Postwar Fertilizer Explodes
During the 1940s, fertilizer exploded in more ways than one. During the war, nitrogen was one of the prime components of TNT and other high explosives, and the U.S. government built 10 new plants to supply nitrogen for bombs. After the war, those plants produced ammonia for fertilizer. Fertilizer use exploded, in part because the supply was there and in part because farmers and scientists understood how important nutrients were to crops.
Modern science tells us that growing plants need at least 16 nutrients to be healthy.
- Primary nutrients are nitrogen, phosphorus and potassium, known by the chemical symbols of N, P and K.
- Secondary nutrients are calcium, magnesium and sulfur.
- Micronutrients include boron, chlorine, copper, iron, manganese, molybdenum and zinc.
- Other nutrients that are easily available in the environment include carbon, hydrogen and oxygen. These last three do not need to be supplied by fertilizers.
Farmers have known for centuries that soil doesn’t necessarily contain all of the nutrients that plants need. The ancient Greeks and Romans knew that manure spread on fields helped crop production immensely. Arab civilizations collected the written knowledge about farming. Somewhere along the line, farmers realized that ground up bones provided nutrients. By 1815, England was importing so many bones for bone meal that people on the Continent starting complaining:
“England is robbing all other countries of their fertility. Already in her eagerness for bones, she has turned up the battlefields of Leipsic, and Waterloo, and of Crimea; already from the catacombs of Sicily she has carried away skeletons of many successive generations. Annually she removes from the shores of other countries to her own the manorial equivalent of three million and a half of men… Like a vampire she hangs from the neck of Europe.”
Bird droppings, known by the Spanish name guano, became popular fertilizers in the U.S. in the 1800s. The effectiveness of all of these early fertilizers was tested by trial and error experiments by farmers and later scientists.
It was not until the last two centuries that chemists began to understand which specific chemical elements were supplied by materials like guano and bone meal. By the 1940s, plant scientists at land grant colleges and research facilities at the Tennessee Valley Authority (TVA) had the list of 16 essential ingredients for plant growth. The only problem was figuring out how to produce enough nitrogen, phosphorus and potassium. The three primary nutrients were needed in quantities approaching the millions of tons by 1940.
In the early part of the 20th Century, potassium was mined from potash deposits, and the largest were in Germany. As World War I approached, U.S. officials began the systematic “Great Potash Search of 1910-1914.” For a time, the brine encrusted lakes in the Nebraska Sand Hills became a major source of potash for America. That industry collapsed after the war when Germany started exporting again. By 1940, new sources had been discovered in Canada, and there were chemical processes coming on line to supply potassium.
By 1940, phosphorus was also being produced by chemical processes and by mining phosphate rock. In the 1940s, the use of “normal superphosphate” fertilizers peaked. In later decades, it was replaced by triple superphosphate and ammonium phosphates.
Nitrogen production got the biggest boost from World War II developments. Nitrogen is, of course, one of the main ingredients in explosives. During the 1930s, the U.S. government spent millions of dollars researching how to produce nitrogen from the air we breathe. That process requires a lot of electricity, so some of the first plants were built near hydroelectric dams in the TVA. The nitrogen produced took the chemical form of ammonia.
When World War II started, the government constructed 10 new plants to produce ammonia for munitions. All were located in the interior of the country. Several of the plants were built alongside natural gas pipelines so they could use the gas as raw material for their production. By the end of the war, these new plants and the old ones were producing 730,000 tons of ammonia each year, and had the capacity of producing 1.6 million tons.
When the nitrogen was no longer needed for bombs, what were they going to do with all this capacity? The answer was, use the nitrogen-rich ammonia for fertilizing the nation’s crops.
Stan Jensen says nitrogen fertilizer production “really took off” after the war. “Nitrogen fertilizer was a huge factor in the yield increases that began [then].”
As more and more farmers were planting most of their farms in one or two major cash crops, fewer and fewer were rotating their crops. They had to artificially build back the nitrogen that corn, wheat, soybeans or cotton pulled out. The source was there, but there was some work still to do on how to apply ammonia to the fields.
During the 1940s, most of the ammonia was applied as solid ammonium nitrate pellets. But this form is highly explosive. In fact, ammonium nitrate mixed with fuel oil is a common explosive still used in mines. There were several disasters where the material exploded in ships or other transports.
By the mid 40s, researchers were exploring ways to apply anhydrous ammonia directly into the soil. It won’t explode, but it has to be kept under pressure and usually refrigerated. It can “burn” skin by drying it severely, and it can crowd out oxygen in a closed area and even cause death by asphyxiation. But, anhydrous ammonia has the highest nutrient content of any fertilizer. It’s 82.5 percent nitrogen.
So, in 1943, researchers at the Mississippi Agricultural Experiment Station came up with a way of injecting anhydrous into the soil. They used a knife-like applicator with an iron pipe welded on the back of it to inject the material five or six inches below the soil. Then adisc hiller followed immediately behind to cover the channel and trap the anhydrous in the soil. This method of ammonia application overtook the pellets by 1960 and still predominates in the Great Plains today.
John Steingard (left) says that some farmers used too much fertilizer when anhydrous ammonia first came out. “We just put on a lot of it because the more we put on the better the crop, it seemed like. Now, its more controlled.”
Holly Miller (right) saw the explosion of fertilizer use first hand. After the war, Holly opened a seed business in York, and he believed in educating farmers about the new technologies. “I had meetings all the time, every year,” he says. “Of course, education is excellent. My theory of education is no better than the application of it.”
By 1950, the annual capacity for ammonia production had shot up from 1.6 million tons in 1946 to 2.6 million tons. Artificial fertilizers combined with new hybrid crops, new pesticides and developments in irrigation to produce an explosion in crop yields and production.
Written by Bill Ganzel and Claudia Reinhardt, the Ganzel Group.