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<br />no;]:, ,Alj <br /> <br />- 6 - <br /> <br />If we aSSUMe that 95% or 6Cj,980 irrigated acres of corn and <br />sorghum for grain in the Blue River ~a:in are not reaching yields <br />of at least 130 bu. pp.r acre, but have the possibility to do so with <br />fertilization, then additional water will be consumed. This demand <br />may be tra:1slated from I" per acre i:1to $0,331 additional acre feet <br />of water potentially needed an~u81ly for the area. This estimate is <br />conservative because 8 few irrirators are already reachi:1g 180-200 <br />bushels of corn per acre. I'lo data 0:'1 water use by the additional <br />yield increment is available. It may be possible that in the next <br />10 years the need could expand. it would be n matter of conjecture <br />whether an increazed amount of water will be cO:'1sumed by the higher <br />crop yields or whether advances in technology and (enetics will in- <br />crease efficiency of the water consuned. <br /> <br />Alfalfa is rrow~ o~ approximately 22.146 acres in the Basin. <br />According to ~stimates, yields are about 5.0+ T per acre represent- <br />ing a current need for about 25 inches of water per acre. If yields <br />were improved to the 6-8 T level an additional 5-15 inches of water <br />per acre Hould be needed. Assuming all alfalfa acres were to increasE: <br />to approximately a 7 T yield. a need for 10 addi tional inches of wa- <br />ter per acre might reasonably be expect~d. Tra~slated, this could <br />mea~ a demand for 18,455 additio~al acre feet fer the 6rowing of top <br />yielding alfalfa crop. <br /> <br />"ateI' uses on rer:1aining irrigated crop acreages of silage crops. <br />sugar beets, soybeans, etc. can be expected to increase slightly as <br />varieties and yields improve. ;!o evidence, hot-lever, has been ob- <br />tained to e~able estimation of added water needs for those acreages. <br /> <br />POTE:~TIAL l-.IATER SAVING - DISC!JSSICN <br /> <br />Although good irrigation ma~agement practices are at a moderate <br />level of use in the Blue Eiver Fasin ad1itional water savi:'1g can be <br />achieved on many irrigated farms. It is important that correct irri- <br />gation land levelling practices be continued. HOt-lever, the us~ and <br />improvement of the follot-li~g irrigation management practices will <br />assist in additional water saving. <br /> <br />1. Pipe conveyance of water from supply to field distribution <br />point. <br /> <br />2. Soil mcist~e sensing deviceG for irrigated fields. <br /> <br />3. Irrigation water runoff-recovery and reuse systems Ior all. <br /> <br />4. Adequate design of sumps and reservoirs to minimize evapor- <br />ation. <br /> <br />5. Tillage practices which ~inimize soil evaporation and re- <br />duce compaction. <br /> <br />'The i!'rigatio~ water runoff recovery and re"Jse s~rstem at this <br />time a~~ear to offer the ~reatest and Most feasitle potential for <br />total basin wide saving of the availaole water supply. For this <br />reason the following estimates are offered for consideration. Tab~ <br />4 estimates are based o~ the goal ~f 90~ far~ irrigation efficienc' <br />and these assur.lptions: (8) recovery and reUS8 systems for s'.;rfac~ <br />irrigation and use of sprinklers ~ill reduce irrigation runoff to <br />