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Organic Matter as a Factor in Classification of the Soils of Dry Regions 1
Author(s) -
Shaw Chas. F.
Publication year - 1932
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1932.00021962002400070010x
Subject(s) - citation , soil water , organic matter , dry matter , library science , computer science , soil science , agronomy , environmental science , ecology , biology
In the regions of arid and semi-arid climates and in those regions of sub-humid climate where the precipitation is periodic with wet winters and dry summers, organic matter plays a relatively minor part in determining the characteristics of soil profiles. During the dry season when temperatures are high any accumulation of organic debris upon the surface becomes thoroughly dessicated. The components, whether pine needles, leaves of deciduous trees, herbaceous remains, or grasses, become tinder-dry and brittle, breaking readily when trodden upon or handled. By mid-summer the surface soils are thoroughly dried out and by early autumn the soil profile becomes dry to depths of 2 to 6 or more feet, depending on the depth and density of root population. During this dry season the temperatures of both the air and soil are high. Weather records show the mean monthly temperature at Imperial to be above 7o°F from April to October, inclusive, and above go°F during July and August; at Davis in the Sacramento Valley, to be between 60° and 75°F from May to October, inclusive; at Emigrant Gap in the Sierras at an elevation of 5,230 feet, to be