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, DEPARTMENT Of. PUBL.IC, WORKS TABLE NO. 9. (,~~nc]D~~d)~FI,:I.d C.Rl'r}'ln.,g C.a~a~~t!. ~.n. .~nch~~, of ~~t~r In the ~[ulched. Sa~~rat1on .p"tts.. . Weight Hygro- . Field Carrying ,. . Availl1ble Water Depth per scopic Capac~.ty Capaci ty Foot cu. ft. Coefficient Percent "Inches Percent Irtches Bertrand 1 . 79.3 1L,9 29,0 4042. .. .1.7.1 .2.61 2 86.7 12.5 2404 . 4,07_ 11.9 .1,98 .3 91,8 12.0 21,2 3.74. 9.2 1,62. 4 90,8 1004 21,2 3.io ," ,. iO.8 1.89 50. 80.6 9.8 . 20.9 '. 3.4i. ... . H,l. 1.85 6 84.6 9.7 21,0 3.42 11,3 1,84 Ave 86,6 11,0 23,0 3.81 11.9 1.97 I efficients of each foot section to six feet of the soils from various points. Available Water Capacity. The available water of a soil is that portion of the .moisture content which can be utilized for plant growth. The available water capacity is obtained by substracting the hygro- scopic or nonavailable water from the field carrying capacity. . The amount of available water a soil will hold is the important. fa:ctor from a cropping standpoint. The amounts of ~vaihible water that various 30ils of this project will hold in each foot section, together. with the averages, are shown in. the last two columns of Table 9. The available water is shown in both percentages. and inches of 'water. Moisture Eqrrivalent. The labor involved in establishing saturation plats and the difficulty of getting sufficient water for saturation lin:lited the number of such studies. It was desirable, therefor, to use some laboratory method for making studies of the field. carrying. capacities of soils in other regions than those where the. saturation plats were located. For this purpose the moisture equivalent' of the soils was used. Table 10 shows the relation by foot sections between the moisture equivalent of a soil and the field carrying capacity, as. determined from samples taken from. the m~lehed saturation plats. This relation- ,ship is shown for each foot section of soil. It will be noted that tl,1e moisture equivalent is always less than the field carrying capacity for the surface foot, but more than the field carrying capacity for ~he ~ections of soil below the first foot. .The average field carrying capaci,ty for the upper six feet of soil was found to be 91. per cent of the average moisture equivalent of the same samples. While this might not hold for an individual foot section of soil, it does hold within practical limits when the upper six feet are considered. In order to. get data on the moisture holding capacity in various parts of the area, samples were taken on representative soil types thruout the whole project. (See Map 1) Moisture equivalent and hygroscopic coefficient were determined on each foot section of .these I J I I' l j.." . ~2V . .