 Since the West was settled, farmers have been turning rangeland into fields to produce food for a growing population. Many used a method called dryland farming, or agriculture without irrigation. Dryland farming is an agricultural practice that involves the use of drought-tolerant crops and banking soil moisture. It is common in areas that have a wet season, usually in the winter or early spring. In Wyoming for dryland farming to be successful, the area must receive at least 15 inches of precipitation annually, and most of this must come in the late winter or early spring as heavy wet snows. Moisture from the wet period is stored in the soil. The crops use that moisture to germinate and grow. Traditional dryland farming in Wyoming uses a technique known as strip farming. One strip of land is planted and another strip of land is left fallow. Fallow is a period of no tillage where stubble from the last year's crop is left to protect the soil from erosion. Each year the planted and fallow strips are rotated. A more modern form of dryland farming requires no tillage. Each year the new crop is planted into the stubble of the fallowed strip and tillage does not occur. From the University of Wyoming Extension, I'm Ashleigh Garles, Exploring the Nature of Wyoming.