Ranges and pastures of the Southern Great Plains and the Southwest

TitleRanges and pastures of the Southern Great Plains and the Southwest
Publication TypeBook Chapter
Year of Publication1973
AuthorsHerbel C.H., Baltensperger A.A.
EditorHeath M.E., Metcalfe D.S., Barnes R.F.
Book TitleForages, the Science of Grassland Agriculture
PublisherThe Iowa State University Press
CityAmes, IA
Keywordsdescription, Great Plains, pastures, ranges, Southwest
AbstractThe southern Great Plains and the Southwest often are called "Big Country." This not only refers to the size of individual holdings but the sparseness of urban centers. Annual precipitation averages less than 250 mm in the lower elevations of Arizona, New Mexico and western Texas. It ranges up to 750 mm in the eastern portions of the southern Great Plains. The precipitation not only varies greatly within and among seasons and years but also among locations separated by only a few kilometers. About 70% of the average annual precipitation occurs during the spring-summer period in the Great Plains. In western New Mexico and southern Arizona the growing season precipitation occurs during the summer and the spring period normally is very dry. The entire region is frequently plagued by drought. During a prolonged drought, the Great Plains may take on a desertlike appearance. The region may also have high winds during some periods; coupled with a reduction in vegetation and cover due to drought, this results in considerable wind erosion. The average annual evaporation ranges from 2160 mm at Oklahoma city to 3050 mm at Yuma, AZ. The frost-free period averages about 180 days in the northeastern part of the region to 340 days in the Yuma area. Elevations in the southern Great Plains vary from 200 m in southern Texas to 1200 m in northeastern New Mexico. The parts of Arizona and New Mexico considered in this chapter are desert or desert-like basins interrupted by mountains. The entire region is dissected with rivers and their accompanying floodplains. The soils are highly variable.