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<br />. . <br /> <br />C) <br />""j-' <br />~\l <br />.,-t <br /> <br />Report to the USDI, Bureau of Reclamation <br />from Colorado State University Cooperative Extension <br /> <br />(:.' <br /> <br />BACKGROUND <br /> <br />Surge irrigation has been recognized for a number of years for its ability to enhance <br />irrigation water advance across a field. The principle involves a valve operated by <br />a motorized controller which Switches the irrigation water from one side of the field <br />to the other at prescribed times. The first application advances down a short <br />portion of one side of the set before the water is switched over to the alternate <br />side to advance the water the same distance. It is powered by a solar collector <br />attached to a battery and is relatively maintenance free. The number of cycles of <br />alternating the water from one side to the other is dependent upon the soil type, <br />length of irrigation run and the amount of water available for the irrigation. After <br />the initial alternating times (called "out times") the cycles are decreased in length <br />of time to soaking, or cutback times. At this point. the field should be wetted <br />through to the end and excess water runoff ("tailwater") should be minimized. <br /> <br />Several theories exist as to why surge irrigation works. The most accepted version <br />is that the water may continue to penetrate the soil even after the irrigation water <br />is removed from it; this may result in some soil "sealing" by breaking of some <br />capillary flow and less penetration when the next "surge" of water is applied. <br />Thus, the water may travel further down the furrow with less water applied than if <br />the water had been applied continuously. As a result. vastly improved irrigation <br />efficiencies have been realized by many irrigators and the conclusions have been iL . <br />published in several journals. , t~ \ . <br />! r I i l .' <br />\ ", \ " J <br />. " \" y , <br />/ (r 1: <br />"\~- v! . '-L_ <br />The Grand Valley is situated in west central Colorado. In any given year, about \ " <br />60,000 acres are irrigated by gravity flow water delivered through mostly unlined <br />canals from the Colorado River. The entire area is underlain by a saline marine <br />formation known as Mancos shale. Since the irrigation water is plentiful and <br />inexpensive, considerable over-irrigation occurs. This over--il"rigation coupled with <br />leakage from the unlined canals contributes about 600,000 tons of salt annually <br />from the shale through return flow to the Colorado River-drainage. Principal crops <br />are corn for both grain and silage, alfalfa hay, small grains and orchard fruits. <br />Smaller acreages of onions, dry beans and soybeans are scattered throughout the <br />valley. Production on a per-acre basis is good. <br /> <br />,\ <br /> <br />THE GRAND VALLEY: <br /> <br />, <br />\ <br /> <br />THE SURGE PROJECT: <br /> <br />One hundred twenty-eight cooperators were invited to participate in the USBR <br />sponsored surge project over the four year periOd from 1990 through 1993. The <br /> <br />2 <br />