Dryland farming is the practice cultivating crops without irrigation (rainfed agriculture). In the United States, the term usually refers to crop production in low-rainfall areas without irrigation, using moisture-conserving techniques such as mulches and fallowing. Non-irrigated farming is practiced in the Great Plains, inter-mountain, and Pacific regions of the country, or areas west of the 23.5 in (600 mm) annual precipitation line, where native vegetation was short prairie grass. In some parts of the world dryland farming means all rainfed agriculture.
In the western United States, dryland farming has often resulted in severe or moderate wind erosion . Alternating seasons of fallow and planting has left the land susceptible to both wind and water erosion. High demand for a crop sometimes resulted in cultivating lands not suitable for longtime farming, degrading the soil measurably.
Conservation tillage , leaving all or most of the previous crop residues on the surface, decreases erosion and conserves water. Methods used are stubble mulch , mulch, and ecofallow. In the wetter parts of the Great Plains, fallowing land has given over to annual cropping, or three-year rotations with one year of fallow.
[William E. Larson ]