Κ. D. JACOB Soil and Water Conservation Research Division, Agricultural Re search Service, U. S. Department of Agriculture, Beltsville, Md.
Fifty Years of Fertilizer Progress I HE
ORGANIZATION
AMERICAN
of
the
CHEMICAL SOCIETY'S
in
1909
Di
vision of Fertilizer Chemistry is convincing evidence that 50 years ago fertilizer manufacture was al ready prominent among the na tion's industries. In the same year, fertilizers received editorial mention in the very first issue of INDUSTRIAL AND ENGINEERING CHEMISTRY.
Sub
sequent progress in fertilizer chem istry and technology has been re corded in this journal and the Society's other publications. I n 1908, the domestic consump tion of commercial fertilizer totaled 4,449,000 tons of products contain ing 667,000 tons of the principal plant nutrients (Ν, Ρ2Ο5, K 2 0 ) and having a retail value near $128,000,000. T h e close of the next half-century found American farmers using about 5 times this quantity of fertilizer which supplied 9.5 times as much nutrients at only 8.8 times the cost—an achievement to which chemists and chemical engineers m a d e important contributions. Research in the domestic fertilizer industry was still at a very low level 50 years ago. T h e chemist's role was chiefly in the field of routine analysis, and opportunities for chem ical engineers were few, indeed. Low-analysis materials from natural organic sources accounted for more than half of the commercial fertilizer nitrogen (107,000 tons in 1908), while Chilean nitrate and am monium sulfate supplied nearly all
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of the remainder. Chemical proc essing was confined chiefly to the manufacture of acid phosphate (nor mal superphosphate) and kindred products—in much the same way as in the preceding 50 years—which furnished most of the P 2 O s (400,000 tons). T h e potash (K2O) consump tion (160,000 tons) was almost entirely in the form of salts imported from Germany. However, techno logical developments were already under way, mostly in Europe, which foreshadowed revolutionary changes in the industry. Nitrogen at Century's Turn T h e future of nitrogen supplies was the paramount problem in fertilizers at the close of the 19th century. T h e apparent seriousness of the situation was emphasized forcefully in an address by Sir William Crookes. Crookes' address was certainly a factor in so spurring the interest of the scientific and technical world that manufacture of nitrogen ferti lizers from the air was realized in less than 10 years. Thus, Kristian Birkeland and Samuel Eyde accom plished the first successful operation of the electric-arc process in a full-size commercial plant in 1905 at Notodden, Norway. At about the same time the calcium cyanamide process, based chiefly on the research of Adolph Frank and Nikodem Caro, gained commercial operation in Germany and Italy. Fixation of nitrogen in the Western Hemisphere began on a permanent basis with the opening of the cyanamide plant in Niagara Falls, Ont., late in 1909. Favored by an a b u n d a n t supply of cheap electricity, Norway con tinued to be the principal locale of the arc process until its complete abandonment in 1939, largely be
INDUSTRIAL AND ENGINEERING CHEMISTRY
cause of its very high energy require ment—some 65,000 kw. - hr. per metric ton of nitrogen fixed. O n the other hand, cyanamide manu facture—with an energy require ment less than one fourth that of the arc process—is still a factor in the nitrogen-fixation industry. Direct Synthesis of Ammonia By 1909, the basic research of Fritz Haber and coworkers, Walther Nernst, and others, had established the conditions favoring the catalytic synthesis of ammonia by direct union of nitrogen and hydrogen under high pressure. These studies and the pio neering work of Carl Bosch, Alwin Mittasch, and their associates resulted in the development of the first prac tical process of this kind and its ap plication on a commercial scale at Oppau, Germany, in 1913, an ac complishment which, in the words of Harry A. Curtis, "stands out as one of the most brilliant achieve ments in the history of the chemical industry." T h u s was initiated a process which by 1958 had gained world-wide use and was furnishing the greater portion of the total supply of fixed nitrogen (around 8,500,000 tons) for fertilizer and other purposes. At the end of 1957 the synthetic ammonia facilities operating or under construction in the United States alone comprised some 55 plants with a total capacity exceeding 4,000,000 tons, of nitrogen per year. And if you want further proof of the growth curve of ammonia, look at the pro duction in 1909—8000 tons and then look at 1957's production—3,711,000 tons. Especially significant in the devel opment of the ammonia industry was the work of the Fixed Nitrogen Re search Laboratory established in 1919 by an order of the Secretary
one most i m p o r t a n t change has been the great progress, since 1940, in the manufacture of granulated mixtures. Requiring special processes a n d equipment, this development is rapidly gaining major status. T h e manufacture a n d use of liquid mixed fertilizers a n d fertilizer-pesticide mixtures has developed mostly since 1950. C o m p a r e d with solid products, liquid mixtures a p p e a r to have the a d v a n t a g e of lower capital investment a n d labor costs, and the problems of physical condition and uniformity of composition are less difficult. Before 1925, the average concentration of the three principal plant nutrients in mixed fertilizers had been about 1 4 % for at least 45 years. Subsequently, the average has increased steadily, especially since World W a r I I , to 2 9 . 5 % in 1957. This change has m a d e possible huge savings in manufacturing, handling, transportation, a n d a p plication costs per unit of nutrients, a n economy which is reflected in the fact that relative to costs in 1910-14 the index n u m b e r of the price paid for fertilizer by the American farmer during the last decade has averaged only about 6 0 % of the index for all commodities bought for use in farm production. While this progress involved the efforts of people in, m a n y fields, m u c h credit must be given to the research of the chemist a n d the agronomist, not the least of which were the extensive studies of the properties of concentrated fertilizer materials a n d their behavior in mixtures conducted in the U . S. D e p a r t m e n t of Agriculture u n d e r W. H . Ross (1915-45). Looking A h e a d
As the world will become increasingly d e p e n d e n t on commercial fertilizers to provide the food requirement of its expanding population, the outlook for the fertilizer industry appears to be promising, indeed. E a c h nutrient element performs specific functions in the growth a n d fruiting of plants, which brook n o substitutes. T h u s , unlike so m a n y other manufactured commodities, the essence of fertilizers is not subject to change, though its forms m a y differ greatly. T h e potentiality for the domestic industry is indicated by the fact that the current average use of the three principal plant nutrients in Western E u r o p e
Nitrogen-rich ammonia is a p p l i e d to growing crops b y injection into the soil
totals about 49 pounds per acre of agricultural land (including land u n d e r tree crops and p e r m a n e n t meadows and pastures), as compared with only 11.5 pounds in the United States. T h e years ahead will see important advances in the technology of fertilizers a n d in the economy a n d efficiency of their use. N e w kinds of products will be developed, a n d the average nutrient content of the materials a n d mixtures will rise to even higher levels. F u r t h e r improvement will be m a d e in the physical condition of fertilizers a n d in the methods a n d means of distributing them in the field. Atomic and solar energy m a y eventually be applied in the manufacture of fertilizers, specifically in fixing atmospheric nitrogen. T h e near future holds no threat to t h e supremacy of synthetic ammonia as the basis for nitrogen fertilizers. For the United States at least, anhydrous ammonia, nitrogen solutions, a m m o n i u m nitrate, a n d urea will .continue to gain ground as the principal nitrogen materials. M o r e attention to less-soluble forms of nitrogen, such as urea-formaldehyde products, can be expected. T h e dominant position of normal superphosphate in the domestic phosphate industry will be threatened increasingly by triple superphosphate which might become the leading source of P2O5 within the next
5 years. Greater production of a m m o n i u m phosphates and calcium metaphosphate is expected, but the immediate prospect for increased use of nitric acid in the domestic processing of phosphate rock appears to be small. Phosphoric acid will gain in the fertilizer industry, a n d elemental phosphorus will serve increasingly for fertilizer manufacture. Potassium chloride is unlikely to suffer serious competition from other potash carriers in the foreseeable future. T h e r e is still room for great progress in the manufacture of granular mixed fertilizers, a n d the potentialities of liquid mixtures are just being realized. Wider adoption of soil-testing practices and evermounting transportation costs could shift mixed-fertilizer production from large centralized plants to smaller local units. Agronomic research has played a vital part in shaping the destiny of the fertilizer industry throughout the latter's history. For the future, still greater emphasis should be placed on basic studies in plant nutrition a n d all of its interrelationships, so that, together with technological research, the industry m a y be guided even more intelligently in providing the nutrients in the most efficient and economical forms for specific crops u n d e r various conditions of soil, climate, and cultural practice. VOL. 50, NO. 5
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MAY 1958
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of W a r . Headed first by Arthur B. L a m b , then by Richard G. Tolman, Frederick G. Gottrell, and others, this laboratory investigated catalysts, preparation and purification of syn thesis gas, design of high-pressure equipment, and other phases of the process. Nitrogen Materials Fifty years ago, sodium nitrate, a m m o n i u m sulfate, and relatively small quantities of cyanamide and calcium nitrate—products containing less than 2 1 % nitrogen—accounted for nearly all of the world supply of chemical nitrogen fertilizers. T h e advent of synthetic ammonia paved the way, however, for remarkable changes. Today, the fertilizer nitro gen used in the United States origi nates mostly as ammonium nitrate (33.5% N ) , urea ( 4 5 % N), and such liquid products as anhydrous ammonia ( 8 2 % N) and aqueous solutions of ammonia with ammo nium nitrate or urea (35 to 5 0 % N). Initiated around 1930, the use of anhydrous ammonia and the aque ous solutions in the domestic manu facture of mixed fertilizers has so increased that the greater portion of the nitrogen in such fertilizers is now derived from these materials. Another important accomplish ment, developed chiefly since World W a r I I , was the perfection of tech niques and equipment for adding an hydrous ammonia to irrigation water and for injecting it into' the soil, thus enabling the farmer to use directiy the cheapest and most con centrated form of nitrogen; little practiced in other countries as yet, such consumption of nitrogen in the United States was nearly 400,000 tons in 1957. Investigations in C a n a d a and the United States during World W a r I I led to production of nearly pure am monium nitrate in the form of gran ules suitable for fertilizer use, with the result that about 1,000,000 tons of such material are now consumed annually in the United States alone. Manufacture of urea in the United States, previously limited to one plant, has increased tremendously in the last 10 years. T h e close of 1957 found nine facilities in opera tion and three under construction, with a total annual capacity near 725,000 tons. Although large quan tities of urea are used for industrial purposes and as a protein supplement
in animal feeds, most of these plants look to fertilizer outlets for the major portion of their production. Progress in Phosphates Marked changes in the phosphate industry have occurred in the past 50 years. Processes have been im proved greatly, new products have appeared, and elemental phosphorus has gained importance as a basic material for fertilizer manufacture. Although normal superphosphate, first made more than a century ago, still provides the greater portion ( 6 0 % in 1957) of the world supply of fertilizer phosphorus, its domi nance has been threatened pro gressively, particularly in the last decade, by more concentrated ma terials—such as triple superphos phate, ammonium phosphates, and calcium metaphosphate—as well as by the processing of phosphate rock with nitric acid and the direct use of phosphoric acid in the produc tion of mixed fertilizers. Domestic manufacture of triple superphosphate, the principal com petitor of normal superphosphate, was established on a permanent basis in 1907 with the opening of a small plant at Charleston, S. C. T h e total annual capacity for pro ducing triple superphosphate in creased gradually to 793,000 tons (nine plants) in 1951. By the end of 1957, however, the capacity had risen to 2,225,000 tons in 15 plants having coexisting facilities for mak ing phosphoric acid, and other plants produced the material with pur chased acid in normal superphos phate equipment. In 1957, triple superphosphate supplied 3 8 % of the domestic output of phosphorus in the form of superphosphate, as compared with only 1 1 % in 1948. Progress in the domestic produc tion of fertilizer-grade ammonium phosphates, initiated on a large scale in 1917, includes the recently introduced manufacture of diammonium phosphate with both by product and synthetic ammonia. This development was , the first major departure from ammonium sulfate as a fertilizer outlet for by product ammonia. T h o u g h still confined to a relatively small tonnage, manufacture of calcium metaphosphate, developed by the Tennessee Valley Authority during the last 20 years, is especially' signifi cant because it marks the first de
parture from the orthophosphates in the history of the chemical fer tilizer industry. Before 1930, virtually all of the phosphoric acid used in fertilizer manufacture was m a d e by the sul furic acid process. I n recent years, however, increasing quantities of acid made from electric-furnace phos phorus have been used. In 1955, for example, the domestic use of fertilizer phosphoric acid totaled 689,000 tons of P2O6, of which 9.8% was produced from phosphorus. First applied com mercially by R e a d m a n in England about 1890, the electric furnace process has found its greatest de velopment in the United States where, as in other countries, it still is operated chiefly in the interest of high-purity products for nonfertilizer purposes. Still in operation, the first electricfurnace plant for phosphorus in the United States was opened in 1897 at Niagara Falls, Ν . Υ., with the chief initial purpose of supplying the m a t c h trade. From this beginning, the domestic industry, now comprises 12 plants which produced 339,000 tons of phosphorus in 1957. Among the accomplishments contributing to this progress was the pioneering work (1915-16) of Ross, Carothers, and Merz, in applying the Cottrell precipitator to the recovery of concentrated phosphoric acid from phosphorus-oxidation gases—the first use of the precipitator for recovery of the primary product of a process. First done commercially in 1920 at Anniston, Ala., use of the Cottrell precipitator has continued to be a key operation in the manufacture of acid from phosphorus. Also, the work of Waggaman, Easterwood, and Turley led to commercial production. of phosphoric acid by the blast-furnace process at Nash ville, Tenn. (1929-40). Significant advances have been made in the mining of phosphate ores and their preparative treatment. Selective flotation in ore beneficiation is a good example. Phosphate flota tion was first done on a large scale in 1929 in Florida. Together with kin dred agglomeration methods, it now accounts for more than 5 0 % of that state's annual output (10,528,000 long tons in 1956) of phosphate rock. The Potash Problem Germany's half-century of nearly complete domination of the world VOL 50, NO. 5 ·
MAY 1958
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supply of potassium salts began to be threatened by France in 1910, but it was not until the opening of the New Mexico - deposits in 1931 that the way was paved for a do mestic industry which by 1941 was capable of supplying completely the nation's potash requirements. Perhaps the most significant of the more recent achievements in pot ash technology, flotation of soluble potassium ores was introduced on a large scale at Carlsbad, N . Mex., in 1935 in what is believed to have been the first commercial plant to concentrate a soluble salt by flota tion in a saturated brine. A technically successful process for extracting potash from sea water (averaging about 0.05% K 2 0 ) by means of a regenerable organic pre cipitant was developed recently in Europe. Although it has not been applied commercially because of the lower cost of potash from other sources, this research marks a step toward utilizing a resource which contains some 6 X 1014 tons of K2O. During the past 50 years, marked changes have occurred in the kinds and grades of potash salts used in the United States. Thus, in 1909, kainite and manure salts (12 to 2 0 % K 2 0 ) supplied the greater portion of the potash, and low-anal ysis potassium chloride furnished most of the remainder. In 1957, however, more than 8 0 % of the consumption was in the form of po
tassium chloride containing 6 0 % or more of K2O. Potash production has grown from 1000 short tons in 1915 to 2,200,000 tons in 1957. Other Nutrient Elements
Limestone and other materials applied as soil-neutralizing agents, rather than as fertilizers, have been the major sources of plant-nutrient calcium and magnesium in the United States for many years. Large quantities of calcium also reach the soil in superphosphates and raw phosphate rock. T h e magnesium in fertilizers is supplied chiefly by dolomitic limestone and sulfate of potash-magnesia. Sulfur in fertilizers has been de rived mostly from the sulfuric acid used in their manufacture. In 1957, for example, about 1,000,000 tons of sulfur were applied to United States soils in the form of normal superphosphate and am monium sulfate. Thus, the industry's concern with sulfur has been chiefly over supplies of raw materials for producing its sulfuric acid require ments, a matter which has presented no great difficulties in this country since mining of salt-dome sulfur by the Frasch process was started in Louisiana more than 50 years ago. A notable development in the last 10 years has been the increase in production of elemental sulfur from natural and refinery gases. In 1909, there was no fertilizer
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Granulated fertilizer resists caking in bags 42 A
INDUSTRIAL AND ENGINEERING CHEMISTRY
trade in the so-called trace ele ments, but their importance was recognized by the work of H. Agulhon, G. Bertrand, W. E. Brenchley, M . Javillier, J. A. Voelcker, and others. Molybdenum is one of the latest additions to the list of ac cepted trace elements, among which iron, boron, copper, manganese, and zinc have received the most atten tion. Aside from their incidental occurrences in fertilizers, plant-nu trient applications of the last four elements in the United States, for example, probably totaled more than 13,000 tons in 1957. Although water-soluble salts are the chief source of trace elements for fertilizers, increasing attention has been given recently to the use of glasses and other insoluble or slightly soluble carriers for improv ing the nutrient efficiency and de creasing the toxicity hazard of such elements. Also of growing interest are the organic chelating agents, which have the property of maintain ing copper, iron, manganese, and zinc in nonionized water-soluble forms, so that these elements may be absorbed readily by plants under a wide range of soil conditions.
Developments in Mixed Fertilizers
Fertilizer materials have been mixed and compounded to yield products containing various per centages and ratios of two or more plant nutrients since the earliest days of the industry. This practice has had its widest application in the United States where such prod ucts accounted for 6 8 % of the total use of Ν, P2O5, and K 2 0 as commercial fertilizer in 1957, a proportion not greatly different from that (59%) in 1909. Fifty years ago, manufacture of mixed fertilizers was still confined almost entirely to the dry-mixing of the individual materials by relatively simple methods involving no chem ical processing. Around 1930, how ever, revolutionary changes in the domestic industry were initiated by adding anhydrous ammonia, or its aqueous solutions with ammonium nitrate or urea, directly to mixed fertilizers containing superphosphate, thus permitting the use of large quantities of cheap nitrogen. Preceded by the pioneering inves tigations started in the 1920's by Ross, Hardesty, and their associates,
one most important change has been the great progress, since 1940, in the manufacture of granulated mixtures. Requiring special processes and equipment, this development is rapidly gaining major status. T h e manufacture and use of liquid mixed fertilizers and fertilizer-pes ticide mixtures has developed mostly since 1950. Compared with solid products, liquid mixtures appear to have the advantage of lower capital investment and labor costs, and the problems of physical con dition and uniformity of composi tion are less difficult. Before 1925, the average concen tration of the three principal plant nutrients in mixed fertilizers had been about 1 4 % for at least 45 years. Subsequentiy, the average has increased steadily, especially since World W a r I I , to 2 9 . 5 % in 1957. This change has made pos sible huge savings in manufacturing, handling, transportation, and ap plication costs per unit of nutrients, an economy which is reflected in the fact that relative to costs in 1910-14 the index number of the price paid for fertilizer by the American farmer during the last decade has averaged only about 6 0 % of the index for all commodities bought for use in farm production. While this progress in volved the efforts of people in, many fields, much credit must be given to the research of the chemist and the agronomist, not the least of which were the extensive studies of the properties of concentrated fer tilizer materials and their behavior in mixtures conducted in the U. S. Department of Agriculture under W. H. Ross (1915-45)'. Looking A h e a d
As the world will become in creasingly dependent on commercial fertilizers to provide the food re quirement of its expanding popula tion, the outlook for the fertilizer industry appears to be promising, indeed. Each nutrient element per forms specific functions in the growth and fruiting of plants, which brook no substitutes. Thus, unlike so many other manufactured commodi ties, the essence of fertilizers is not subject to change, though its forms may differ greatly. T h e poten tiality for the domestic industry is in dicated by the fact that the current average use of the three principal plant nutrients in Western Europe
Nitrogen-rich ammonia is applied toι growing crops by injection into the soil
totals about 49 pounds per acre of agricultural land (including land under tree crops and permanent meadows and pastures), as compared with only 11.5 pounds in the United States. T h e years ahead will see important advances in the technology of fer tilizers and in the economy and efficiency of their use. New kinds of products will be developed,· and the average nutrient content of the materials and mixtures will rise to even higher levels. Further im provement will be made in the physical condition of fertilizers and in the methods and means of dis tributing them in the field. Atomic and solar energy may eventually be applied in the manufacture of ferti lizers, specifically in fixing atmos pheric nitrogen. T h e near future holds no threat to the supremacy of synthetic am monia as the basis for nitrogen fer tilizers. For the United States at least, anhydrous ammonia, nitrogen solutions, ammonium nitrate, and urea will .continue to gain ground as the principal nitrogen materials. More attention to less-soluble forms of nitrogen, such as urea-formaldehyde products, can be expected. T h e dominant position of normal superphosphate in the domestic phos phate industry will be threatened increasingly by triple superphos phate which might become the lead ing source of P2O5 within the next
5 years. Greater production of ammonium phosphates and calcium metaphosphate is expected, but the immediate prospect for increased use of nitric acid in the domestic process ing of phosphate rock appears to be small. Phosphoric acid will gain in the fertilizer industry, and ele mental phosphorus will serve in creasingly for fertilizer manufacture. Potassium chloride is unlikely to suffer serious competition from other potash carriers in the fore seeable future. There is still room for great progress in the manufacture of gran ular mixed fertilizers, and the po tentialities of liquid mixtures are just being realized. Wider adop tion of soil-testing practices and evermounting transportation costs could shift mixed-fertilizer production from large centralized plants to smaller local units. Agronomic research has played a vital part in shaping the destiny of the fertilizer industry throughout the latter's history. For the future, still greater emphasis should be placed on basic studies in plant nutrition and all of its interrelation ships, so that, together with tech nological research, the industry may be guided even more intelli gently in providing the nutrients in the most efficient and economical forms for specific crops under vari ous conditions of soil, climate, and cultural practice. VOL 50, NO. 5
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MAY 1958
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