Looking Back on the Past 75 Years of in the United States
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Society Science Looking Back on the Past 75 Years of Soil Fertility in the United States t's hard to imagine what the of soil testing was a tool that was world would be like without the chosen to really make a difference in Iyield increases we've seen over many of these places. Simple 'do it the last several decades. A 50- or yourself soil test kits were the start- 60-year period where yields are flat ing point for this effort." seems unthinkable, yet this was The soil test kits used very simple the case in the latter half of the 19th chemistry that still exists. "We're century into the early 20th century currently working with a bunch of before agronomy organized itself as National Guard soldiers from Kan- a scientific discipline and soil-testing sas in Afghanistan, and we're using methods were developed. During this same technology," Mengel said. this year's Leo M. Walsh Soil Fertil- "And I've learned over the last six ity Distinguished Lecture at the months that Afghanistan has very November 2009 Annual Meetings high phosphorus levels because they in Pittsburgh, David Mengel, a pro- were tested with a LaMotte test kit." fessor of agronomy at Kansas State In 1914, Emil Truog, from University and an ASA-SSSA Fel- the University of Wisconsin, low, talked about the period around developed one of the first 1920 through World War II, which soil tests—a zinc sulfide he characterized as the "soil testing/ acidity test for farmers and problem solving era." county agents. "I grew up in the whole era of "It was a simple little test surpluses and concerns about how where you put soil in a little do we get rid of all this stuff we can crucible, added a liquid, produce, but that wasn't the case at boiled it, and with zinc sul- the turn of the 20th century," Mengel fide added, fumes came off said. "Erosion and nutrient depletion that turned a lead acetate pa- were really reducing both productiv- per black," Mengel explained. ity and productive acres in the U.S. "So it was sort of semi-quanti- The Great Depression, Dust Bowl, tative—the blacker it got, the and urbanization would all acceler- more lime you needed. But it ate that trend as we went on into the was a very important tool that was 1930s and 1940s, so the situation was used very widely." much different." In the 1920s and 1930s, Truog and Another thing that was differ- others, such as Roger Bray from the ent was the state of the science at University of Illinois, C.H. Spurway the time. ASA was first organized from Michigan State University, in 1907, and so the discipline of Michael Peech from Cornell, and agronomy was just getting started. M.F. Morgan from University Two years later, the concept of pH of Connecticut, developed field was first introduced. It would be test kit procedures to measure another 20 years until working pH pH, phosphorus, and potassium. meters and glass electrodes became "Most of the kits used either available and another 20 years after some sort of a pH by indicator that before flame photometers were dye, the Truog test, or a thiocya- widely used in the U.S. nate test to measure pH or acidi- ty," Mengel said. "Phosphorus was The Test Kit Years measured using various dilute ac- "By the early 1900s, agronomists ids, and ... potassium was measured and soil scientists were beginning to turbidimetrically by coboltinitrate look for ways to increase yields and application." restore productivity to what they Many states began equipping their county agents and specialists termed 'exhausted' soils," Mengel The top photo with some of these kits to do field- shows an early soil test said. "Soil testing addressed some of being used on a farm in 1942. Photo those important issues, particularly and farm-based soil testing, Mengel courtesy of Library of Congress Prints and said. Illinois promoted soil testing as Photographs Division, Washington, DC. The middle two acidity and phosphorus and potas- photos show the exterior and interior of a soil fertility train. a "do it yourself" project where its Photos courtesy of David Mengel. The bottom photo shows sium concentrations. The availability a Truog soil test kit. Photo courtesy of David Mengcl. March 2010V55N03 CSA News 5 county agents encouraged farmers anymore—these people do environ- At the end of World War II, there to bring samples in and then taught mental testing, feed sampling—a lot was a readily available supply of them how to do the tests themselves. of those sorts of things." fertilizer, particularly nitrogen, Hoeft Soil fertility trains soon began These days, large independent explained. The plants that were used traveling the Midwest testing soils labs are becoming the dominant for munitions during the war were for farmers. In addition to "soil doc- players in the soil-testing business now free to be used for something tors," the trains featured exhibits, as the number of state labs rapidly else, and at the same time, the U.S. labs, lectures, and even motion pic- decreases, Mengel said. One of the began using more petroleum. tures. They later evolved into lime downfalls of this is that it has been "Petroleum increased markedly, trains in Indiana and rock phosphate accompanied by a decline in soil- and as a result, so did refineries, and trains in Illinois in the 1930s and testing research. In Mengel's lab, the those refineries had a by-product of 1940s, transporting these materials most recently developed procedure hydrogen," Hoeft said. "And you throughout the state for farmers to they use is the Mehlich-3 phospho- ended up with the petroleum indus- load into their trucks. rus extraction, which was published try getting into the fertilizer market in the late 1970s. because they were using that hydro- Instrumentation and Labs Small labs also began to develop "A lot of our procedures are getting some seniority. Many during this time, particularly at uni- of them are plagued by issues of generation of hazardous versities but also at state agencies and even some businesses, Mengel waste. We need some more additional work going on!' said. Most continued to use soil test kit type technology until the "A lot of our procedures are get- gen in the Haber-Bosch process for mid-1930s. Advances in technology ting some seniority. Many of them ammonia production." in the late 1930s to 1940s led to the are plagued by issues of generation In the late 1950s and early 1960s, development of new, more precise of hazardous waste. We need some anhydrous ammonia was selling for instruments like pH meters and more additional work going on." less than $.05 per pound of nitrogen, glass electrodes, colorimeters, flame w-hJcTThad quite an impact-eojertil- photometers, and procedures like the The Fertilizer Era zefuse, according to Hoeft. lime requirement buffer test. There was plenty of soil fertili "I can remember farmers back Local county or company labs work going on after World War home saying, 'Well, if a little is gooc were common in the late 1930s according to Bob Hoeft, soil fertility a lot is better because as cheap as it is through the 1960s, and many still professor at the University of Uinois we can't get by without it.' The rate exist today. Some were operated by and an ASA-SSSA Fellow and for- were much, much higher than we'/e extension offices, USDA-SCS (now mer ASA president. Hoeft cov ered using today. I don't even want to, NRCS), or by fertilizer dealers or the "fertilizer era," the time roughly say what some of the rates were/-it other companies with farmer clients after the war through the late 1970s was about as much as they could get such as Campbell's Soup. During to early 1980s. He said fertilized sales through those applicators ana not the 1940s and 1950s, most land grant skyrocketed during this period. smoke themselves out of the field." universities established a central or "There were a state soil-testing lab, and in the 1950s number of things and 1960s, many state and regional that happened. i.S. Fertilizer U: co-ops and fertilizer manufacturing One was that by sales organizations established labs. the end of World "Testing volume exceeded 200,000 War II, science re- 14000 samples per year by the 1960s in ally took off a little many states," Mengel said. "Total bit more in terms testing in the U.S. peaked in the mid- of agriculture. We 1960s at about 3 million samples, had a number of -Nitrogen -Phosphorus but if you look at some of the more really talented in- Potassium recent information on soil sampling, dividuals working we're back to that [level] now. in the soil fertility "Private testing companies really area. And farmers started coming into play in the 1960s could easily see 19SO 1960 1970 1990 2000 2010 and 1970s.... Today, many of these the economic re- organizations play a really key role turn to the use of in a lot of states in providing testing fertilizers." Nitrogen, phosphorus, and potassium fertilizer use since services. And it's not just for soils 1950. Graph courtesy of Bob Hoeft. 6 CSA News V55 N03 March 20 Another reason for the increase in followed such as etridiazole (Dwell), fertilizer sales was the shift in agri- dicyandiamide, and ammonium culture from grain/livestock opera- thiosulfate. These products worked, tions to grain only, Hoeft noted. Hoeft said, but in some cases, they "We moved away from livestock still didn't solve the problems of fall operations, and when we did that, application of ammonia.