Dryland farming, growing crops and raising livestock with limited precipitation, is a consequence of semi-Arid climates. Because dryland farming systems depend on rain and snow for their necessary moisture they differ from Arid zone systems where irrigation is necessary and from humid zone systems where moisture is adequate or surplus for crop growth. Dryland farming occupies the largest areal extent of agriculture found in semi-Arid regions. As with many geographic definitions, the semi-Arid regions have both a physical-climatic and a cultural element in their definition. Achieving a definition that will permit identifying such areas through numerical climatic terms (physical) and relating such terms to the socioeconomic activities (cultural)
