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4 > Image 4 of Kentucky farm and home science, vol. 3 No. 1 winter 1957

Part of Kentucky Agricultural Experiment Station

Another tool in making better fertilizer and management we recommendations used when '_ I O` O u ' X-Rays Identify Soil Minerals 1 P th By T. B. HUTCHESON, ]R. ll ]ust as X-ray methods are used by medical men elements against leaching, but not against absorption p to detect early symptoms of human diseases in time by plant roots. _, for simple cure, X-ray studies of our soils may reveal The kaolrin group of clay minerals presents the T properties that could lead to starvation and sickness smallest surface area, and its individual units are si} of our crops, unless proper soil treatment is carried composed of one layer of silicon and oxygen atoms _ out. Such an analogy is somewhat unfair, however, bound to another layer of aluminum, oxygen and ;,, since the X-ray studies of soils do not actually detect hydrogen atoms. tif "sick" soils. It would be more correct to say that The clay mineral group presenting the greatest J, Xray studies aid in Ending out just what minerals surface area for reactions is the montmorillonite group V are present in our soils, and with this knowledge whose members are made up of units composed of ( A better fertilizer and management practices may be one aluminum-oxygen-hydrogen layei sandwiched be- recommended. tween two silicon-oxygen layers. Units of this kind " . lt has been known for a number of years that most are ordinarily not bound tightly to each other and gill minerals, even those that make up the fine clay may readily expand or CO1lt1'HCtSOlT1BtllllS trapping _ fraction of the soil, are crystalline. The elements elements such as potassium that are needed by plants. M that make up crystalline minerals are arranged in A third group of clay minerals, the hydirous micas, ` an orderly manner which is characteristic of the is intermediate in surface area and reactability be- . particular mineral. This property makes possible the tween the two groups already mentioned. Units in , identification of clay minerals by X-ray measurements. that group are similar to those of the montmorillonite group except that slight differences in the composition X'Y Bm P**F Rdd of the layers are compensated for by the presence X-ray examination is made by placing the mineral of potassium ions between the units. The attraction { iuaterial in the path of an X-ray beam and then of the units for the potassium ion is quite strong, and wl recording the pattern of the beam after it has en- this prevents much expansion from taking place. The Q , . countered the material. The crystal structures of the hydrous inicas apparently release small amounts of Ll iiiiiierals cause the X-rays to be bent or diffracted in the interlayer potassium to plant roots under certain ( different patterns that are just as characteristic of conditions. l individualr`minerals as fingerprints are of individual Many Differences Among the Groups na persons. Ihe patterns obtained are then compared _ , with those of "known" minerals for identification. Today llllmy fllllelfgllces are klmwll to exist among U" The various crystal foruis of minerals are asso- tllcso Clay mllwml groups that MQ at *lQl`lCl*ltUl`l eiated with physical and clieinical properties that are llllplllftllllco uml umlOlll)t(lly> Ollwl llllljlilfllclis will 4 M impm_tmm_ in pmctiml ugl_icUltm_l_ TM wry tiny be discovered in the future as the tools of research 1 _ Clay mhwmls uw must impolhlnt in tllis l_(_gm_d bw become Ill()1` ref111ed. The identihcation of these g cause of the tremendous amount of surface that they lllllllimls uml fl lmowlcflge at llwll lmll`flS uw _ Pl.l_S(_Ht umm which I.(_uCti()m may mh, plump UW seutial to a wellrounded agricultural program, `* believeable as it seems. a pound of clay possesses from lll ll Pmvlolls lsslle at Kclllllclfy Fall" (md lI"") if about 5 to 90 acres of surface area when all of the Sclmlccl D1" H` lil' Bailey (lesclfllwfl S(` "*`k l`l" small plates and edges are considered. Priiicipal re- iii_ it Bujl4_y S.,ii g;i,,m,,U(,,, pmgm,,,_~ K)., ML ( actions of interest in CI'Ol) production are the water- ENDL SPL K> Filflll Mild H<>m Sci-. 2 (1): 3. 1956. ek holding capacity and the retention of plant nutrient (50,,,;,,,,ed 0,, page 12) g ` 4 Ki:N1ucxY FARBI AND Hoxn; ScinxcE\VixTnn 1957 \ .1*