Dryland farming is a process of growing crops in semiarid regions without irrigation. Semiarid regions often receive little rainfall during the crop-growing season. Therefore, farmers in these regions try to increase the amount of water that soaks into the soil during rainy or snowy periods. During the growing season, the roots of crops absorb water stored in the soil.
Dryland farming includes various practices that help increase soil moisture. Many farmers leave part of their cropland fallow (unplanted) each year. The fallow soil stores moisture for the following year’s crop. Instead of plowing the land, the farmer tills the soil 3 to 4 inches (8 to 10 centimeters) deep. This technique, called shallow cultivation, kills weeds, which absorb moisture from the soil.
Many farmers use stubble-mulch tillage. In this practice, large sweeps of a plow undercut the surface and kill weeds, leaving dead stalks and other plant wastes on the surface. These crop residues protect the soil from wind erosion, reduce the rate of evaporation of water from the soil, and increase the rate at which the soil absorbs water. Residues on the surface also trap blowing snow, which eventually melts and enters the soil. Some farmers control weeds with chemical herbicides rather than tillage. This technique, called no-till, no-tillage, or zero tillage, retains all crop residues on the surface.
Another dryland-farming technique is contour tillage, which is practiced on sloping land. In contour tillage, the farmer plows across a slope, rather than up and down. The tilled soil forms small furrows. These furrows prevent rainwater from running down the slope. Thus, the water stays on the slope and soaks into the ground.
Only certain hardy crops, such as barley, cotton, sorghum, and wheat, can be grown by dryland-farming methods. Even so, many farmers plant these crops as early as possible in the growing season so that the plants mature before the weather becomes too hot and dry.
Dryland farming is practiced in semiarid regions of many countries, including Australia, Botswana, Canada, China, Kazakhstan, Russia, and the United States. The largest U.S. dryland-farming region lies in the Great Plains. Researchers have improved many dryland-farming techniques and have developed new crop varieties that need little water. These improvements have increased food and fiber production in dryland-farming regions.
