Fertilizers, Then and Now - Journal of Chemical Education (ACS

Chemical Education Today

Fertilizers, Then and Now by Kathryn R. Williams

Agriculture and the teaching of agricultural chemistry have been popular JCE topics, especially in the Journal's early years. The first of these, a 1924 committee report (1) from the Division of Chemical Education, argued that general chemistry courses have largely ignored agricultural applications: “[T]he agricultural student should have chemistry where the illustrations are drawn from the great fields of agriculture and biology.” In succeeding years, JCE subscribers frequently encountered additional articles on the education of agricultural students (2-11). Agricultural chemistry was also one of the topics for the annual Prize Essay Contest for high school students (12), and winning entries appeared in JCE until the program's demise in 1931. Other examples of agriculturally focused papers include two contributions to The Chemist at Work series (13) describing research activities in a soils laboratory (14) and in an agricultural experiment station (15). A recurring theme in these articles is the importance of fertilizers and the chemist's role in their development. For example, H. A. Halvorson of the Minnesota State Department of Agriculture (7) said, “I have often thought that of all of the pursuits related to agriculture, the manufacture of fertilizers is the one that comes nearest to the classification of a chemical industry.” And Charles H. Hunt of the Ohio Agricultural Experiment Station (15) wrote, [T ]he quality of plants and indirectly...the food eaten depends upon the soil and the climate. The climate cannot be regulated but, to a partial extent, the deficiency of the soil can be overcome.

In recognition of the American Chemical Society's 2010 Chemists Celebrate Earth Day's emphasis on plants and soil, this installment of From Past Issues focuses on articles from the Journal of Chemical Education specifically related to fertilizers. Potassium Of the big three (N, P, and K), potassium, as potash (the common name for K2CO3, but often used generically for potassium compounds), was the first to be produced industrially in the United States from wood ashes, but not for use as fertilizer. In his 1926 article (16), U.S. Bureau of Chemistry Chief C. A. Browne told the story of potash production in the colonial and early national era. Most of the product was sold in Europe to support manufacture of cloth, glass, soap, and other commodities. The U.S. potash industry declined in the early 1800s, prior to recognition of its importance in soil fertility, because of depleting timber supplies and the development of the LeBlanc soda process in Europe. According to Browne (16), From an agricultural point of view the manufacture of potash from wood ashes constituted one of the greatest economic crimes in the history of the United States... The agricultural development of the Eastern United States has suffered greatly from the consequences of this error.

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Figure 1. Photograph of an American Potash and Chemical Corporation plant at Searles Lake, California. View northwest from surface of salt body (foreground), with Argus Range in background. Image originally from J. Chem. Educ. 1930, 7, 741.

Articles published in 1927 and 1930 (17, 18) examined the role of potassium compounds from a contemporary viewpoint, namely, the need for domestic supplies. According to R. Norris Shreve (17), The certain condition for increasing the productivity of our soils...will depend upon supplying potash and other fertilizers bountifully, even extravagantly, to the soils of this country.

At that time, most usable potassium salts were obtained from mines in Alsace (France) and Strassfurt (Germany) “under conditions which practically constitute monopolistic control of the potash market” (18). There were also U.S. operations, primarily in California (Figure 1) and in Maryland, and George R. Mansfield of the U.S. Geological Survey described other known domestic sources (18). Both Shreve and Mansfield emphasized the need to develop more U.S. supplies. Shreve concluded his paper by saying (17), We have plenty of potash resources. Can we commercialize them so as to supply a large part of our potash demands? The answer lies with the American chemist backed by the American engineer and far-sighted American men of business.

Phosphorus In 1933, William H. Waggaman, formerly of the U.S. Department of Agriculture, wrote a two-part series, “Phosphate Rock Industry of the United States” (19). Having abundant sources of phosphate rock in several southeastern states, as well as deposits in parts of the Northwest, the United States was at an advantage compared to many other countries. Although the U.S. was once the chief supplier to Europe, by the 1930s deposits in North Africa accounted for most exportation, and Soviet Russia was also becoming a supplier. Waggaman did not find this loss of output to be detrimental, and he expressed sentiments similar to those of Shreve (19): It is to the interest of American agriculture to conserve our supplies of this important mineral...it is not greatly to be regretted that the Old World is no longer dependent on this country for its supplies.

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r 2010 American Chemical Society and Division of Chemical Education, Inc. pubs.acs.org/jchemeduc Vol. 87 No. 2 February 2010 10.1021/ed8000683 Published on Web 01/12/2010

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Figure 2. Dragline removing upper soil layers [overburden in swampy ground] for phosphate mining in a wetlands area near Lakeland, Florida. This dragline has a 165-foot boom, and uses a six-cubic-yard bucket. Total weight of machine is 820,000 pounds. Image originally from J. Chem. Educ. 1933, 10, 478, bottom of page.

In part I of his series, Waggaman described the various U.S. deposits, especially those in Florida, where he lived at the time. Part II outlines methods of mining and preparing phosphate for marketing, primarily as superphosphate, Ca(H2PO4)2 3 H2O, obtained by reaction of sulfuric acid with phosphate rock. Waggaman proudly included a number of photographs of mining activities near Lakeland, FL. Like most of the authors mentioned in this look into the past, Waggaman did not express any concern for the environmental harm caused by mining operations as shown, for example, in Figure 2. Although such destruction can never be fully reversed, Florida now requires land reclamation from these activities (20). Nitrogen In the 1920s, articles by J. G. Lipman (21) and F. E. Allison (22) emphasized the importance of nitrogen in agricultural productivity. Lipman presented detailed arguments, primarily economic, in favor of more intensive methods of soil treatment to increase yields. He foresaw wide-ranging benefits (21): [W ]ith the aid of nitrogenous and other fertilizers, we shall increase the average acre yields, diversify our farming, restore our forests, approach a solution of the problem of agricultural surpluses, and, in general, bring to our agricultural population more efficient production, greater net returns, higher standards of living and a degree of stability and contentment that should be reflected in our national well-being and progress.

Allison also made statements in favor of increased per-acre productivity, but he tempered his arguments with a call for a “permanent agriculture” (i.e., sustainability, in 21st-century terms), including return of crop residues and manures to the soil; increased leguminous and cover plantings; and addition of lime to stimulate nitrogen-fixing soil bacteria. With nitrogen fertilizers, a doubled-edged sword always enters the picture, because of the obvious association with munitions and explosives, the subject of Michael Liang's article “Beware;Fertilizer Can EXPLODE” (23). Media coverage has made the public aware of the use of fertilizer components for terrorist activities (24), and these compounds are listed by the Department of Homeland Security as Chemicals of Interest (25). From an explosives point of view, the key compound is ammonium nitrate, which was the subject of a Domestic 136


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Commerce report by C. Kenneth Horner in October 1945, reprinted in the December 1945 issue of this Journal (26). Until 1939, the predominant U.S. market for NH4NO3 was for explosives because it was safer to handle than other choices. The fertilizer market did not become important in this country until the mid-1930s, although Europeans began using the compound soon after World War I. With the start of World War II, the need for NH4NO3 and other nitrogen compounds intensified, leading to the construction of numerous ammonia plants. By 1943, this actually led to a surplus of ammonia and ammonium nitrate, which was distributed to farmers. Although the NH4NO3 was initially unsatisfactory due to caking problems, research led by the Department of Agriculture overcame this problem. As the war drew to a close, the fate of government-owned ammonia plants was still undecided, but Horner foresaw continued use of NH4NO3 in agriculture (26): The economics in production and transportation are apparent. The ammonium nitrate proper is manufactured from synthetic ammonia without additional raw materials, and the plant food value is enhanced by having the nitrogen partly in the ammonia or reduced form and partly in the nitrate or oxidized form.

Concentrated Fertilizer Mixtures Horner's remarks about the benefit of having multiple forms of plant food in a single product reflect the increased use of fertilizer mixtures, or the so-called complete mixed fertilizers. A. B. Beaumont of the Massachusetts Agricultural College provided a short historical background of mixed fertilizers (27), which became popular in the U.S. following the research of Horace Stockbridge in the 1860s and 1870s. Fertilizer mixtures were commonplace by the time the Journal of Chemical Education debuted in 1924. J. W. Turrentine of the U.S. Bureau of Chemistry and Soils was a major proponent of the use of highly concentrated formulations. In his 1929 article (28), he extolled the use of synthetic ammonia in fertilizer production (in, for example, the synthesis of ammonium phosphates and nitrate). The following year, he wrote “Problems in the Fertilizer Industry,” the eighth segment of a multiauthor series, “Chemical Progress in the South” (29). At issue was the cost of packaging and shipping low-grade and single-function fertilizers. For example, NaNO3 contains only 16% (w/w) N, while KNO3 provides 37% (w/w) K and 14% (w/w) N. Considering the difficulty of large-scale manufacture of a compound containing all of the big three (e.g., potassium ammonium phosphate), several compounds were mixed and bagged together: (NH4)2HPO4 and KCl, or NH4NO3 and Ca(H2PO4)2 3 H2O. The introduction of high-grade mixed fertilizers led to a list of questions and research opportunities. According to Beaumont (27), High-analysis fertilizers have brought problems for the chemist and agronomist which are not unlike many of the problems that arise with the low-analysis materials. We shall have to go through some of the stages of testing and experimenting that were passed through 50 to 60 years ago.

Among the concerns Beaumont noted: roles and optimum concentrations of secondary and micronutrients, fertilizer application methods, tolerance of crops to highly concentrated NPK mixtures, physical properties (e.g., hygroscopicity and cakiness), the effects of continued use of fertilizers on soil quality, and the challenge of developing entirely new fertilizer materials.

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or dumpster, think about putting your waste to work. Search online using the term “compost” and discover how to build successful compost piles or where to buy an indoor countertop unit. Literature Cited

Figure 3. Structure of fulvic acid. Image originally from Figure 2 of J. Chem. Educ. 1977, 54, 600.

Compost As a member of an organic gardening cooperative, I have particular interest in reclaiming nutrients from plant residues, kitchen garbage, and animal wastes;in short, composting. The chemical and physical (and to lesser extent, microbiological) properties of humus, which includes decomposing materials and their products at various stages in the decomposition process, have been the subject of four articles in this Journal over the Journal's history. In his 1935 article (30), Selman A. Waksman of the New Jersey Agricultural Experiment Station summarized much of the data available at the time. At the outset, Waksman was careful to tell readers (30), In spite of a century and a half of progress in the study of humus, considerable confusion still exists today in regard to this group of ill-defined complexes, which play such an important role in soil fertility by serving as a reservoir of plant nutrients, and which represent the greatest storehouse of available energy on this planet.

Knowledge of humus was complicated by inconsistent chemical treatment of samples and the prevailing notion that humus was a simple chemical substance formed by processes distinct from natural decomposition. The topic of humic acid and its water-soluble partner, fulvic acid, was revisited in 1963 and in 1977 by Cornelius Steelink of the University of Arizona (31, 32). Like Waksman, Steelink acknowledged the lack of scientific investigations (especially in the United States), but his articles contain a number of chemical structures (e.g., fulvic acid, Figure 3) and proposed reactions. A recent paper by Davies, Ghabbour, and Steelink (33) describes important characteristics of humic substances (HSs): Solid HSs act as pH buffers, metal binders, solute sorbents, and redox catalysts, and they are photosensitizers. No other natural materials have so many functions in so many different places.

The authors also discuss practical usages (33): Humic acids derived from natural sources are cross-linked with polymers to make them insoluble in water. These products are then able to detoxify soils and surface waters contaminated with toxic organic and inorganic chemicals.

Commercial applications notwithstanding, the organic gardener's principal interest in humic substances is as replacements for fertilizers associated with mining operations and industrial syntheses. So, the next time you are feeding your garbage disposal


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1. Gortner, R. A.; Read, J. W.; Kraybill, H. R. The Teaching of Agricultural Chemistry. J. Chem. Educ. 1924, 1, 177–181. 2. Kraybill, H. R. The Place of Analytical Chemistry in Agriculture. J. Chem. Educ. 1925, 2, 120–127. 3. Browne, C. A. A Practical Course in Agricultural Chemistry for Elementary Students. J. Chem. Educ. 1925, 2, 240–248. 4. Headden, W. P. Broadening Agricultural Chemistry. J. Chem. Educ. 1926, 3, 201–212. 5. Knight, H. G. Training in Chemistry to Meet the Needs of the Present Agricultural Situation. J. Chem. Educ. 1929, 6, 886–893. 6. Osborn, R. A. First-Year College Chemistry and Students from the School of Agriculture. J. Chem. Educ. 1929, 6, 2189–2195. 7. Halvorson, H. A. Chemistry in the Service of Agriculture. J. Chem. Educ. 1938, 15, 578–584. 8. Webster, J. E. A Survey of Chemistry as Taught to Agricultural Students. J. Chem. Educ. 1930, 7, 849–855. 9. Friedenberg, E. Z. A Course in Inorganic Chemistry for Students of Agriculture. J. Chem. Educ. 1944, 21, 41–44. 10. Tanaka, J. A Topical Approach to Organic Chemistry for Agricultural Students. J. Chem. Educ. 1960, 37, 33–34. 11. Marshall, C. E. Chemistry for Students in Agriculture and Natural Resources. J. Chem. Educ. 1971, 48, 683–685. 12. Rice, R. E. The ACS Prize Essay Contest. J. Chem. Educ. 2005, 82, 1765–1766. 13. Williams, K. R. Faces From the Past. J. Chem. Educ. 2007, 84, 1587–1588. 14. Starkey, R. L. Research in a Soils Laboratory. J. Chem. Educ. 1938, 15, 427–430. 15. Hunt, C. H. Research in an Agricultural Experiment Station. J. Chem. Educ. 1938, 15, 281–283. 16. Browne, C. A. Historical Notes Upon the Domestic Potash Industry in Early Colonial and Later Times. J. Chem. Educ. 1926, 3, 749–756. 17. Shreve, R. N. Potash. J. Chem. Educ. 1927, 4, 230–241. 18. Mansfield, G. R. Potash in the United States. J. Chem. Educ. 1930, 7, 737–761. 19. Waggaman, W. H. Phosphate Rock Industry of the United States, Parts I & II. J. Chem. Educ. 1933, 10, 391-395; 476-483. 20. Mislevy, P.; Blue, W. G.; Strickler, J. A.; Cook, B. C.; Vice, M. J. Phosphate Mining and Reclamation. In Reclamation of Drastically Disturbed Lands I, Agronomy Monograph #41; American Society of Agronomy: Madison, WI, 2000; pp 961-1005. 21. Lipman, J. G. The Nitrogen Problem in Agriculture. J. Chem. Educ. 1927, 4, 845–860. 22. Allison, F. E. Nitrogen as a Plant Food. J. Chem. Educ. 1926, 3, 50– 58. 23. Laing, M. Beware;Fertilizer Can EXPLODE. J. Chem. Educ. 1993, 70, 392–394. 24. Department of Homeland Security. Brewing A Blast-less Fertilizer. ScienceDaily 4 September 2007, http://www.sciencedaily.com/ releases/2007/08/070829190807.htm (accessed Dec 2009). 25. Department of Homeland Security. DHS Chemicals of Interest. 6 CFR, Part 27, Appendix A. http://www.dhs.gov/files/programs/ gc_1185909570187.shtm (accessed Dec 2009).


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26. Horner, C. K. Ammonium Nitrate from War to Peace. J. Chem. Educ. 1945, 22, 611–612. 27. Beaumont, A. B. Concentrated Fertilizers: Problems for the Chemist and Agronomist. J. Chem. Educ. 1929, 6, 899–905. 28. Turrentine, J. W. Synthetic Ammonia in the Fertilizer Industry. J. Chem. Educ. 1929, 6, 894–898. 29. Turrentine, J. W. Problems in the Fertilizer Industry. J. Chem. Educ. 1930, 7, 2330–2335. 30. Waksman, S. A. Chemical Nature of Organic Matter or Humus in Soils, Peat Bogs, and Composts. J. Chem. Educ. 1935, 12, 511–519.

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31. Steelink, C. What Is Humic Acid? J. Chem. Educ. 1963, 40, 379– 384. 32. Steelink, C. Humates and Other Natural Organic Substances in the Aquatic Environment. J. Chem. Educ. 1977, 54, 599–603. 33. Davies, G.; Ghabbour, E. A.; Steelink, C. Humic Acids: Marvelous Products of Soil Chemistry. J. Chem. Educ. 2001, 78, 1609–1614.

Kathryn R. Williams is in the Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200; [email protected].


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Fertilizers, Then and Now - Journal of Chemical Education (ACS

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