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<br /> <br />. <br /> <br />w <br />I\;) <br />o <br />I\;) <br /> <br />!NTEODUCTIQ!':l <br /> <br />Irrigated agriculture has been practiced in arid and <br /> <br />semi-arid regions of the world since the beginning of man's <br />civilized history. Supplementary irrigation during the <br /> <br />growing season is becoming increasingly commonplace in humid <br /> <br />regions. <br /> <br />The earliest known records of man's attempt to raise <br /> <br />crops using artificial application of water are found in the <br /> <br /> <br />Middle East and North Africa. The remains of wells, <br /> <br />underground collection systems, dams, reservoirs, terraced <br /> <br />irrigation works, catchment basins, aqueducts and conveyance <br /> <br />channels in the Middle East all indicate that the land once <br /> <br />supported a large population with an advanced knowledge of <br /> <br />irrigated agriculture. Today, this once verdant land is <br /> <br />largely barren and non-productive as a result of salinity <br />buildup in once-fertile valleys, salt marsh development, <br /> <br />denudation of topsoil by aeolian and fluvial erosion, sand <br /> <br />dune encroachment, and general deterioration. <br /> <br />Of the world's nations, China irrigates an estimated <br /> <br />182,855,000 acres (74,001,400 hectares), India 93,000,000 <br /> <br /> <br />acres(37,637,lOO hectares) and the United States <br /> <br /> <br />approximately 44,000,000 acres (17,807,000 hectares). <br /> <br />Irrigated agriculture is practiced on about 10 percent of <br /> <br />1 <br /> <br />~ <br /> <br />4~_,- .',__. <br /> <br />-~ <br /> <br />