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<br />~. .., <br /> <br />C/' <br /> <br />. <br /> <br />DEPARTMENT 'OF PUBLIC WORKS <br /> <br />219 <br /> <br />')f <br /> <br />.' <br /> <br />yield mily be 10'iVin spite of an: unusually wet spring. On the 'other <br />hanel-if the spring be' unusually -dry, a -low yield may result in.spite <br />of:"awiet fall. The .falland 'spring seasons:mll.st work together if a <br />I . <br />good yillld is to be obtained. <br />. Aconiplete . analysis of wheat yields and rainfall'in Adams and <br />PhelpsCountie3 which wlUnot be' presented here shows that low yields <br />are' obtained when either or both the 'fall and spring seasons' are dry, <br />and high yields 'are obtained when batYl fall' ang spring arewet. Medium <br />to 'high'wMat,yieids; a:veragirtg 18.6 bushels ha\-e beer; .obtained in' <br />nin~ 'cases in 'ten when the to'tal effectiverainfa:ll 'in fali and. spring <br />wa's 12.66' inch~s, distributed'. as approxirilately4' inches in fall and' 8 <br />inches' inspring,'6r vice versa. Low to mediuni yields, averaging 10.6 . <br />. bushels have been obtained in nine cases in ten when either. the fall <br />or spring rainfall varied from less than 3 inches' in fall with a spring' <br />ramfall of over 8 inches,' to more than 8 inches in the fall With a <br />spring rainfall . under 2 inches. The quantity of water required to <br />. supplement seasons of such types of in'adequate rainfall and convert <br />them into seasons of adequate rainfall where the chances are nine to <br />ten that yields will be 8 bushels better, is approximately 4 inches. <br />Thus it appears for whealt, just as for corn, that for each inch of sup- <br />plemental water applied in season, approximately 2 bushels of wheat <br />can be obtained. Years in which either fall' or spring precipitation or <br />both are inadequate. and will requiTe supplemental water to proouce <br />an. average yield of 18.6 bushels' per' acre, have occurred approximately <br />half of the time . during the past twerlty years. <br /> <br />f - ~ <br /> <br />Supplemental Water. <br /> <br />Supplemental irrigation is the practice of adding to the soil <br />sufficient water to carry the crop thru periods of drought and to <br />make up the difference between' the crop requirements and the <br />rainfall. The water may be applied either before the Crop is seeded <br />and. held' in storage in the' subsoil, or .as a direct application when <br />the crop is growing. The fact that the deficiency of rainfall can <br />in a large measure be met by water in storage was first observed by <br />the farmers themselv(es. They noticed that in those years when they <br />had a considerable carry-over of water from the previous year, or <br />when spring rains wet' a considerable column of soil, they were much <br />more certain of satisfactory yields than in the years when the <br />seeding period found the entire soil dry. This has been the experience <br />of all farmers in the Grea..t Plains region. <br /> <br />The protection against drought thru water in stora,ge in. the soil <br />. . has been further. borne out by the experience of the farmers who <br />are practicing what is called "Dry Farming," when they summer-till <br />and store water in the soil. At North Platte Experiment Station (3), <br />it was found that an "abundance of water in the subsoil is a great <br /> <br />,-,.- .- <br /> <br />, <br />It. <br />I. . <br />