50% of the nitrogen in our bodies came from the Haber–Bosch process. It’s in every protein and every strand of DNA. Ponder that — “half of the nitrogen in your blood, your skin and hair, your proteins and DNA, is synthetic.”I just finished Hager’s Alchemy of Air, the story of “the most important discovery ever made. See if you can think of another that ranks with it in terms of life-and-death importance for the largest number of people. Put simply, this discovery is keeping alive half the people on earth.”The Haber-Bosch process catalyzes the production of ammonia (NH3) from N2 and H2 gas. We need “fixed nitrogen”, available to our organic chemistries as atomic nitrogen. It is the limiting factor for the growth of all food. While nitrogen gas is about 80% of our atmosphere, not one atom of it is available for our use when tightly bound by the triple bond of N2 gas, the strongest chemical bond in nature. It is sequestered all around us. In nature, N2 is liberated to atomic nitrogen in small amounts by lightning strikes (it needs 1000°C) and slowly by nitrogen-fixing bacteria in the soil. Hager argues that if we reverted to relying on just those natural sources, three billion people would die of starvation in short order — our soils simply could not produce enough food for the mouths now on Earth.Historically, fixed nitrogen came from manure and compost, the first supply to be used up. Once local bat caves were depleted, the world looked for new sources. In 1850, the Chinchas Islands off the coast of Pisco, Peru became the most valuable real estate on Earth. They were covered by centuries of bird guano, excavated by slave labor in a hellish scene. Guano became 75% of the GDP of Peru by 1859. But the world wanted more. In 1856, the U.S. passed the Guano Islands Act, whereby anyone could annex a guano island they found anywhere in the world and make it a U.S. territory. Then the Guano War of 1863 broke out between Spain and Peru and Chile. Darwin had discovered peculiar nitrate deposits in high Atacama Desert of Chile. And by 1900, Chile was supplying 2/3 of all fertilizer on Earth. The Chilean harbor was the location of the first major sea battle of World War I, between France and Germany. The nitrate supply was essential to war-making. “They later called World War I the chemist’s war.” As we saw in the massive explosion recently in Lebanon, fixed nitrogen can also be used to make explosives or provide the “N” in TNT or nitroglycerine.As a latecomer to the nationhood, Germany did not have colonies to exploit for food or fuel, and their shipping lanes were vulnerable to foreclosure by the British navy. Germany’s chemical companies undertook a major effort to pull fixed nitrogen from the air, to support local food production and the munitions of war. “BASF’s nitrogen project grew into the biggest scientific effort in history, comparable in scale to the Manhattan Project in WWII.” The goal was to find a catalyst that could assist with the required chemistries by reducing the temperature and pressure required to something that could be economically feasible in an industrial plant. After 20,000 experiments, running through the periodic table, they discovered osmium could do the trick, and BASF cornered the market for this rare element, but even that would not be enough for the volumes needed. Then they found uranium, and finally, a more reasonable iron-aluminum-calcium combination. The factories required staggeringly huge pressure vessels, like had never seen before.We use the same catalysts today, in a codependency with the petrochemical economy of byproducts and waste heat. The Haber process consumes 4% of the world's natural-gas production and 1.5% of the world's energy supply.Half of the nitrogen in fertilizer is taken up by plants, much of the rest washes out. Fertilizer runoff from the Mississippi river has doubled nitrates in the the Gulf of Mexico, making it look like chocolate milk with an enormous Dead Zone. In Europe, the annual 1.5b tons of nitrogen fertilizer runoff from the Rhine has made the Baltic Sea one of the most polluted marine systems on Earth.Even our atmosphere has become a “huge fertilizer silo, with tons of growth-promoting fertilizers showering from the sky. The amount of fixed nitrogen filtering down to earth in some places has risen so high that it equals the amount American farmers typically apply to their spring wheat.” Nitrogen oxides also create acid rain.We have become dependent on fertilizer. To recap, “while the population nearly quadrupled during the twentieth century, food production — thanks first to Haber-Bosch, second to improved genetic strains of rice and wheat — increased more than sevenfold. That is the simple math behind today’s era of plenty.”