*:..'<' ^ '* x i THE UNIVERSITY OF ILLINOIS LIBRARY . ' * 630.7 it u; """ IA>O. I (y (3 I 15 I AGRIC ' . - 1 , UBFARY OF THE UNIVERSITY OF ILLINOIS N.QN CIRCULATING CHECK FOR UNBOUND CIRCULATING COPY UNIVERSITY OF ILLINOIS Agricultural Experiment Station BULLETIN No. RADIUM AS A FERTILIZER BY CTEIL G. HOPKINS AND WARD H. SACHS URBANA, ILLINOIS, JANUARY, 1915 SUMMARY OP BULLETIN No. 177 1. The properties of radium place it in the front rank among the remark- able discoveries of modern times. Page 389 2. Earlier investigations have shown that radium may affect the physio- logical processes of plants. Page 390 3. Some conclusions have been drawn from rather discordant data, to the effect that radium is a wonderful crop stimulant and that the application of radio-active material to the soil is a profitable procedure for the gardener or farmer. Page 391 4. A careful study of the data reported shows that the conclusions drawn and the claims made were not justified by the facts presented. Page 394 5. The trustworthy results from two years of field trials by the Illinois Experiment Station show that radium applied at a cost of $1, $10, or $100 per acre produced no effect upon the crop yields either the first or the second season. Page 395 6. Upon careful analysis of the known facts, radium, notwithstanding its wonderful energy, is found to afford no foundation for reasonable expectation of increased crop yields. Page 400 7. Both consumers and producers should stand for positive soil improvement and for permanent soil preservation, and opposed to soil depletion, land ruin, and ultimate farm abandonment. Page 400 RADIUM AS A FERTILIZER BY CYEIL G. HOPKINS, CHIEF IN AGRONOMY AND CHEMISTRY, AND WAED H. SACHS, ASSOCIATE IN CHEMISTRY With the discovery of radio-activity by Becquerel in 1896, and of radium itself by M. and Mme. Curie in 1898, science revealed a property of matter and a source of energy hitherto unknown; and the facts already established, the predictions or claims made, and the general interest in the subject seemed to justify an investigation under field conditions of the possible value of radium as a fertilizer, or of radio-activity as a crop stimulant. THE CHEMICAL ELEMENTS All matter is composed of chemical elements, which are considered permanent or indestructible, altho they may change their form physi- cally and may enter into various compounds chemically. Thus car- bon (C) occurs in the free state in the diamond, in graphite, and in coal. It also occurs in solid compounds, such as limestone (CaC0 3 ) and sugar (C^H^O^); in liquid form, as carbon disulfid (CS 2 ), benzene (C 6 H 6 ), chloroform (CHC1 3 ), etc.; and in many gases, such as carbon dioxid (C0 2 ), marsh gas (CH 4 ), acetylene (C 2 H 2 ). About eighty chemical elements have been found, but most of them are very rare and only ten are known to be essential for crop produc- tion. They are: carbon and oxygen, secured thru the leaves from the carbon dioxid of the air; hydrogen, from water absorbed by the roots; and seven elements secured from the soil nitrogen, phos- phorus, potassium, calcium, magnesium, iron, and sulfur. Legume crops may also secure nitrogen from the air by means of root-tubercle bacteria. THE PROPERTIES OF RADIUM Radium possesses most of the properties of a true chemical ele- ment, but it also possesses in most remarkable degree the peculiar and newly discovered property of spontaneous and continuous ema- nation of particles, and radiation of energy, called radio-activity. Radium is a solid substance, but it disintegrates or gives off particles of matter which further disintegrate, yielding as one final product the chemical element helium 1 (an inert gas). The speed with which J At least 98 percent of the total energy evolved by radium is due to the libera- tion of helium atoms, altho helium appears to constitute only about 10 percent of radium. (The remaining 90 percent is thought by some to be lead.) 389 390 BULLETIN No. 177 [January, the emanated helium particles are projected from radium is about 12,000 miles per second, compared with 186,000 miles per second as the velocity of ordinary light. The mass of radium is not permanent, but is reduced to one-half in about 1760 years, to one-fourth in 3520 years, to one-eighth in 5280 years, and so on. Radium continuously emits or radiates heat, light, and electricity. The amount of heat evolved is relatively enormous. A given quantity of radium emits sufficient heat to raise an equal weight of water from the freezing point to the boiling point in less than one hour, and this radiation of heat continues hour after hour, with gradual reduction to one-half the quantity in about 1760 years. Thus the total quantity of heat ultimately evolved by a pound of radium would be sufficient to raise more than fifteen million pounds of water from freezing to boiling temperature, whereas a pound of good Illinois coal has power to change only seventy-five pounds of water from freezing to boiling. In other words, one pound of radium would ultimately furnish more heat than one hundred tons of coal; and in total ultimate energy 1 (including heat, light, electricity, etc.) one pound of radium would be equivalent to more than one hundred fifty tons of coal, or to more than seventy thousand horse-power days of twenty-four hours each. On the other hand, the total energy of a quantity of coal can be secured almost instantly, whereas the rate of disintegration of radium is fixed, so that only half its total energy becomes liberated in about 1760 years; but, expressed in terms of continuous work, about nine pounds of radium would be equivalent to one horse-power. 2 SOME EARLIER EXPERIMENTS Many experiments have been made to ascertain the effect of radio- activity on plant growth; and in general it has been found that a distinct influence is exerted if sufficient radium is used, altho some experimenters report negative results. In summarizing his investigations in the Popular Science Monthly, Volume 74, pages 222-232, Gager states that radium acts under certain conditions as a stimulus to physiological processes of plants, but that it may retard or inhibit development, or even kill the plant, if used in too great strength or for too long a period. Acqua, an Italian in- vestigator, reports retarded root development, but little or no direct investigations show that one gram of radium emits enough heat to raise 118 grams of water one degree centigrade in one hour, or 118 calories, and indicate enough total energy to decompose one gram of water into hydrogen and oxygen every twenty-four hours, equivalent to 3822 calories, or nearly 160 calories per hour. 2 Roscoe and Schorlemmer, Treatise on Chemistry (1913), Volume II, page 1423, state that "it appears that one pound of radium emits energy at the rate of 10,000 horse-power"; but they have evidently compared radium energy per day with horse-power per second, and, since there are 86,400 seconds in a day, the corrected comparison shows about one horse-power for 8.64 pounds of radium. 1915] RADIUM AS A FERTILIZER 391 effect upon stems or leaves. Fabre, a French scientist, found some beneficial effects from radio-activity corresponding to emanations of one and one-half microcuries 1 for each two liters* of air, but injury from greater strength. Efforts are already being made to add radio-active substances to the list of commercial fertilizers and stimulants that farmers are urged to buy, and this preliminary report is issued in order that the information thus far secured may be available to those who are in- terested and who might otherwise be led to waste money that should be invested in rational soil enrichment. RUSBY'S EXPERIMENTS In the New York Times of October 25, 1914, a full page is devoted to radium as "A Wonderful Stimulant of Farmers' Crops." This article, with its illustrations and data, is credited to H. H. Rusby, M. D., of the Columbia University College of Pharmacy. The fol- lowing statements are direct quotations : "In October, 1913, I arranged with the Standard Chemical Company of Pittsburgh, Penn., to make preliminary trials on an extensive scale. In view of the cost of radium and its preparations, the reader may wonder how such an ex- periment could be undertaken. It requires about 400 tons of radium ore of stand- ard quality to yield a gram, about fifteen and a half grains, of radium, which amount could easily be carried on a man's thumb nail. The regular market price is $10,000 a grain, or $120,000 a gram, equal to $70,000,000 a pound. This prob- lem was solved by making use of the finely powdered residue remaining after all the radium possible has been extracted, but leaving some two or three milligrams to the ton, worth some $300, yet a by-product unless a special use for it could be discovered. ' ' "That the application of such material to the soil is a profitable procedure for the gardener or farmer may be understood when it is seen that such increases in production resulted as 29 per cent, in lettuce, 17 per cent, in lima beans, 35 per cent, in cucumbers, 35 per cent, to 44 per cent, in different varieties of squash, 80 per cent, in Rocky Ford muskmelon, 24 per cent, in carrots, 50 per cent, in sweet corn, and 70 per cent, in radishes, and that nearly all vegetables are won- derfully improved in their table qualities." "My experiments and observations included the winter culture of radishes in a market gardener's greenhouse, some seedlings in window boxes in my own home; field crops covering more than one hundred acres at Northfield, Ohio, under the direction of W. W. Darling; an experimental garden at Pittsburgh, and the plantation of an acre and a half at Nutley, N. J., of which I have had imme- diate personal charge throughout the season." J A microcurie is a millionth part of a curie, the unit of measurement for radio-activity, which is the quantity of radium emanation in equilibrium with one gram of radium. In other words, the curie (named from the discoverers) repre- sents the constant or continuous energy of one gram of radium. 2 A liter holds 1,000 cubic centimeters, or 1,000 grams of water; it is about one quart, and corresponds to about a 4-inch cube, or 64 cubic inches. On the basis of one and one-half microcuries for each space four inches square and eight inches high, this application corresponds to 588,060 microcuries, or 588 milligrams of radium, per acre of land. 392 BULLETIN No. 177 [January, POUNDS OP PKODUCE EEPORTED FROM EADIUM EXPERIMENTS AT NUTLET, N. J. Applied per Acre Ore Ta Badiun ilings (B. A. F.), Ibs 200 .25 100 .12 50 .06 25 .03 i, milligrams Plot Nos AA BB CC DD X j. 2 2 3 3 4 4 5 5 6 7 8 9 10 11 12 13 14 15 16 17 18 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 Early Celery (No data) Telephone peas 21 13 32 4 133 85 160 169 181 8 4 21 16 31 9 132 104 160 226 270 8 6 23 15 26 11 133 138 118 242 309 9 4 19 21 35 16 126 118 120 213 293 10 3 22 16 27 16 133 111 153 267 330 7 5 Second crop, Cow Horn Turnips (No data) Nott 's peas Second crop, Globe Turnips (No data) Lettuce Second crop, Savoy Cabbage (No data) Second crop, Late Celery (No data) Beets . . Carrots Esrer Plant . Late Tomatoes Early Tomatoes Cucumbers . Cucumbers small Cucumbers total 12 33 14 54 14 35 28 57 81 56 243 412 92 404 232 16 80 233 92 103 83 340 13 33 24 64 78 65 321 388 82 458 150 13 90 226 90 116 72 378 13 30 29 66 71 66 222 280 93 420 100 13 95 258 95 68 50 333 12 31 29 65 58 61 206 349 80 405 162 13 63 188 88 73 46 269 String Beans Early Peppers Onions (No data) Parsnips (No data) Navy Beans (No data) Red Kidney Beans (No data) Turnip Radish Second crop, Late Celery (No data) Long Radish Second crop, Late Celery (No data) Early Eose Potatoes 48 277 384 68 460 185 19 81 . 217 95 87 39 370 Pumpkins Early Cabbage Dwarf Lima Beans Late Cabbage Hubbard Squash Crimson Clover (No data) Late Peppers Late Corn Delicious Squash Queen Potatoes (No data) Early Corn Hackensack Muskmelons Eocky Ford Muskmelons Watermelons . 1915} RADIUM AS A FERTILIZER 393 "In Mr. Flannery's garden I particularly noted the great gain of turnips and beets under the radium influence over those without it." "The growing crops, which I have observed with great care on various occa- sions, have shown results in all respects similar to those recorded at my Nutley plantation, which I shall now describe." "One plot, AA, was treated with radio-active fertilizer at the rate of 200 pounds to the acre; another, BB, with 100 pounds; a third, CO, with 50 pounds; DD, with 25 pounds, and X, with none. Each set of plots was nineteen feet wide, and the plots composing the sets were, respectively, five, thirteen, nine, or twenty feet by nineteen feet, according to the nature of the crop. Each plot was separated from those on its four sides by paths three feet wide, except for the central road, which was six feet wide." "In the accompanying table each plot is indicated by the number of pounds of E. A. F. (radio-active fertilizer) that it received to the acre." '"' In~conclusion, it may be stated that the yield of most crops can be in- creased by the addition of some amount of radio-active fertilizer, the amount differing with different crops. The beneficial effects continue over successive crops, probably for many years. The largest amount required by any crop would cost less than the increased market value of such crop of the first year. ' ' "The fertility of unused ground will spontaneously increase at a much greater rate when treated by radium." It is to be noted that Rusby credits the ore tailings with the same radium content (about 2y 2 milligrams per ton) as the original ore (1000 milligrams in 400 tons) ; but it is easily possible that the by- product for which the Standard Chemical Company desires to find a market is as rich in radium as the ore itself ; and the fact that Mr. J. M. Flannery is president of the Standard Chemical Company lends special interest to the results observed "in Mr. Flannery's garden," showing ' ' the great gain of turnips and beets under the radium influ- ence," altho the beets on Plot 6 at Nutley (see table) show slightly decreased yields in two cases and no benefit in the other two. The complete data are not reported for turnips at Nutley, but Rusby states that the radium influence from the 25-pound application of ore tailings even crossed the 3-foot path and made the turnips on that (south) end of the untreated plot "twice as large and strong as those at the northern ends. ' ' He adds the following : "There is an exactly similar difference among the turnips in the 25-pound plot, those at the southern ends of the rows, separated by 3 feet from the 50-pound plot, being twice as large as those at the northern ends, with the same regular gradation. Between the 50-pound and the 100-pound plots there is little differ- ence, showing that 50 pounds (.06 milligram of radium per acre) produces about the maximum effect on turnips. "Between the 100 and the 200-pound plots, however, there is a similar but re- verse relation. The turnips in the 200-pound plot are stunted by an excess of radium, just as was the spinach that occupied the same plot 1 in the early spring. ' ' *The published diagram of the experimental plots at Nutley, N. J., shows that the spinach was followed not by turnips but by late celery, and that turnips were grown only after peas. In the accompanying tabular statement will be found all of the data reported (expressed in even pounds per plot), and also in- formation concerning the order of planting on the various plots, as shown in the diagram; but the data for potatoes may have been secured from Plot 30 instead of Plot 20; otherwise the original publication is clear. 394 BULLETIN No. 177 [January, No information is given as to the amount of radium applied for turnips on Mr. Flannery's garden, but it is of interest to note that Fabre reports beneficial results on plant growth from radium up to 588 milligrams per acre, or more than 2000 times the amount Rusby found to be injurious for turnips. A careful study of Kusby 's data suggests that all of the differences which he records may have been caused by natural variations in the soil or other influences, rather than by the radium. Thus his report of 29 percent increase in lettuce is based on Plot DD, but the ad- joining plot, CO, shows 4 percent decrease. The 17 percent increase reported for lima beans is based upon Plots BB or DD, but the inter- mediate plot, CC, shows only 3 percent increase, while AA shows 15 percent decrease. The 35 percent increase reported for cucumbers is based only upon the larger size from Plot DD, but the small cucumbers show 40 percent decrease on the same plot, and the total crop shows little ef- fect none with the heaviest application. To find 35 and 44 percent increases for squash, one must figure results from 25 pounds of ore tailings with Delicious squash, and from 100 pounds of ore tailings with Hubbard squash; whereas the check plot, X, produced 62 per- cent more Hubbard squash than where 25 pounds of ore tailings were applied. In other words, the minimum application seems to have increased markedly the yield of Delicious squash, but appears to have stunted in a marked degree the growth of Hubbard squash. The increases claimed with muskmelons, carrots, sweet corn, and radishes are also found only by selecting the highest results from rather discordant data. "With nearly all of the crops reported upon, radium appears to have decreased the yields in some of the trials, but neither increase nor decrease correlates in any general way with the amount of radium applied. The smallest yield of Hackensack muskmelon was with the smallest application, while the smallest yield of Rocky Ford muskmelon was with the largest amount of radium. These extremes gave equal yields of early corn but very different re- sults with late corn. The four trials with carrots show two increases and two decreases, with an average of 111 pounds, exactly the same as with no radium. One variety of radish appears benefited, the other stunted, by equal amounts of radium. Likewise, 25 pounds of the ore tailings helped one kind of peas and hindered the other, while 50 pounds produced similar effects but in the reverse order ; and 200 pounds gave 50 percent increase with late peppers and 50 percent decrease with early peppers. Among the fifty-nine trials for which data are reported on one half of the field (Plots 1 to 20), thirty-eight show no benefit from ra- dium; while on the other side of the "central road" thirty-nine of the forty-eight trials show benefit. In other words, the influence of radium was usually beneficial on one side of the road and usually in- 1915} RADIUM AS A FERTILIZER. 395 jurious on the other side, which certainly strongly suggests that the variations in yield of crops were due to some other differences than radium applications. Busby's statement that "the fertility of unused ground will spon- taneously increase at a much greater rate when treated by radium" appears to be an opinion, not an established fact. ILLINOIS EXPERIMENTS In the spring of 1913, thru the kindness of the Standard Chemi- cal Company of Pittsburgh, the University of Illinois Agricultural Experiment Station was enabled to begin a series of field experiments with radium as a fertilizer or crop stimulant. This company re- ported 1500 tons of uranium-radium ore (carnotite) as the annual product from its Colorado mines, and was said to be the only concern manufacturing radium salts in America. The company was deeply interested in having the experiments conducted, and the radium salts furnished to us were prepared under the direction of Dr. Otto Brill and Dr. Charles H. Viol of the radium research laboratory of the Standard Chemical Company, the quality and strength of the prepara- tions being thus assured. Since the "radium plots" were made to run crosswise over other regular experiment plots, these investigations were conducted with- out interfering with our other experiments, and at small extra ex- pense, chiefly for taking weights of produce "in both directions," the expense of applying the radium having been borne by the Stand- ard Chemical Company. The value of radium is about $100 per milligram; and it may well be noted that it takes 453,600 milligrams (453.6 grams) to make one pound. The total amount of radium thus far secured in all the laboratories and factories of the world is estimated at eight grams, or less than one-third of an ounce. In order that the field investigation might have direct relation to practical Illinois agriculture, the radium was used at three rates of application, costing, respectively, $1, $10, and $100 per acre; or in amounts of .01 milligram, .1 milligram, and 1 milligram of radium per acre. If the effect of the applications should be marked and per- manent, even the initial expense of $100 per acre might be desirable. The fields selected for these experiments were the north division of the Series 200 and the south division of the Series 600 of the Agronomy plots on the South Farm of the University of Illinois. Each of these fields contains eighteen fifth-acre plots, two rods wide and sixteen rods long, besides some division and border strips, making each field sixteen rods wide east and west, and thirty-eight rods long north and south. For the radium experiments each field was divided transversely into eight plots two rods wide and thirty- 396 BULLETIN No. 177 [January, eight rods long, numbered one to eight, from west to east. No radium was applied on Plots 1 and 5 ; where applied, the rates per acre were .01 milligram on Plots 2 and 6, .1 milligram on 3 and 7, and 1 milli- gram on 4 and 8. On Series 200 and on the west part of Series 600, the radium was applied in a solution of radium barium chlorids diluted with distilled water, the check plots receiving the same quantity of distilled water without radium. On the east part of Series 600, solid radium barium sulfates were applied after being diluted by thoro mixing and pul- verizing with dry soil from the field, the check plot receiving the same weight of soil without radium. The pulverized soil was applied with a force-feed grain drill, and the solutions with an Aspinwall bar- rel sprayer. For the heaviest applications, only 528 cubic centi- meters of the solution of chlorids and 770 grams of the sulfates were required per acre, amounts which are too small to produce appre- ciable indirect effects, such as might possibly be caused by 100 pounds or more of crude salts per acre. On both fields corn was grown in 1913 and soybeans in 1914. In the accompanying tables are reported the yields per acre in bushels, except where soybean hay was harvested, which is reportd in pounds per acre. Owing to other experimental work involving some varia- tions in planting, only part of Series 600 furnished comparable data in 1913, only twenty-four separate trials being provided, as shown in Table 3. . Aside from the corn grown on Series 200 in 1913, the average re- sults reported in the tables are considered trustworthy within the limits of variation shown. TABLE 1. CORN ON SERIES 200, 1913 (Bushels per acre) Radium per acre, mgs. . . .01 .1 1 .01 .1 1 Plot Nos. ... 1 2 3 4 5 6 7 8 241-2 29.6 33.6 40.0 38.9 36.1 35.5 33.7 35.6 243 38.2 36.0 41.9 45.4 39.6 39.3 38.6 40.6 244-5 34.5 43.6 38.9 41.8 31.1 40.8 48.7 41.1 246 43.8 38.0 43.0 45.8 42.6 48.8 48.1 50.2 247-8 40.1 39.0 41.1 39.9 36.5 43.0 41.4 43.4 249 48.5 40.7 52.5 54.9 52.1 46.3 46.4 46.3 250 49.1 45.2 49.9 52.5 51.4 44.4 35.9 34.5 251-2 51.1 46.6 39.8 37.1 42.3 42.2 45.6 46.6 253 44.1 45.9 53.1 45.7 45.4 53.3 62.6 62.6 254-5 49.2 49.6 48.4 55.3 63.7 67.7 67.8 66.6 256 43.5 40.0 46.2 45.8 54.1 61.8 57.3 66.2 257-8 34.4 36.0 43.1 50.6 54.7 54.2 59.6 58.0 Average 42.2 41.2 44.8 46.1 45.8 48.1 48.8 49.3 Average gain 2.6 3.9 2.3 3.0 3.5 Average loss 1.0 1915] RADIUM AS A FERTILIZER 397 TABLE 2. SOYBEANS ON SERIES 200, 1914 (Bushels per acre) Radium per acre, mgs. . . .01 .1 1 ,01 .1 1 Plot Nos. ... 1 2 3 4 5 6 7 8 241-2 18.8 19.1 20.8 20.3 19.5 19.4 19.8 20.5 243 22.5 20.9 21.7 22.3 18.9 19.3 20.6 21.5 244-5 26.0 27.3 22.4 23.0 22.7 24.4 25.6 22.2 246 28.9 25.5 25.2 23.5 21.9 26.3 27.0 24.8 247-8 28.9 28.9 29.4 27.3 23.7 24.8 24.2 23.5 249 28.7 28.5 28.0 30.2 25.8 26.7 25.1 23.3 250 28.4 28.8 28.7 27.6 25.8 26.7 23.1 21.1 251-2 25.3 29.7 29.5 26.6 24.0 26.6 28.3 27.0 253 27.0 26.9 27.9 26.2 25.8 28.5 29.3 29.8 254-5 25.3 24.5 24.8 24.9 24.8 28.0 28.3 26.9 256 26.2 24.3 28.1 27.7 26.1 28.5 29.4 29.5 257-8 22.0 17.6 23.0 26.0 27.6 24.8 28.7 29.1 Average 25.7 25.2 25.8 25.4 23.9 25.3 25.8 24.9 Average gain . .1 1.4 1.9 1.1 Average loss . . .5 .2 TABLE 3. CORN ON SERIES 600, 1913 (Bushels per acre) Planted 2 kernels per hill 3 kernels per hill Radium per acre, mgs. . .01 .1 1 .01 .1 1 Plot Nos. .. 1 .2 3 4 5 6 7 8 Hills 33 by 36 inches N. half, A 33.2 33.2 29.6 27.0 N. half, B 37.3 34.1 28.3 32.3 S. half, A 36.6 38.7 28.8 25.8 S. half, B 33.1 34.5 24.1 24.7 Average .... 35.0 35.1 27.7 27.4 Hills 33 by 39.6 inches N. half, A 31.6 34.0 28.3 27.4 N. half, B 32.8 36.5 31.8 34.2 S. half, A 34.1 32.6 26.1 26.6 S. half, B 32.6 31.4 25.7 18.7 Average . . . 32.8 33.6 28.0 26.8 Hills 33 by 44 inches N. half, A 33.3 30.3 28.2 28.1 N. half, B 30.9 28.9 24.9 27.2 S. half, A 33.5 38.7 27.6 29.3 S. half, B 27.2 33.6 26.7 20.4 Average . . . 31.2 32.9 26.9 26.3 .1 .8 1.7 Average loss . . .3 1.2 .6 398 BULLETIN No. 177 [January, TABLE 4. SOYBEANS ON SERIES 600, 1914 (Bushels per acre) Radium per acre, mgs. . . .01 .1 1 .01 .1 1 Plot Nos. .. 1 2 3 4 5 6 7 8 661 20.3 15.4 15.9 17.3 14.8 17.7 15.6 16.5 662 18.2 17.5 15.2 17.1 16.6 16.0 15.6 13.9 663 20 ;5 20.6 19.7 19.7 17.7 17.9 18.1 21.6 664 16.4 16.3 16.5 16.1 15.0 15.4 15.5 17.9 665 20.5 19.7 19.1 16.5 16.6 15.5 17.2 19.3 666 17.7 23.1 18.5 20.3 17.4 19.3 17.3 19.1 667 21.5 20.7 22.3 18.2 17.7 19.2 18.5 21.7 668 28.4 29.5 28.1 26.8 23.6 24.6 23.7 24.6 669 20.4 18.9 18.7 18.0 17.4 19.9 19.7 21.5 Average . . . 20.4 20.2 19.3 18.9 17.4 18.3 17.9 19.6 Average gain 1.0 .5 2 2 Averaere loss .2 1.1 1.5 TABLE 5. SOYBEAN HAY ON SERIES 600, 1914 (Pounds per acre) Radium per acre, mgs. . .01 .1 1 .01 .1 1 Plot Nos. .. 1 2 3 4 5 6 7 8 670 671 672 673 674 675 676 677 678 3833 4839 3578 3480 3470 3372 3289 3132 3833 4079 5099 3802 4039 3925 3354 3914 3110 4000 3036 4693 2849 3372 2883 2984 3332 4016 4416 2922 4841 2789 3458 2629 3024 3247 3300 4685 2874 4245 2410 3045 2337 2682 3082 2944 4054 2862 4382 2302 2902 2184 2753 2891 2912 4368 2754 4160 2192 2912 1915 2888 3054 2889 4241 2883 4041 2335 2992 2335 2796 3225 3090 4359 Average . . . 3647 3925 3509 3433 3075 3062 3000 3117 Average gain . 275 42 Average loss . . 138 215 13 74 VARIATIONS DUE To DROUTH Series 600 possesses an unusually satisfactory degree of uniform- ity; but on Series 200 there are some topographic variations which influence the rapidity of the "run-off" or absorption of rain; and in very dry seasons, with occasional dashing showers, when moisture is a factor of great importance, these variations appear in the crop yields. From April 11 to September 11, a period of five months, the total rainfall in 1913 was only 5.87 inches. Under these adverse conditions, even the average results from Series 200 are not considered trust- worthy, notwithstanding the large number of separate trials making the averages. Considering even the general averages, .01 milligram of radium appears to have decreased the yield of corn by 1 bushel on the west part of the field and to have made 2.3 bushels increase on the east 1915] RADIUM AS A FERTILIZER 399 part. Again, increasing the cost of radium from $1 to $10 per acre appears to have increased the yield by 3.6 bushels on the west part and by only .7 bushel on the east part ; and the further increase of $90 shows apparent gains of 1.3 bushels on the west and only .5 bushel on the east part of this field. Of course no conclusions should be drawn from such discordant plus and minus results. TRUSTWORTHY DATA The results with soybeans on Series 200 in 1914 agree within nar- row limits in showing no benefit from the radium applied the year before, the west half of the field giving slightly smaller and the east half slightly larger average yields where radium was added than on the check plots. On Series 600 the average yields of corn in 1913 were slightly larger with two kernels per hill and slightly smaller with three ker- nels per hill where radium was applied, but the apparent gains and losses are all well within the experimental error or plot variation, and the general average indicates no effect from the radium. The yields of soybean seed on the north half of this field in 1914 likewise reveal no influence from radium, all rates of application indicating, on the average, slight decreases for radium on the west side and slight in- creases on the east side of the field With the soybean hay the six gen- eral averages show no effect from radium, four results being slightly below the checks and the other two slightly above. Thus from the two years' work we have six trustworthy average results with corn (Table 2), three "for" and three "against" radium, and we have eighteen averages with soybeans (Tables 3, 4, and 5), nine "for" and nine "against" radium. In all of these trials the average variation from the checks is so slight and so evenly distrib- uted, "for" and "against," as to lead only to the conclusion that ra- dium applied at a cost of $1, $10, or $100 per acre produced no effect upon the crop yields either the first or second season. EFFECT OF STIMULANTS Even if radium or other radio-active substances were to increase crop yields when applied to soils in sufficient quantity, 1 the effect would be that of a stimulant and the increase would be secured at the expense of the soil. Thus the soil would not be enriched in fertility, but actually impoverished by such treatment. This result follows also for all forms of proposed stimulation for soil or crop. 1 The rate of application mentioned by Fabre (heretofore referred to) would cost about $58,800 per acre at present prices for radium; and even his beneficial results lack general verification by other experiments. 400 BULLETIN No. 177 [January, Thus the use of electricity has been advertised by commercial in- terests, and many experiments have been conducted with the growing of crops under a network of electric wires. However, a careful study of the results reported from such investigations when conducted by public-service institutions reveals no important effects upon plant growth, altho some most remarkable results have been reported by investigators employed by commercial interests. Even the increased yield sometimes secured by excessive cultiva- tion is at the expense of the soil. The trustworthy information thus far secured in Illinois does not show profitable results from extra deep tillage, or from subsoiling, either with subsoil plows or with dynamite ; but even if such practices were temporarily profitable, they might not be advisable, because they tend to make soils poorer, and the same expense in limestone, phosphate, clover, or manure, which are highly profitable on our common soils, would tend toward positive soil en- richment and permanent preservation of fertility. These facts and principles deserve the most careful consideration, for they are of permanent interest to consumers as well as producers, and to industry and commerce as well as to agriculture. The people of the state and of the United States should stand as a unit for soil building and soil preservation, and opposed to soil depletion, land ruin, and ultimate farm abandonment. MISLEADING CLAIMS As a rule, the claims for possible stimulants are not well founded. Even radium, with all its wonderful energy, is found, upon careful analysis of the known facts, to afford no foundation for reasonable expectation of increased crop yields, when financial possibilities are considered. It is true that the total ultimate energy developed in 1760 years from a pound of radium will be equivalent to seventy-five tons of coal, or to 35,000 horse-power days of twenty-four hours each ; but when the time is reduced to one hundred days of good crop-grow- ing weather, and the amount of radium reduced to ten milligrams, costing $1,000 per acre, then the energy emitted from the radium for the possible benefit of an acre of corn during the crop season would be equivalent to one horse-power for only twenty-two seconds; and the heat evolved by $1,000 worth of radium on an acre of land in one hundred days would be less than the heat received from the sun on one square foot in thirty seconds. RATIONAL SOIL ENRICHMENT The only materials which need be added to the most common Illi- nois lands for their positive and permanent enrichment are lime- stone, phosphorus, and organic matter. These are the only necessary 1915} RADIUM AS A FERTILIZER 401 materials which are not provided naturally in inexhaustible supply. Of course the organic matter supplies the nitrogen, whether applied as farm manure or in crop residues and legume crops plowed under. On soils subject to much erosion, the application of phosphorus is usually not profitable or necessary, since the supply is renewed from the subsoil. On peaty swamp soils and on some sand lands, potassium is needed; but the normal lands of the state contain in the plowed soil of an acre from 25,000 to 35,000 pounds of potassium (from 30,000 to 40,000 pounds of potash), and in rational systems of farming, the addition of commercial potassium on such lands is unnecessary, un- profitable, and unwise. In a word, the well-informed farmer on the common Illinois land will purchase and apply limestone and phosphate; but he will grow the organic matter on the farm, secure nitrogen from the inexhausti- ble supply in the air, and liberate potassium from the inexhaustible supply in the soil; and he will not waste his money on so-called "complete" fertilizers, nor on newly advertised soil or crop stimu- lants. For further information concerning rational soil improvement, see Circulars 110, 149, and 165, which will be sent free of charge upon request; and, if so desired, the applicant's name and address will be placed upon the permanent mailing list for future publications by the Agricultural Experiment Station, Urbana, Illinois. UNIVERSITY OF ILLINOIS-DRBANA Q 630.7IL6B C001 BULLETIN. URBANA 166-181 1914-15 30112019528436 df*^ *J >> x* 1 '"?' ** , - < ff _ ^ IS' * ' 1