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Last modified
1/26/2010 12:12:52 PM
Creation date
10/11/2006 9:31:57 PM
Metadata
Fields
Template:
Water Supply Protection
File Number
8449.921
Description
Lower Platte Tri-County Project Water Demand & Power Studies
State
NE
Basin
South Platte
Date
1/1/1923
Author
Univer. Of Nebraska
Title
Report of Certain Investigations on the Central Nebraska Supplemental Irrigation Project
Water Supply Pro - Doc Type
Publication
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<br />226 <br /> <br />REPORT OF SECRETARY <br /> <br />Saturation Plats. Studies. In. order to. determine accurately the. <br />wilter holding. capacity of the soils and to note the rate of water. <br />absorption, small plats of land were saturated at a number of points. <br />Duplicate plats were established at Hastings College, Ingleside Nor- <br />man, Holdrege and at the Swedish Mission northwest of Holdrege, <br />and single plats at Bertrand and Kenesaw..These points are satisfac. . <br />tonly representative of the soils of the area. <br /> <br />The plats. were c~m~tructed by building a dike. around them with. <br />soil taken from the .outside of the plat. In each caseapproiimately <br />15 inches of water was added. Where plats were in duplicate one of <br />them was covered. with a mulch usually of straw, .in. order to check <br />rapid surface evaporation. It was thought that the mulched plat <br />would more nearly represent the actual. condition from fall irrigation <br />since;in the faU and winter.the rate of evaporation is relatively low. <br />Composite samples were taken in the immediate vicinity <if the plats <br />in order to determine the amount of water already in the .soil at the <br />beginning of the test. <br /> <br />Rate of Water Absorption. The rate at which a soil will absorb <br />water is of practical importance under irrigation. It has. a direct <br />bearing on the possibility of spreading water over the land. All soils <br />of this project were found to. take water at a rate entirely satisfactory <br />for irrigation purposes. The time. required for the soil to take in 5 <br />inches of water varied from approximately 40 minutes to a little .more <br />than 80 minutes, depending largely on the soil type and the initial <br />dryness. <br /> <br />Field Carrying Capacity.. The field carrying. capacity of a soil fs <br />that. water which it will hold after excess gravitational. water has <br />percolated away and th~ water content has come into equilibrium with <br />the capillary forces of the soil. If more water is added above the <br />amount that will be held by capillary forces, it is free, and WiIl move <br />doWnward by gravity.. This condition was obtained by flooding the <br />suil. and by mUlching to prevent rapid surface evaporationuntiI <br />equilibrium had been obtained. <br /> <br />It was planned when the saturation plats were established to <br />sample at the end of 2, 5, .10 and 30 days; - however,' so much rain <br />occurred during the spring and early summer that it was impossible <br />to follow this plan and rather irregular samplings were obtained.. <br />Plats from which the field carrying capacity data were obtained were <br />flooded April 18 and 19 and the sampling on June 25 taken as repre- <br />sentative of the field carrying capacity of the soil. At that time none <br />of the plats had received more thim one inch of rain for a period of <br />ten days, the heaviest being a .rain of .82 of an inch on June 22nd .at <br />Hastings. In the third and fourth columns of Table 9 is shown the <br />total field carrying capacity of. the soil in both percentages and <br />inches of water. <br /> <br />"'oJ <br />."