The widely used centre pivot irrigation systems create fallow corners marking the difference between the economic logic of irrigation technology and the grid structure imposed on the landscape.
On a typical “quarter section” in the American mid- and southwest, tessellating pivot circles will leave up 15 percent of each field thirsty.
Additional corner swing systems can be installed but are expensive and are generally used only for valuable crops. The result is a delicate equation that balances land value, potential yield without irrigation, water availability, and crop prices.
These corners are sometimes leased from neighbours to grow less thirsty crops or graze cattle, or are advocated by ecologists to restore complexity by providing biodiversity and movement corridors in a simplified landscape of monoculture crop circles.
From Edible Geography