fred first's List: Nitrogen/Fertilizers

While a long list of variables drove this trend, from the increased use of pesticides to new varieties of corn, wheat, and rice, one of the most important factors was the introduction of synthetic fertilizer. Plants thrive on nutrients in the soil, and these mass-produced fertilizers led to the doubling of crop yields between 1950 and 1990. We learned how to feed ourselves because we learned how to feed plants.

While a long list of variables drove this trend, from the increased use of pesticides to new varieties of corn, wheat, and rice, one of the most important factors was the introduction of synthetic fertilizer. Plants thrive on nutrients in the soil, and these mass-produced fertilizers led to the doubling of crop yields between 1950 and 1990. We learned how to feed ourselves because we learned how to feed plants.

We learned how to feed ourselves because we learned how to feed plants.

For the first time in human history, the natural nitrogen content of soil (or the availability of nitrogen-rich manure) ceased to be a constraint on crop yields, and from Iowa to India, harvests rose steadily. This so-called Green Revolution, however, hasn’t proved to be particularly green in the modern sense of the word, since the application of synthetic fertilizers can have devastating environmental consequences, such as the dead zones off the Gulf Coast.

dead zones off the Gulf Coast. (Excessive amounts of nitrogen destroy the delicate equilibrium of the ocean, as they trigger toxic algal blooms that sap the sea of oxygen.) Furthermore, because the Haber process requires intense pressure and high heat, the production of fertilizer currently consumes more than 1 percent of the world’s energy supply and more than 5 percent of its natural gas. Paradoxically, just as climate change is threatening the global food harvest, our primary means of nourishing those crops only intensifies our use of fossil fuels.

the production of fertilizer currently consumes more than 1 percent of the world’s energy supply and more than 5 percent of its natural gas. Paradoxically, just as climate change is threatening the global food harvest, our primary means of nourishing those crops only intensifies our use of fossil fuels.

Fortunately, natural selection has already devised the perfect solution: a bacterial enzyme known as nitrogenase, which can fix nitrogen at room temperature using only a collection of metal ions, including the unusual molybdenum ion, and a hefty dose of energy-giving ATP. Found in the common dirt-dwelling microbe called Rhizobium, nitrogenase allows a long list of plants, from peanuts to lentils to clover, to fix nitrogen in the soil. (Interestingly, Rhizobia can’t fix nitrogen independently; they must first establish themselves in the root nodules of these plants — a classic case of symbiosis).

nitrogenase

For the first time in human history, the natural nitrogen content of soil (or the availability of nitrogen-rich manure) ceased to be a constraint on crop yields, and from Iowa to India, harvests rose steadily. This so-called Green Revolution, however, hasn’t proved to be particularly green in the modern sense of the word, since the application of synthetic fertilizers can have devastating environmental consequences, such as the dead zones off the Gulf Coast.