. Soil physics and management. irrigated $10,000,000 7,000,000 130,000 5,000,000 8,700,000 243,000 4,400,000 118,000 1,,000 152,000 1, 219,000 1, 216,000 16,200,000 129,000 3, 257 2oS SOIL PHYSICS AND MANAGEMENT The axea of laud that may ultimately be brought under irriga-tion is small in LX)mparison Trith the t^tal dry-land area, becausethe total supply of ^ater is not sufficient for more than one-tenthof the dry land. At present only about one per cent of the land inthe western states is irrigated. The building of such reservoirsas are given i
. Soil physics and management. irrigated $10,000,000 7,000,000 130,000 5,000,000 8,700,000 243,000 4,400,000 118,000 1,,000 152,000 1, 219,000 1, 216,000 16,200,000 129,000 3, 257 2oS SOIL PHYSICS AND MANAGEMENT The axea of laud that may ultimately be brought under irriga-tion is small in LX)mparison Trith the t^tal dry-land area, becausethe total supply of ^ater is not sufficient for more than one-tenthof the dry land. At present only about one per cent of the land inthe western states is irrigated. The building of such reservoirsas are given in the prec-eding table is extending the irrigated areamore than was supposed to be piossible a few years ago. Area and Projects.—In 1909, 13. acres of land wereirrigated in the arid states. This was an increase of S2 per cent inten years. In 1910 the projects, then started, will be capable ofirrigating ,711 acres when fully under way. The total areaincluded in the projects is 31,112,110 acres. In addition to tbe. Fig. 113. Fig. 114. FiQ. 113.—Conduit for conducting water to where it maybe used for irrigation. (U. S. Reclamation Service.)Fig. 114.—Concrete-lined canal that permits no loss by seepage. ^t. S. Reclamation above, T 24,800 acres of land were irrigated in humid areas, nearlyall of which was for the growing of rice. The United States Eeclamation Service, established in 1903,was to use the money from the sale of public lands in the arid statesin the c-onstruction of irrigation systems. Under the direction ofDr. F. H. Xewell immense projects have been started, many ofwhich have been completed, and by which large areas have beenreclaimed and added to the country as some of its most valuableassets. Sources of Water.— (a)Diversion of Streams.—^The com-mon sourc-e of water for irrigation has been the diversion of partsof streams at a height above where it is to be used and c-onductingit by means of canals, tunnels, conduits and ditches to whe
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