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<br />-. <br /> <br />lG.1 i <br /> <br />(Projecrliilids) <br /> <br />~ore definite conclusions can be ~de from n detailed survey in whioh <br />not only the depth and texture of the soil would beoome known to <br />greater depths, but 0.1.0 the amount of permeability or rate of soil <br />moisture movement would be studied. <br /> <br />It was realized at tho start of the land classification studies <br />conducted in the area that because much of the soil is derived fran <br />shale. the drainago faotor was of speoial importnnce in the finnl <br />determination of the vnrious lnnd olasses; consequently, only those <br />arens believed to hc.ve good natural drainage and arens which could be <br />artificinlly drninud ct n lmv cost, providing it became necessnry, Were <br />olass~d es irrignble. <br /> <br />Supplementnl wator <br />need for more extensive <br />cnsos _satisfno,t_~ry:.-=--_:: _ <br /> <br />for the Illnd presently irrigo.ted mny crente the <br />drainnge systems which at present are in most <br /> <br />--- --- <br />-------- <br />- - - - <br /> <br />. ____ _ d_____ _ ___ <br />- - -------- <br /> <br />--------- <br />.._-~--- --- <br /> <br />~--- .-- <br />" <br />-- --...- <br /> <br />'~:-:-':_~si:u~r~=c:!~~i~~ty-~:--:- :c.~___ __:"-~o::- ~--~ <br /> <br />. <br /> <br />In numorous spots tho sheles undcrlying parts of thc nron on the <br />Eastorn Slope and outcropping on the hill slopes ara houvily imprcg- <br />nated with soluble SnIts. These consist lcrgely of sodium sulfato. <br />cnlcium sulfnte. mngnesiUlll sul.fe.te, nnd s=llor amounts of sodium chlo- <br />ride. The soluble snIts are dissolvod by tho surface wator which flows <br />into tho Arknnsas Rivcr nnd its tri buU,ries c.nd by drc.inago wnter whic h <br />percolctes through the subsoil nnd sha.ly substr~tum. Rivor wator ~s it <br />comes from the meunt~ins is nearly pure, but nfter entering tho rug ions <br />whoro soepnge occurs it becomos contaminntod with salts. Tho ooncon- <br />tration inoroC\so s downstroc.m. <br /> <br />In addition to nlknli salts somo cf tho shale beds contribute se- <br />lenium to the soil which rosults in livestook lassos whon nnimAls oon- <br />sumo cortain native plc,nts or rnnge weods. Howovor, these plnnts dis- <br />appear undor irrigation fnrming ns demonstrated by tho fe.ct thc.t little <br />or no livestock poisoning has ocourred on tho prosently irrigatod'lund, <br /> <br />Alkali in sufficient nnounts to be seriously toxic ocours only in <br />canparntivoly smnll arons. The degroe of nlknlinity c.nd t\IIlount of sol_ <br />uble salts prosont in the'soil are closoly nssociated with the amount <br />of leaChing and drninc.go tlr.t occurs with irrigation. The presenco of <br />"blc.ck c.lkali" which is associc.ted with a high pH was not observed in <br />tho presently irrigatod croas. This is probe.bly tho rosult of npply- <br />ing irrigation water oontnining lc.rgo q~ntities of oalcium sulfnte' <br />which ~h(".ng~H. +'ho j.nsol~bl~ ~odi1D'n &f.J.l+.s; ....Q f\. sc.lup] f? f'Jnn. '!lhir.h i.n <br />----e--~-----~ <br /> <br />10 <br />