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1637 (Projoct lands) -. depth ranging fr~ 10 to 18 inches. The subseil of the no.ture soil extends to dopths of fram 5 feot to as T.luch as 20 feot or nore. Tho onturo soils hnve developed principally on gentle slopes or nearly level areas where orosion has been ~nor. The line ef demo.rcation be- tween the topsoil and the subsoil is r.loro distinct in the heavy soils where moisture movement is moo h slower than in light soil. A gravol substratum is seldam found in mo.ture soil profilos, consequently natural drainage is restrieted. Irunuture seils oceur for tho most po.rt on the slopes where tho top- soil has been removed by wind or wo.tor erosion alnost as repidly as it was f0~ed. Sone of tho imno.turo soils consist of duno sand, silty loess material, o.nd alluvio.l outwo.sh. Tho ia~aturo soils deriv~d frao largo stream dcposits usuo.lly h~vo 0. gro.vel substro.tum whioh provides oxcollent natural subdrainago. whoreas tho so soils dorived frcn smnll streo.n or wind doposits ho.ve no gravol substro.tun. . Soil toxturo vO-rios fr(,n shnllow gro.velly soil to very heavy clo.y or adobe soil, end is dependont upon the parent matorial from whieh the soil is derived. The soils of the aroa hnve beon derivod froM. do.rk, elive-brown clay shele (Pierro shale); yoll~v, groy, or yollowish-brown, highly gypsiforous she.lo (Apisho.po. sho.lG~ Carlilo shale, c~d Graneros shale); li;:;ht grey Ghr-ly li.':1.Cstono (Ti..~pr.s linestone); sandstono (Dnlw- ta sandstene); sandy stream or wind deposits; and old o.lluvial doposits on river bonehes or torraces. It is ostimo.ted that about two-thirds of the area whioh hns been survoyed consists of silty loan, clay loo.n, and clay soils and tho reIlUlindor consists of fino so.lOdy lel)JJl er sundy soils. Exhibit 2 shaws the goelogico.l formo.tions of tho area. In nearly 0.11 soils of tho area there is an abundance of lime which is particulo.rly valur.ble in mo.into.ining go,od s)il structure and in mo.k- ing drainago and reclamo.tion from alkali easior o.nd more effective. On tho prosontly irrigatod lands it was originally beliovod that, duo to the newnoss and =tural fortility of tho soils of this rogion. fortilizors were not noeded. i;Janure was not so.vod, straw o.nd stubblo fields Were burned ovor. and tho uso of com."l6reial fertiliz ors WaS ridiculed. During moro rocent yeo.rs, h~'ev8r, it has been found that manuros, woll-rotted straw, corn stalks und groen mo.nuro creps plowed undor, and in "any eases tho Uso of comDllJroial fortilizers rich in phosphnte prove beneficial. In this respoct, tho neW knowlod:;e regard- ing tho need for and mnnner of consorving and maintaining soil fertiI. i ty on the new lands to ])0 initially irrigatod, will be particularly advantageous. Although tho nitrobon content of tho soils is good and oo.sily rno.in~ined by the usa of logumo crops, tho organic muttor eon- tent is low. This condition is cheracteristic of most semi-arid soils which have even 0.' low dogroo of alkalinity. --. 6