To feed ever-increasing populations, botanists and other scientists have long worked to understand how plants grow and how their yields might be increased. Understanding the role of nitrogen in particular was key to producing enough food to meet the nutritional needs of the global population. In the 18th century, scientists discovered nitrogen. They understood that it played an important part in sustaining life, but they could not understand how. Experiments with several types of fertilizers revealed that an unknown chemical process helped transform nitrogen in the atmosphere into something that could help plants thrive. In the 19th century, scientists determined that microbes in the soil interacted with the roots of legumes to help capture (or “fix”) nitrogen. For centuries, farmers understood that growing crops like lentils, peas, and beans helped soil, but they did not understand the science behind it. Guano from South America proved rich in nitrogen, so it was shipped to Britain to fertilize fields; however, there was a limited supply. Scientists needed to find a way to manufacture fertilizer synthetically.

The discovery of ammonia in 1909 paved the way for the use of fertilizers that would alleviate the need for rotating crops. The green revolution followed, contributing to the population boom; in the 20th century, the human population swelled from 1.