rows where the grain cart was driven, I dug up clods that were about one cubic foot in size, most likely because the more compacted areas were wetter.”

Is deep tillage economical? “Only if a root-limiting layer is really present, and even then this is a costly operation (because) it requires a lot of power to go deep. Deep tillage is slow-going and the implements are not very wide. As a result, deep tillage requires a lot of operator time, diesel fuel, and usually a few shear bolts!” Presley said.