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"-j' t" ,': i [, 1 " ,- 1; " ~} i ~. ~. , ~ ;, ~~ 'I r, I I t '- l r t~ IV " II i ! ! I ~ 00 We may conclude that efficient surface water use for these soils ,_') requires well leveled land, proper lengths of nm, large heads of ~ water, and high demands on an irrigator's tirre. Larger field irri- C'J gation heads may be obtained by lining canal systems, putting dCMl ,_.) additional wells, oonstructing overnight storage reservoirs where C..; feasible, or rotating water arrong canal water users. Automatic' devices for changing water sets can relieve the demands on the irrigator's time. Many "water buggies" (self-propelled traveling canvas darrs in an irrigation ditch) are being used in the Valley. The short tirre that water is on the soil surface when water buggies are used penni ts 1"", applications of water and high water application efficiencies, irrespective of border ditch length. Wider than average border widths (up to 60 feet on well prepared gently sloping land) may be used as long as the water sUH;>ly is sufficient. Where a satisfactory water table level can be maintained during the crop irrigation season, subirrigation appears to be a very satisfactory method of water application with little labor input. A good system of ditches and checks and cooperation with adjacent fanrers is necessary for the success of this rrethod. Land must be leveled to parallel the water table. HaNever, when the sub declines during the irrigation season as it often does in sare parts of the Valley or during years of lCMer water supply, application efficiencies with the surface irrigation then needed are often lCM. Walker reports 1/ that in an area of declining sub, he applied only 12.25 inChes of water on potatoes by sprinkling ca:rpared to three to four tirres as much water on furrow irri- gated potatoes with 440 and 660 foot runs. Excess water appli- cation also contributes to leaching of soluble soil nutrients. Revel ving type sprinklers and water buggies are beccrning rrore popular each year in the area. As the sub becomes rrore difficult to maintain, other methods of irrigation will be necessary to obtain satisfactory water application efficiencies. Abe Relyea, Extension Agronanist, Colorado Extension Service and SCS teclmicians have been working with ranchers near Saguache on water management. Two ranchers are raising several times as much hay with intennittent irrigation per acre than they fonnerly did. winter irrigation and =ntinuous irrigation to the time of harvest had been practiced forrrerly, but was discontinued in favor of an intermittent irrigation schedule based on the needs of desired grass species. Reseeding was not done. The environrrental changes resulted in a decrease of the water-loving species and an increase in western wheat grass and other grasses. 'Ihe first year production y See reference 29 24