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<br />xiv <br /> <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />uniformity can be achieved with proper design management, <br />maintenance and tailwater runoff recovery facilities. <br /> <br />2. Flood/Border/Bench methods - a variety of land preparation methods <br />are used to create a system of water containment areas (basins, <br />paddys, benches, etc.) with el evated "borders", whi ch are then <br />flooded with water. Close growing crops such as small grains, <br />alfalfa, improved pasture grasses, etc., are usually grown in the <br />border type systems. Efficient water use and uniformity of appli- <br />cation requires some leveling or grading of most borders to achieve <br />level borders (from side-to-side) and designed grades from upper to <br />lower ends. These systems are most effective on heavier soil types <br />with very modest slopes. So called "dead-l eve I" systems are <br />leveled from both side-to-side and end-to-end, with the objective <br />of uniform distribution and infiltration of water on heavier soils <br />or where leaching of salts is necessary. <br /> <br />3. Basin/Conservation Bench/Terracing methods - relatively recent <br />innovations to optimize use of natural precipitation in conjunction <br />with supplemental irrigation (particularly pre-plant irrigations), <br />or on areas where insufficient water is available for full scale <br />irrigation. The "basin" technique consists of modified tillage <br />equipment which erects small mounds of earth (dikes) at regular <br />intervals in each row, creating basins which hold the water in <br />place until it can percolate into the soil instead of being lost <br />as runoff. The conservation bench method is a system of level <br />benches, with contributing (watershed) areas usually in a 2:1 <br />ratio (contributing area is twice the area of the level bench area). <br />The bench leveled areas are created in conjunction with forming <br />parallel terraces on the down-slope side of each bench. An alter- <br />native form of this practice, called "bench terracing", eliminates <br />the undisturbed contributing areas by moving the terraces closer <br />together so that the entire area between terraces is bench leveled. <br />These systems are being applied on significant acreages in the <br />southern High Plains area on slopes of greater than 1 percent <br />(e.g. on slopes around Playa lakes). <br />