Howard Audsley has been driving through Missouri for the past 30 years to assess the value of farmland. Barreling down the flat roads of Saline County on a recent day, he stopped his truck at a 160-acre tract of newly tilled black land. The land sold in February for $10,700 per acre, double what it would have gone for five years ago.

Heading out into the field, Audsley picked up a clod of the dirt that makes this pocket of land some of the priciest in the state.

"This is a very loamy, very productive, but loamy soil," Audsley said. "A high-clay soil will just be like a rock and that's the difference between the ... soils. And the farmers know this and the investors know this. That's why they pay for it what they do."