THE UNIVERSITY OF ILLINOIS LIBRARY 630.7 I16b co p A6RICULTURAL UIBW UNIVERSITY OF ILLINOIS Agricultural Experiment Station BULLETIN No. 232 I: POTASH SHALES OF ILLINOIS II: GEOLOGY, DISTRIBUTION, AND OCCUR- RENCE IN UNION COUNTY III: FINELY-GROUND SHALE AS A SOURCE OF POTASSIUM FOR SOIL IMPROVEMENT A joint publication by the Division of Applied Chemistry of the University of Illi- nois; the Illinois Geological Survey; and the Agricultural Experiment Station URBANA, ILLINOIS, MARCH, 1921 CONTENTS OF BULLETIN No. 232 PART I: POTASH SHALES OF ILLINOIS PAGE Introduction 229 Constitution of Illinois Potash Shales 231 Extraction and Concentration of the Potash 235 Conclusions . 235 PART II: GEOLOGY, DISTRIBUTION, AND OCCURRENCE OF THE POTASH-BEARING SHALE OF UNION COUNTY Introduction 237 Topography 237 Character of the Shale and Associated Rocks 238 Availability 241 Localities of Possible Commercial Importance 241 Localities Mainly of Local Importance 243 PART III: FINELY-GROUND SHALE AS A SOURCE OF POTASSIUM FOR SOIL IMPROVEMENT . . 244 FOREWORD Some five years ago Professor S. W. Parr, of the Division of Applied Chemistry at the University of Illinois, began a 'somewhat exhaustive study of Illinois shales as a source of oil, samples being furnished by the State Geological Survey, and as in all such cases gave careful attention to possible by-products. Most of the shales examined proved poor in oil-bearing properties, but some of them were surprisingly rich in potassium compounds. Dr. Robert Stewart, of the Agronomy Department, in common with other students of soil fertility, was at the same time interested in every possible source of potassium available for agricultural purposes. Upon being advised by Professor Parr of the promising character of Illinois shales, he began at once experiments intended to show whether the par- ticular potassium compounds present in these shales could be made available for agricultural purposes. The present publication consists of three parts : Part I, prepared by Professor Parr and Mr. Austin, of the Division of Applied Chem- istry, presents a brief account of the potassium-bearing quality of these shales; Part II, prepared by Mr. Frank Krey, of the State Geological Survey, gives the location and approximate extent of the deposits; and Part III, prepared by Dr. Stewart, reports the pre- liminary investigations into the agricultural side of the problem. While further experimentation will be necessary to determine whether these potassium compounds can be made available under field conditions, enough has been done, not only to show the presence of vast amounts of this valuable material in Illinois shales, but also to demonstrate that the compounds are capable of reduction by agri- cultural plants grown under laboratory conditions. E. DAVENPORT FIG. 1. EFFECT OF SHALE ON THE PRODUCTION OF CORN The pots were filled with peaty soil to which was added the materials indicated. The yield of corn fodder on the shale pots was twice that on the check pots. See page 251 for further particulars concerning this experiment. PART I POTASH SHALES OF ILLINOIS BY S. W. PARE, PROFESSOR OP APPLIED CHEMISTRY, AND M. M. AUSTIN, ASSISTANT IN CHEMISTRY During the years 1916 and 1917 certain Illinois shales were being studied in the laboratory of applied chemistry at the University of Illinois, with primary reference to the amount of oil they would produce upon destructive distillation. The shale from only one region, Johnson county, proved to be sufficiently rich in oil (45 to 50 gallons per ton of shale) to be of interest for its oil yield alone. Numerous other shales were found giving from 15 to 20 gallons per ton, and hence of questionable value from a consideration of their oil possibilities alone. This constituted, therefore, a primary reason for examining all samples for other values, such as phosphorus and potash. The samples were furnished thru the courtesy of the Illinois State Geological Survey and came mainly from the southern part of the state. Phosphorus, except in insignificant amounts, was not found in any of the shales. Certain samples, how- ever, gave a percentage of potash quite unexpected and quite unusual for material of this type. It is fairly well conceded by students of the potash situation in this country, at least from the chemical viewpoint, that the most hope- ful source for a domestic supply resides chiefly as a by-product from the manufacture of cement. The shale or other siliceous material that enters into the raw mix for cement-making always carries a certain percentage of potash. In the process of burning the clinker, this potash assumes the volatile form ; hence it may be recovered by simple methods of condensation and leaching. Even tho the average shale as used in the cement mix does not contain, on the average, more than from 1.5 to 2.5 percent of potash (K 2 0), still the potential supply from this source, in the aggregate, would be very great. The Illinois shales that we are here considering, instead of having an average potash content of 2 or even 21/2 percent, have a content of 5 percent, in the raw state. They compare, therefore, very favorably with the green sands of New Jersey, concerning which not a little consideration is now being given both in the literature and financially, as a possible source of supply for this important product. 1 The first 1 Chem. and Met. Eng., 22, 815. 1920. 229 230 BULLETIN No. 232 [March, question that naturally arises, therefore, relates to the suitability of" these Illinois shales with reference to their main constituents for the purpose of compounding into a suitable cement -mix. The best authority on this phase of the topic is Professor A. V. Bleininger, who in his study of Illinois shales for cement-making, 1 gives analyses for eight samples which he deems suitable for such a purpose. They show so little variation in composition that for purposes of illustration in this discussion they may be fairly represented by an average value for each constituent. These values are given in the second column of Table 1. For comparison, therefore, as to their suitability along cement lines, two of the high-potash shales are shown in parallel columns 3 and 4. TABLE 1. COMPARISON OF ILLINOIS SHALE CONSTITUENTS WITH REFERENCE TO THEIR CEMENT-MAKING PROPERTIES Average of eight Illinois shales (Bleininger) Sample No. 1 Illinois potash shales Sample No. 2 Illinois potash shales SiO, . 61 56 53.8 55.0 Al.O, . 16 12 17 7 163 Fe,O, . 296 58 1 60 1 Fe O 3 52 CaO 094 7 0.3 MgO .. 1 79 1.8 1.5 K 2 O 2.90 5.0 4.9 Na 2 O 0.82 0.5 0.4 Ignition loss 6.72 11.9 13.0 1 Total iron calculated to Fe 2 O,. Probably the most characteristic feature of this table from the cement-making standpoint is the ratio between the silica (Si0 2 ) and the alumina (A1 2 3 ). According to the average American practice, this ratio should fall between 2.5 and 3.5. Upon calculating these ratios for shale samples Nos. 1 and 2 of the table, we have : Shale No. 1 Shale No. 2 53.8 17.7 55.0 = 3.02 = 3.37 Hence, it is evident that on the basis of the silica-alumina ratio the two samples of the potash shales under consideration are seen to be in the most advantageous zone. Since, in the process of compounding to produce a suitable cement clinker, a shale is mixed with from two to three times its weight of limestone, it follows that the percentage of K 2 in the raw mix is correspondingly reduced. In the average American practice this fac- tor amounts to from 0.7 to 1.0 percent, and on this basis with a 66% '111. State Geol. Survey Bui. 17, p. 101. 1912. 19i!l] PART I: POTASH SHALES OF ILLINOIS 231 percent recovery of the total potash there would result an average yield of about 2.9 pounds of K 2 per barrel of cement made. On the same basis the potash shales as given in columns 3 and 4 of Table 1 should show a yield of 5.4 pounds per barrel. On this basis, estimating the price of potash at 15 cents per pound, the shales here studied would return a value for the potash recovery alone of 82 cents per barrel of cement made, as against 19% cents recovery from the average potash content of the ordinary raw cement mix. Reference thus far has been made only to the shale values from Union county in southern Illinois. But one other region in the state has thus far supplied a shale with a high potash content. This has come from the neighborhood of Dixon, in Lee county. This shale shows a potash content in the raw state of 5.8 percent. It is coarse- grained, friable, and while of a green color suggestive of the eastern green sand, the geological character of the material is quite different. CONSTITUTION OF ILLINOIS POTASH SHALES The shales from Union county are peculiar in that they have a small percentage of oil which is present in the free state. This has no industrial significance, but being volatile it adds to the other volatile constituents, such as water of hydration, so that upon ignition the reduction in weight, as shown in Table 1, amounts "to about 12y 2 percent of the raw material ; hence upon ignition the potash content of the residue is seen to be 5.75 percent. With the Dixon shale but little loss on ignition occurs (see Table 3) ; hence the potash percentage remains about the same in either the ignited or the raw state. For determining the form of combination in which the potash is held, no very simple or direct method is available. One procedure con- sists in digesting one gram of the sample with 25 cc. of concentrated sulfuric acid, heating the same until about half of the acid has been removed, diluting, filtering, washing, and igniting the residue, and analyzing it for total potash. The percentage of potash lost is con- sidered as being in some other than the feldspathic form. By this procedure 62 percent of the total potash was found to be removed from the Union county shales, while from the Dixon shale only about 15 percent was removed. This shows a marked difference in the chemical composition of the two shales. Further proof of this difference was desired. It is true that in the process of cement manu- facture the potash would be equally recoverable in either case ; never- theless, from any other standpoint, differences in the ease with which the potash might be removed by chemical solvents or concentrated into a form for more ready extraction, might make a wide difference in the value of the' shales from the two sources. It is not the purpose of this discussion to go into the details of the experiments to determine the chemical character of the potash-bearing 232 BULLETIN No. 232 [March, constituents. The method of analysis just described suggests that the potash in the Dixon shale is chiefly or altogether feldspathic in com- bination, and that the major part, at least of the potash in the Union county shale, is in some combination more nearly resembling the glauconitic or green-sand formations. These formations are considered as being potassium iron silicates with an average potash content vary- ing from 5 to 7 percent K 2 0. With the marked difference in type suggested by the analytical results obtained from the use of concentrated sulfuric acid, it seemed worth while to prepare thin sections for study under the microscope. No very positive information came from such studies. In general it seemed evident that the Union county shales had passed thru extensive secondary decompositions and that the Dixon shales had not. Both types however, even in the undisturbed condition of the deposits, had their ultimate particles in such a finely divided state as to render impossible their resolution and study under the microscope. A third method of study into the probable type of composition suggested itself as follows: Accepting the generally conceded fact that potash in feldspathic combination is but very little, if at all, directly available as plant food, it might afford further data on composition if experiments were inaugurated to determine whether the Union county shales contained some of their potash in a form which was directly available for plant use. Some foundation for this theory was already afforded by the fact that 62 percent of the total potash in those shales, as already determined by analysis, was soluble in acid; thus furnishing a start- ing point in the evidence as to their difference from feldspathic material. Moreover, if the Union county shales responded to plant requirements and the Dixon shales did not, the evidence would pro- ceed one step further. And again, if the Union county shales were treated with strong acid in such a manner as to remove all their acid- soluble potash, and if, after being freed from acid, the residue with the remaining 38 percent of potash (presumably in feldspathic combina- tion) was submitted to plant action and was found lacking in avail- able potash, this would afford a still further proof in the chain of evi- dence as to the type of potash combination in the original shale. Fortunately at this stage of the chemical studies, upon appealing to the Agronomy Department of the College of Agriculture for help in conducting the necessary pot cultures, it was found that such a procedure fitted in well with a program of their own concerning studies on the availability of potash as plant food, in a series of natural substances; hence the potash shales in hand would furnish an addi- tional type of material. It is not the purpose in this part of the discussion to go into the details of the results from these pot cultures further than to correlate 1921] PART I: POTASH SHALES OF ILLINOIS 233 the results in so far as they have a bearing upon the shale composition as already set forth. In Table 2, therefore, an attempt is made to show the behavior of the various shale materials applied to a peat soil deficient in potash. Buckwheat was selected as the plant most responsive to the varying treatments. An equivalent quantity of potash was added in each case, except of course, to the check pot, which being used for compari- son was without addition of potash in any form. Each pot was made up of 7 kilos of peat soil, 60 grams of pulverized limestone, and the various types of shale material ground to pass a 100-mesh sieve and in an amount that would carry into the soil mixture in each case a total potash content of 1.34 grams. TABLE No. 2. COMPARATIVE STUDY OF PLANT GROWTH (BUCKWHEAT) USING SHALE MATERIALS OF DIFFERENT COMPOSITION DESCRIPTION OF POTS CONDITION OF PLANTS Six WEEKS AFTER PLANTING No. 1 Check pot using peat soil with in- sufficient potash Poor growth No. 2 Peat soil as in No. 1, with Dixon shale Poor growth, not distinguished from No. 1 No. 3 Peat soil as in No. 1, with Union county shale, less 62 percent of potash by acid extraction Poor growth, not different from Nos. 1 and 2 No. 4 Peat soil as in No. 1, with Union county shale ignited Excellent growth more dense and taller than Nos. 1, 2, or 3 No. 5 Peat soil as in No. 1, with Union county shale, sample No. 1 not ignited Excellent growth, not distinguishable in density or vigor from No. 4 No. 6 Peat soil as in No. 1, with Union county shale, sample No. 2 not ignited Excellent growth, equal in every re- spect to Nos. 4 and 5 This amount of potash represents the weight per acre that would be present in a normal soil which was deemed to have an adequate supply of that constituent. The results as presented in the table are also very clearly shown in the photographic reproduction. Pot No. 1 is the check, with deficient potash. No. 2 has the standard equivalent of 1.34 grams of K 2 added in the form present in the Dixon shale, and No. 3 has the same addition in the form of acid-insoluble residue from the Union county shale. An exam- 234 BULLETIN No. 232 [March, ination of these three pots seems to warrant the conclusion that potash in any available form is lacking in each case. This, therefore, would seem to confirm the previous assumption that the potash present in Pots 2 and 3 is in the f eldspathic form. FIG. 2. BUCKWHEAT PLANTS GROWING ON PEAT SOIL TO WHICH VARIOUS SHALE MATERIALS HAVE BEEN ADDED 1 Check 2 Dixon Shale Union Co. Acid ex- tracted Union Co. Ignited Union Co. No. 1. Not ignited 6 Union Co. No. 2. Not ignited By further reference to Pots 4, 5, and 6, there is an equally obvious indication that in these pots there is potash present in a form available for plant use; and since the only variable in the experiment is the acid-soluble constituent, it is evident that the potash utilized by the plant comes from this source. Moreover, ignition or non-ignition of the shale does not affect the property of the potash so far as food availability is concerned. It would be of scientific interest, of course, to be able to say more definitely what was the form of potash combination here found. We have compared it thus far in the discussion to the green sands of the eastern United States, which are true glauconites. The most that can be said of these shales is that they are glauconitic in type. They may have been originally a feldspathic deposition which has undergone secondary decomposition in situ. Indeed, the region has other striking examples of secondary decomposition products resulting from similar methods of decomposition; for example, the very pure deposits of 3921] PART I: POTASH SHALES OF ILLINOIS 235 amorphous silica, found so abundantly in Union county. So far as conformity to green-sand or glauconitic conditions is concerned, there is every justification for such a classification, as may be seen from the following quotation, 1 indicating the geological conditions under which the true glauconites are supposed to have been formed : ' ' The organic matter transforms the iron into sulfid which may be oxidized to hydrate, sulfur being at the same time liberated. This sulfur would oxidize to sulf uric acid, which would decompose clay, setting free colloidal silica, aluminum being removed in solution. Thus, we have colloidal silica and hydrated iron in a state most suitable for their combination. The potash which is necessary to complete the composition of glauconite may be derived from the decomposed fragments of crystaline rocks like orthoclase or white mica." Upon analysis of the shale for iron in the pyritic form by methods developed in this laboratory, 2 it appears that when the pyritic iron is deducted from the total iron of the shale there remains 3.8 percent of iron available for combination with the 3.1 percent of potash pres- ent in the acid-soluble form, an amount which approaches the ratio for glauconitic material with sufficient approximation to warrant the classification thus proposed ; viz., not true glauconite but glauconitic in type. EXTRACTION AND CONCENTRATION OF THE POTASH It is perhaps sufficiently evident from the preceding description of the composition of all these shales that no practical method for the extraction of the potash on an industrial basis is possible. This con- dition, however, does not preclude the method of extraction by way of the cement-making process. In any case where the by-products have values, such a combination process may come within the range of industrial possibility. It is not considered essential to this dis- cussion to give the details of the experiments directed toward extrac- tion or solution methods for direct recovery of the potash. While practicable as a laboratory procedure, they would not be profitable as industrial processes. CONCLUSIONS 1. Shales occur in at least two localities in Illinois, which contain 5 percent or more of potash. 2. Shale outcropping in several places near Jonesboro, in Union county, which contains 5 percent of potash would be suitable, so far as can be determined from its chemical composition and physical character, for use in the manufacture of Portland cement. 'Clarke, W. B., Jour, of Geol., 13, p. 509. 1900. ^Powell, A. B., with Parr, S. W., Univ. 111. Eng. Exp. Sta. Bui. No. 111. 1919 236 BULLETIN No. 232 [March, 3. By using this material in the manufacture of cement and by applying the known methods of potash recovery, a yield of 5.3 pounds of potash, repre- senting a value of 70 to 80 cents per barrel of cement, could be obtained. 4. The constitution of the southern Illinois shale is complex. The shale contains free oil, bituminous matter, pyrite, undecomposed potassium-bearing rock, feldspathic in character, and potassium-bearing material of the nature of glau- conite or green sand. 5. Shale from Dixon, Lee county, contains 5.8 percent of potash, which is held for the most part in a more stable condition than that in the southern Illinois shale. 6. Extraction of the potassium from shale of either the southern Illinois or the Dixon type by means of solid or liquid reagents would seem to be im- practicable, because of the cost of leaching and recovering potash from material where it is present in such small amounts. 7. The plant availability of the potash in the southern Illinois shale is probably characteristic of all the material of this type outcropping in that locality. 8. That part of the potassium in the southern Illinois shale which is soluble in sulfuric acid, is shown to be in a combination of the glaueonite type. 9. In southern Illinois shale having a potash content of 5.0 percent in the raw condition or 5.6 percent when ignited, 62 percent of the total potash is glauconitic in character and is available as plant food. TABLE 3. ANALYSIS OF ILLINOIS SHALES* Location Sample No. Ash Si0 3 A1 2 O 3 Fe 2 O 3 CaO MgO K 2 Na 2 O Green shale above black shale at - 1 96.9 2.9 Caney creek . . . 2 97.7 3.5 3 86.2 5.2 4 88.0 5.7 Black shale at Caney creek .... < 6 7 10 88.1 87.1 87.3 61.0 63.3 61.5 20.2 18.7 18.7 6.6 6.9 6.5 0.8 0.4 0.9 2.0 1.7 1.8 5.65 5.58 5.7 0.6 0.5 0.6 11 85.5 66.0 17.8 6.5 0.2 1.3 5.0 0.7 12 86.0 5.4 Black shale at State Pond 8 89.1 5.5 Black Shale at Moun- tain Glen 9 86 1 5 6 Green feldspathic shale at Dixon. . . 5 97.3 5.8 *The factors for SiO 2 , A1 2 O 3 , etc., are referred to the shale ash as 100 percent. 1921] PART II: GEOLOGY OF POTASH SHALE OF UNION COUNTY 237 PART II GEOLOGY, DISTRIBUTION, AND OCCURRENCE OF THE POTASH-BEARING SHALE OF UNION COUNTY BY FRANK KEEY, STATE GEOLOGICAL SURVEY The black potash-bearing shale of Union county comes to the sur- face in a belt 75 to 200 feet wide along the west slope of the ridge that lies about one mile west of Jonesboro, trends a little west of north, and ends IVk miles south of Alto Pass, at Clear creek, in the Southwest 1/4 of Section 22, Township 11 South, Range 2 West. At its north end, the shale is terminated by a northwest-southeast fault which brings rock of the Chester age into contact with Devonian strata. The southernmost exposure of the shale is seen in a narrow ravine in the south-central part of Section 23, about half a mile north of the Ham- burg road. South of the Hamburg road no black shale occurs, and while both the overlying and underlying rocks may be seen in numer- ous exposures, either the black shale was never deposited here or else it was removed by erosion prior to the deposition of the overlying green shale. The southern limit of the black shale is therefore within half a mile north of the Hamburg road. The exact limit can readily be determined by exploration. TOPOGRAPHY The ridge on whose western slope the black shale outcrops, is not continuous but is interrupted at intervals by gaps formed where creeks have cut their way thru the hills. Such gaps vary in width from less than a quarter of a mile to more than half a mile. The crest of the ridge is from 150 to 225 feet above the level of the creek flats, and the horizon of the black shale is 40 to 100 feet below the crest of the ridge except at the gaps where the easterly dip of the rock brings it to the level of the flat, usually within a distance of an eighth to a quarter of a mile east of the crest. In general, the eastern slope of the ridge is gentle, 8 feet in 100 being a fair average. The western slope is more abrupt, especially the upper 100 feet. Here vertical, or nearly vertical, faces for short dis- tances are not uncommon, and slopes of 15 to 20 feet or more in 100 prevail. The lower slopes, however, are not very different from those on the east flank. Numerous small lateral ravines which divide and redivide as they approach the crest add greatly to the rough and broken character of both the east and the west slopes. 238 BULLETIN No. 232 [March, CHARACTER OF THE SHALE AND ASSOCIATED ROCKS As the black shale disintegrates rapidly on exposure to the weather, good outcrops are met with in only a few particularly favor- able localities. However, some of the more resistant associated strata are more frequently met with, and therefore their outcrops may serve to determine the location of the shale in places where it is not exposed. For this reason, in part, a somewhat careful description of the over- lying and underlying strata is made here. Section of the Black Shale and Associated Strata Feet 1. Loess, gravel, and iron conglomerate (Cretaceous or later) 0-40 2. Cherty rock (base of Burlington) 2-30 3. Green shale (Springville shale) 30-60 4. Black potash-bearing shale (Mountain Glen shale) 35-45 5. Brown, fine-grained siliceous and cherty limestone . . . . > Alto 20 - 25 6. Brown, thin-bedded siliceous shale ) formation 30 The loess is a fine, brown to chocolate-colored siliceous material, probably wind blown. The gravel consists of well-rounded chert pebbles which range in size from a pea to two inches in diameter, but average less than one inch. Fragments of iron conglomerate (chert pebbles cemented together by iron oxid) are often found on the slopes. No good exposure showing the relations and separate thicknesses of the loess, gravel, or conglomerate was seen, but field observations suggest that the conglomerate lies just above the cherty rock; that the gravel overlies the conglomerate ; and that the gravel is in turn overlain by the loess. The loess, gravel, and iron conglomerate together make up the gently rounded tops of the ridges. The cherty rock, thought to be the base of the Burlington lime- stone, varies somewhat at different localities. In the northern part of the area it is made up of massive beds, 2 to 8 feet in thickness, which on their weathered surfaces strongly resemble a quartzite or well- cemented, fine-grained sandstone, but where fresh appear to be re- crystallized chert. Four-inch bands of true chert or flint are often found along the bedding planes. Farther south the rock consists of chert layers alternating with fine-grained brown limestone. It is very probable that the ridge owes its origin to the resistant character of this cherty rock. The green shale, named Springville shale by Savage, 1 varies in character from north to south. In the northern portion of its outcrop it is probably a soft, laminated clay shale, but no good exposures are seen. ' Toward the south, however, the shale becomes progressively more siliceous and resistant, so that it forms bluffs 10 to 30 feet high. J Savage, T. E. The Devonian Formations of Illinois. Amer. Jour. Sci., Fourth Series, Vol. XLIX, No. 291, pp. 169-182. 1920. 1921] PART II: GEOLOGY OF POTASH SHALE OP UNION COUNTY 239 Where fresh, the shale is greenish gray, hard, and siliceous; some layers are harder than others and approach a chert in appearance. When weathered, the shale breaks up into irregularly shaped chips seldom more than 3 inches long or less than % inch thick. Such chips have a mottled appearance; green, gray, brown, and red being the prevailing colors. At the base of the green-shale formation, over most of the area, is a 3-foot bed of compact, impure limestone, blue-gray where fresh, but weathering to gray-brown. It is characterized by an abundance of small siliceous geodes, seldom more than one inch in diameter. The black potash-bearing shale beneath the green (Springville) shale is thought to represent the youngest of the Devonian formations in this region, and to be the equivalent of the Chattanooga shale of Tennessee and the New Albany shale of New York. It has been named Mountain Glen shale by Savage. 1 When fresh the shale is hard, black, thinly laminated, and slaty. Pyrite is common, especially near the base. On weathered surfaces the shale splits readily into thin sheets which are lighter in color than the unweathered shale and are often stained red by iron. Beca.use it disintegrates readily under the influence of the weather, good exposures are to be found only along stream courses or on steep slopes where talus from overlying rock is constantly being removed as fast as it is formed. The fact that analyses of the Mountain Glen shale made on samples taken at the three widely separated localities indicated on the accom- panying map have essentially the same potash content, suggests uni- formity in the composition of the shale thruout its extent. For analyses see Table 3 on page 236. Below the black shale is a fine-grained, hard, brown, siliceous lime- stone. Chert is abundant both as layers and as nodules, and in some localities may make up more than 20 percent of the rock's mass. The limestone is massive in its upper portion, but becomes increasingly argillaceous with depth, until it passes into a brown siliceous shale. The shale weathers into thin- layers, % to i/4 inch thick, which com- monly break up into small rectangular blocks 1 to 2 inches long. This limestone and shale together make up the Alto formation. 1 All the above-described rocks dip about 15 in an easterly direction. The amount of dip varies somewhat at different localities, but in gen- eral it decreases to the south. Dips of 20 and more have been observed to the north, while in the southern part less than 10 is the common angle. 'Op. cit. 240 BULLETIN No. 232 R 2W , Eoad Section Township Outcrop of Mountain Line Line Glen (potash-bearing) Shale FIG. 3. MAP SHOWING THE OUTCROP OF THE MOUNTAIN GLEN SHALE AND THE LOCATIONS OF THE SAMPLES The bold-face italicized numbers are sample numbers and the arrows point to the locations where the samples were taken. 1921] PART II: GEOLOGY OF POTASH SHALE OP UNION COUNTY 241 AVAILABILITY Altho the shale is available in quantity at many places along its outcrop, there are only a few localities which have ready access to railroad transportation, and therefore have commercial possibilities. The Mobile and Ohio Railroad runs parallel to the outcrop for several miles, but on the east side, of the ridge. It is therefore effectively separated from the shale by the intervening hills except at the gaps. From the standpoint of transportation, then, the most favor- able localities for exploitation of the shale are at the gaps, specifically in the Northeast 14 of Section 34 ; along the branch of Caney creek in the Southwest 1/4 of Section 11 ; at the State pond in the south- central part of Section 14 ; and along the north slope of the ridge near the north quarter-corner of Section 23. LOCALITIES OF POSSIBLE COMMERCIAL IMPORTANCE Along Branch of Clear Creek NE. y Sec. 34, T. 11 8., R. 2 W. The branch of Clear creek here has a general east-and-west direc- tion. North of the creek is an extensive flat, but to the south the bank, which comprizes the end of the main north-and-south ridge, rises steeply from the stream to a height of about 50 feet, and then more gently to the top of the ridge. The slope is broken by numerous small north-and-south ravines leading to the creek. The black shale makes up the lower part of this slope for a distance of about 300 or 400 feet, but the eastward dip causes its outcrop to rise westward until it reaches a position about 150 feet above the creek, whence it turns south and follows the western slope of the main ridge. The black shale is overlain by about 25 feet of soft green shale which is followed by 8 to 15 feet of cherty rock ; and this in turn is overlain by a thickness of 15 to 30 feet of iron conglomerate, gravel, and loess. Along the outcrop, a strip 50 to 150 feet wide (depending on the slope of the surface), with an average thickness of about 25 to 30 feet and a length of more than 1,000 feet, aggregating more than 100,000 tons, is practically free from overburden, and could therefore be worked with relative ease. By continuing to work along the south- ward extension and by removing the overburden where its thickness is not prohibitive, the tonnage could be more than doubled. The amount of overburden that can profitably be removed is dependent on the value of the shale. Transportation is afforded by the Mobile and Ohio, which runs about half a mile east of the outcrop. The intervening ground is flat and would offer no obstacle to the building of a spur. 242 BULLETIN No. 232 [March, Along Branch of Caney Creek SW. 14 Sec. 11, T. 12 S., R. 2 W. The outcrop along the branch of Caney creek in Section 11 is very similar to that of Section 34. The creek here has a northeast-south- west direction, and the south bank has a steep slope. The black shale outcrops along the creek for 500 to 600 feet but rises to the south- west, turns southward, and disappears under a cover of loess. Farther south it reappears at places along the western slope of the main ridge. The overlying rocks are siliceous green shale about 40 feet thick, fol- lowed by a cherty limestone 20 feet and more thick, which is capped by loess. The amount of shale available with little or no overburden is lim- ited to a narrow strip probably nowhere more than 50 or 75 feet wide, and about 800 feet long. The tonnage available under these favorable circumstances would probably be less than 75,000. The great thick- ness of overburden elsewhere precludes its profitable removal except perhaps at the southward bend of the outcrop, where the loess covering might be removed and additional tonnage thereby be obtained. Transportation is afforded by the Mobile and Ohio, which runs about a quarter of a mile east of the outcrop. The intervening ground is flat and approximately at the same elevation as the. railroad. State Pond South-Central Part of Sec. '14, T. 12 8., R. 2 W. The State pond was formed by damming a small east-and-west ravine. The south bank of the pond, which is also the north slope of a narrow east-west ridge, consists of a bluff composed of green siliceous shale. Just below and west of the dam there is an outcrop of black shale. The exposure is about 100 feet long, but it rises to the west and is lost under a cover of loess ; it probably passes around the west end of the ridge, well up the slope, and swings back east on the south side of the ridge beneath the loess. The entire length of the exposure is not over 300 feet and since it is so steep as to form a nearly vertical face, the width of shale free from overburden is less than 50 feet. The overburden consists of the green siliceous shale and loess. The amount of shale that can be obtained free from overburden is small, probably less than 25,000 tons. However, should exploration show the shale to be present on the south slope and the loess over- burden to be subject to. profitable removal, a considerable additional tonnage could be obtained. Railroad transportation could be furnished by the Mobile and Ohio Railroad, which runs about an eighth of a mile west of the outcrop. 1921] PART II: GEOLOGY OF POTASH SHALE OF UNION COUNTY 243 North Part of Sec. 23, T. 12 8., R. 2 W. The black shale outcrops as a narrow band along the east-west slope, south of the Mobile and Ohio tracks in the neighborhood of the north quarter-corner of Section 23. About a quarter of a mile west of the east line of Section 23 the shale is found at the level of the flat, but rises to the west, and where it turns south along the west slope of the ridge, is 80 to 100 feet above the flat. As the length of the outcrop is not less than 1,200 feet, the width about 100 feet, and the average thickness about 25 feet, the available tonnage amounts to more than 75,000. The overburden consists of the green siliceous shale, and varying thicknesses of cherty limestone and loess. The total thickness of over- burden reaches 100 feet in places. The Mobile and Ohio Eailroad runs along the foot of the slope. Other Localities About one mile west of Mountain Glen, at the end of the ridge, in Southeast !/4 of Section 27, T. 11 S., R. 2 W., opposite the outcrop in the Northwest 14 of Section 34, the slope is gentle and covered with loess. The black shale undoubtedly underlies this loess, and should exploration show that it is feasible to move the latter, large quantities of shale might also be obtained here. Higher up the ridge, along the west slope, the black shale outcrops under conditions similar to those at the Northwest 14 of Section 34. Also at the end of the ridge, in the Southeast Vi of Section 10 (opposite the outcrop on the branch of Caney creek) , and at the end of the ridge in the west-central part of Section 14 (opposite State pond), similar conditions prevail. Where the black shale underlies the flats in the gaps, often at depths of less than 10 feet, other possible localities for commercial exploitation are afforded. In the event that the value of the black shale proves sufficient to warrant the use of mining methods in its recovery, the amount avail- able would be enormous. The shale probably underlies all the county east of its outcrop but becomes progressively deeper to the north and east. However, at nearly any point along the Mobile and Ohio Rail- road, from one mile northwest of Jonesboro to about one mile south- west of Mountain Glen, the black shale can be reached at depths rang- ing from 30 feet to not more than 100 feet. LOCALITIES MAINLY OF LOCAL IMPORTANCE In addition to the localities mentioned as possessing commercial possibilities, the whole shale belt thruout its extent should prove a source for local supply. Its position high up the slope and the broken character of the topography make it difficult of access even to wagons at the present time. However, roads can readily be built at least part of the way, and means can be devised to get the shale down to the more level country with the aid of gravity, in those localities where roads cannot be built all the way to the outcrops. 244 BULLETIN No. 232 [March, PART m FINELY-GROUND SHALE AS A SOURCE OF POTASSIUM FOR SOIL IMPROVEMENT BY EGBERT STEWAET, CHIEF IN SOIL FERTILITY* The World War created a potash, famine in America by cutting off supplies from the German potash deposits. The price of the potash reserve in America and the limited American supply became so great as to prohibit its use in agriculture. This condition, however, stimu- lated the search for American sources of supply, with more or less success. Reports of these efforts have been recorded in the various scientific and technical journals of the country. Early in 1915 the Department of Agronomy became interested in securing a cheap American source of potassium for use on the peaty lands of Illinois, which, as is well known, are markedly deficient in potassium and respond generously to its application. It seemed to the writer that there was no reason why the so-called insoluble potassium compounds, such as orthoclase felspar and leucite, if finely ground, could not serve as a source of potassium for crop production on such soils. It is true that finely-ground materials such as orthoclase felspar, leucite, and alunite, have been used in such a manner in the past, but these tests, particularly in America, have usually been made on soil that was not definitely known to be deficient in potassium, as is the peaty soil of Illinois and other sections of this country. In 1916, therefore, a series of greenhouse pot cultures was started with peaty soil treated with finely-ground leucite, kainit, alunite, and ignited alunite, in an ^ffort to determine the comparative value of these various forms of potassium for soil improvement. The peat was dried, thoroly mixed, and placed in four-gallon earthenware pots. The potassium content of the peat, alunite, leucite, and kainit was as fol- lows : peat, .3520 percent ; alunite, 8.91 percent ; leucite, 9.95 percent ; and kainit, 12.78 percent. The outline of the treatment is recorded in Table 4. Lime in the form of finely-ground limestone was applied at the rate of 60 grams per pot, or 5 tons per acre. The amount of potassium applied to each pot was the same, 1.34 grams (which is equivalent to an application of 500 pounds of potassium sulfate per acre). The amounts of the different materials supplying the potassium were as. follows : Alunite 15.05 grams Leucite 13.49 grams Kainit 10.50 grams *Doctor Stewart is now Dean of the College of Agriculture, University of Nevada. 1921] PART III: FINELY GROUND SHALE FOR SOIL IMPROVEMENT 245 TABLE 4. POT-CULTURE EXPERIMENTS WITH INSOLUBLE POTASSIUM ON PEATY SOILS Outline of Treatment, 1916 Pot No. SERIES I WHEAT SERIES II OATS SERIES III CLOVER 1 Lime Lime Lime 2 Lime Lime Lime 3 4 L, Kainit L, Kainit L, Kainit L, Kainit L, Kainit L, Kainit 5 6 L, Alunite L, Alunite L, Alunite L, Alunite L, Alunite L, Alunite 7 8 L, Leucite L, Leucite L, Leucite L, Leucite L, Leueite L, Leucite 9 L, Leucite Magnesium chlorid Sodium chlorid L, Leucite Magnesium chlorid Sodium chlorid L, Leucite Magnesium chlorid Sodium chlorid 10 L, Leucite Magnesium chlorid Sodium chlorid L, Leueite Magnesium chlorid Sodium chlorid L, Leucite Magnesium chlorid Sodium chlorid The magnesium chlorid and the sodium chlorid were applied to Pots 9 and 10 at the rate of 3.4 grams per pot. A peculiar condition at once developed. It was impossible to secure a normal growth of either wheat or oats in any of the pots, even where kainit was added. The wheat and oat plants would grow vigorously for five or six weeks, giving every evidence of marked im- provement from the applications of potassium material. At the end of that time they would invariably turn yellowish brown and no fur- ther growth would take place. The condition persisted thruout the entire four years of the experiment. As a result, corn and buckwheat were substituted for wheat and oats, with very favorable results. The yields obtained in 1916 are recorded in Table 5. The results obtained are very suggestive. Leucite gave yields which showed a distinct benefit from the treatment; the increases were 126 percent in the case of the corn and 60 percent in the case of the clover. Kainit gave an increase of 326 percent in the yield of corn and of 121 percent in the yield of clover. Alunite gave some indica- tions of being beneficial, especially in the production of corn. Its effect on clover, however, was negative. The addition of sodium chlorid and magnesium chlorid to the leucite in an attempt to produce an artificial kainit, was no more effective than the leucite itself. In 1917 two additional pots for the use of ignited alunite were added to the series. All pots received an additional treatment of potash-bearing material, as before. The results are reported in Table 6. 246 BULLETIN No. 232 [March, FIG. 3. BUCKWHEAT GROWING ON PEATY SOIL TO WHICH HAS BEEN ADDED THE MATERIALS INDICATED FIG. 4. COMPARATIVE EFFECT OF SHALE AND OTHER MATERIALS ON GROWTH OF BUCKWHEAT ON PEATY SOIL 1921] PART III: FINELY GROUND SHALE FOR SOIL IMPROVEMENT 47 TABLE 5. EFFECT OF VARIOUS FORMS OF POTASSIUM ON PRODUCTION OF CORN AND CLOVER, 1916 Yields recorded as grams per pot, air- dry weight Pot No. Treatment Corn Clover Individual Average Individual Average 1 2 3 4 5 6 7 8 9 10 .Lime 11 12 50 48 19 21 25 27 28 24 11.5 49 20 26 26 28 28 66 57 31 30 43 47 33 40 28.0 62.0 30.5 45.0 5*6.5 Lime L, kainit L, kainit L, alunite L, alunite L, leucite L, leucite L, leucite, sodium chlorid, magnesium chlorid L, leucite, sodium chlorid, magnesium chlorid TABLE 6. EFFECT OF VARIOUS FORMS OF POTASSIUM ON PRODUCTION OF CLOVER AND BUCKWHEAT, 1917 Yields recorded as grams per pot, air-dry weight Pot No. Treatment Clover Buckwheat Individual Average Individual Average 1 2 3 4 5 6 7 8 9 10 11 12 Lame 14 19 46 70 20 23 35 30 22 22 166 125 16.5 58.0 21.5 32.5 22.0 145.0 30 40 75 80 46 39 90 81 70 75 Not pla: buckw 35.0 87.5 42.5 85.5 72.5 ited to heat Lime L, kainit L, kainit L, alunite L, alunite L, leucite L, leucite L, leucite, magnesium chlorid, sodium chlorid L, leucite, magnesium chlorid, sodium chlorid Ignited alunite lernited alunite . Again the yields from the use of leucite were very favorable. Kainit gave an increase of 251 percent in the yield of clover and of 150 percent in the yield of buckwheat ; while leucite gave an increase of 98 percent in the yield of clover and of 143 percent in the yield of buckwheat. The ignited alunite, as was expected, gave remarkable increases, amounting to nearly 800 percent. 248 BULLETIN No. 232 [March, FIG. 5. EFFECT OF SHALE ON THE PRODUCTION OF RAPE FIG. 6. EFFECT OF SHALE ON THE PRODUCTION OF SWEET CLOVER 1921] PART III: FINELY GROUND SHALE FOR SOIL IMPROVEMENT 249 During 1918 various other crops were tested out with continued favorable indications for leucite. See Table 7. TABLE 7. EFFECT OF VARIOUS FORMS OF POTASSIUM ON THE PRODUCTION OF RAPE AND CLOVER, 1918 Yields recorded as grams per pot, air-dry weight Ka] je Clove r Individual Average Individual Average 1 1 ji 1I1O 100 74 2 Lime 95 97.5 75 74.5 3 L ktiinit 120 106 4 145 132.5 107 106.5 5 L, alunite 90 92 6 L, alunite 90 90.0 92 92.0 7 L, leucite 116 99 8 L, leucite 138 127.0 99 99.0 9 L, leucite, magnesium chlorid, sodium chlorid 112 106 10 L, leueite, magnesium chlorid, sodium chlorid 110 111.0 101 103.5 11 L, ignited alunite 103 158 12 L, ignited alunite 107 105.0 147 152.5 Kainit gave an increase of 35 percent in the yield of rape and of 43 percent in the yield of clover ; while leucite gave an increase of 30 percent in the yield of rape and of 32 percent in the yield of clover. In 1918 some new pots with fresh peat were used to start some new series for the production of other crops. The average results obtained with these crops during 1918 and 1919 are recorded in Table 8. TABLE 8. EFFECT OF VARIOUS FORMS OF POTASSIUM ON THE PRODUCTION OF VARIOUS CROPS, 1918 AND 1919 Yields recorded as grams per pot, air-dry weight 1>/vf ItJ 18 iyiy No. Treatment Barley Rape Beets 1 Flax Alsike clover 1 Lime 45 180 (540) 43 76 2 L kainit 95 240 (840) 62 95 3 L alunite 46 187 (660) 48 86 4 L, leucite 65 223 (800) 54 141 fields recorded as harvested, not air-dry. Again the indications are very favorable for the use of leucite. The increases produced by this material and by kainit, as expressed on a percentage basis, may be summarized as follows : 250 BULLETIN No. 232 [March, Percentage Increases in Yields Barley Kainit Ill Leucite . 44 Eape 33 24 Beets 55 48 Flax 44 25 Clover 25 86 These results, so favorable to the use of leucite as a source of potassium for soil improvement on peaty soils, were presented in March, 1919, to the Chemical Research Club of the University of Illinois. At this meeting Professor S. W. Parr called attention to the shale deposit in Union county, Illinois, and suggested in view of the results obtained with leucite, that the potassium in the shale might also be directly available for crop growth. Professor Parr kindly offered to furnish some of the shale for use in pot-culture tests, in the hope that the potassium which it contained would be at least as avail- able as that in leucite. The suggestion was gladly received and some new pots were provided for testing out the finely-ground shale as a source of potassium for crop production. The amount of potassium added in the form of the shale was the same as was added in the other potassium-bearing materials, 1.34 grams per pot. The results obtained from the use of the shale in comparison with those obtained from the other materials are recorded in Table 9. TABLE 9. EFFECT OF VAEIOUS FORMS OF POTASSIUM ON THE PRODUCTION OF VARIOUS CROPS, 1919 Yields recorded as grams per pot, air-dry weight Pot No. Treatment Sweet clover Eape Corn fodder Buck- wheat 1 57 86 67 38 2 55 84 66 34 3 L, kainit 65 106 91 62 4 L kuiii i t 63 108 94 59 5 L aluiiito 55 90 73 39 6 L, alunite 57 92 72 38 7 L, leucite 60 104 99 75 8 L leucite 60 110 106 65 9 L, leueite, magnesium ehlorid, sodium chlorid 58 94 79 64 10 L, leucite, magnesium chlorid, sodium chlorid 58 93 83 67 11 L ignited alunite 71 97 112 94 12 L ignited alunite 70 99 116 98 13 L shale 157 170 160 99 14 L. shale . 144 165 169 103 These results were unexpectedly favorable to the shale. Its applica- tion gave a larger increase in yield than did any other form of potassium, even larger than kainit or the potassium sulfate from the 1921] PART III: FINELY GROUND SHALE FOR SOIL IMPROVEMENT 251 ignited alunite. The shale produced an increase in the yield of sweet clover of 168 percent ; of rape, 96 percent ; of corn fodder, 146 per- cent; and of buckwheat, 180 percent. The differences in yields are truly remarkable. The effect of the treatment is perhaps more clearly brought out in the accompanying illustrations. Even with such a crop as corn, which is not well adapted to green- house work, the effect of the shale was astonishing, as may be seen by a study of the data in Table 10. TABLE 10. EFFECT OF KAINIT AND OF SHALE ON THE PRODUCTION OF CORN, 1919 Yields recorded as grams per pot, air-dry weight Pot No. Treatment Corn fodder 1 208 2 203 3 233 4 L kainit 225 5 404 6 L shale . 406 Here the shale actually produced an increase in the yield of corn fodder of 98 percent ; the corn on the shale pots grew so large that it was necessary to move it outside of the greenhouse. The effect of the shale on the production of corn is clearly shown in Fig. 1 (page 228). As is well known, there is another type of soil in Illinois, gray silt loam, which responds readily to the application of soluble potassium salts, altho the response is usually attributed to the effect of the soluble salt rather than to the effect of potassium as a plant food. There is some indication that the shale may serve as a source of potassium for such soils. Buckwheat and corn were grown in the greenhouse on this type of soil treated with kainit and shale. The results are recorded iii Table 11. TABLE 11. EFFECT OF KAINIT AND OF SHALE ON THE PRODUCTION OF WHEAT ON GRAY SILT LOAM, 1920 Yields recorded as grams per pot, air-dry weight Buckwhea t Pot No. Treatment Grain Straw Total crop fodder 1 Lime 22.50 59.30 82 143 2 Lime 22.10 60.90 83 146 3 L, kainit 26.90 69.10 96 181 4 L, kainit 2470 68.30 93 165 5 L, shale 31.00 72 (JO 103 154 6* L. shale . 28.20 71.80 100 158 252 BULLETIN No. 232 In the production of the buckwheat there was an increase of 32 percent in the yield of grain, and of 19 percent in the straw, from the use of shale. There was also a slightly increased yield of corn fodder from the application of shale. The buckwheat, in 1920, was grown on one of the original peat soil series. Alunite had shown very little effect ; so it was decided to use these alunite pots as checks this year and to apply fresh shale to the original check pots, Nos. 1 and 2, in order to eliminate the possible effect of fresh peat soil. Pots 13 and 14, receiving the shale, had been recently filled with peat, while the remainder of the series had been filled three years previously. It was thought that this difference might have had some influence on the remarkable effect of the shale, and so it was checked out as indicated. The shale on the original check pots raised the yield of buckwheat in 1920 slightly higher than in the original shale pots, Nos. 13, and 14. The complete data are recorded in Table 12, from which it is clearly seen that the effect above noted was due to the shale itself and not to the freshness of the peat soil. TABLE 12. EFFECT OF VARIOUS FORMS OF POTASSIUM ON THE PRODUCTION OF BUCKWHEAT, 1920 Yields recorded as grams per pot, air-dry weight Pot No. Treatment Individual Average 1 Lime (original check) shale this year 35 2 Lime (original check), shale this year 34 34.5 3 L kainit 22 4 L kainit 19 20.5 5 L alunite 12 6 L, alunite 10 11.0 7 L leucite 28 8 L, leucite 25 26.5 9 10 11 L, leucite, magnesium chlorid, sodium chlorid .... L, leucite, magnesium chlorid, sodium chlorid. . . . L ignited alunite .. 38 28 31 34.0 12 L, ignited alunite 21 26.0 13 L shale 35 14 L, shale 32 33.5 CONCLUSIONS This pot-culture work in the greenhouse indicates marked benefit to crops, resulting from applications of shale. The results are so striking and of such possible economic development as to warrant more extended investigations, particularly in the field; and they are of sufficient general interest to make advisable their presentation at this time. It is quite evident that the potassium in this shale can be directly used by crops in pot cultures under greenhouse conditions.