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<br />fleeD :>ercolation <br /> <br />. <br /> <br />. <br /> <br />12 <br /> <br />This is trri~ation water that moves on below the cron root zone. Excect <br /> <br /> <br />for that amount needed for leachin~, it can be assumed to oe caused oy excess <br /> <br />irri t"'a ticn . <br /> <br />The SCS renort is based on deep oercolation unit values of 0.32ac. ft. <br /> <br />ner acre ;Jer year for "ryresent condition" J anproximately 0.36 for "future <br /> <br />without" and 0.20 for "future with". A USER test on a ,'ravity irri:c;ated field <br /> <br /> <br />of alfalfa showe~ a deep oercolation of 1.24. Another field showed 0.83. And, <br /> <br /> <br />three others showed zero, with one bein~ all sorinkler and one partially sorinkler. <br /> <br />In reviewin~ other SCS salinity reports, the followinq values anoear to <br /> <br />have been used. <br /> <br />Reoort <br />Grand Valley <br />Uinta <br />Lo'.er Gunnison <br />~oana Valley (Vir~in) <br /> <br />Ac. ft./ac./:rr. <br />(acres treated) <br />Present Condition Future with Condition <br /> <br />0.42 0.22 <br />can not identify <br /> <br />0.30 <br />1. 78 <br /> <br />0.17 <br />0.34 <br /> <br />~eep oercolation values are shown for the 18 farms evaluated in the <br /> <br /> <br />Grand Valley unit durin~ 1982 in a renort nreoared by Goloraco State university <br /> <br /> <br />for SCS. Fifteen farms had imoroved furrow irri,ation systems and three did not. <br /> <br />In the fifteen that did, it was obvious that some were not tr'lin~ to manace their <br /> <br /> <br />~ater in accordance with recommendations. The overall avera~e for the fifteen <br /> <br />'nas 0.7 ac. ft. ner ac. ner yr. If four farms were dro~ned out, the avera-;e <br /> <br />becomes 0.30. For the three unimnroved systems, the avera~e ''''s 0.97. <br /> <br />Therefore. for "KRK water budc:'etn it is assumed that the "nresen condi ticn" <br /> <br />is 0.40 for surface systems and 0.20 for sprinklers; for the "future \Jithout" <br /> <br /> <br />0.45 for surface systems and 0.30 for sprinklers; and for the "future '..,i tl1" <br /> <br /> <br />0.40 is used for unimoroved surface systems, 0.30 for imoroved surface systems, <br /> <br />and 0.20 for sprinkler systems. SCS uses an 0.20 for all improved work in the <br /> <br />"future >rith" condition. This is based on a 10"\ leachin<T fraction. This fi~e <br /> <br /> <br />is iesirable, but it is questioned that the 7~, of farmers narticioatin~ in the <br /> <br /> <br />nro~ram will actually meet this ~oal unless there is some added financial incentive <br /> <br />included in the nroa,ram for turnin~ the water off at the ri~ht time. This means <br /> <br />that my use of the 0.20 value can also be 1Uestioned without an incentive. <br /> <br />001512 <br />