 Why do we use fertilizers in agriculture? Evidence suggests that farmers were using manure to fertilize their crops as long as 8,000 years ago. But it wasn't until the 19th century that scientists pinpointed the key nutrients that plants need to grow – nitrogen, phosphorus, and potassium – and began to develop methods for manufacturing them commercially. At the start of the 1900s, a key development was the Haber-Bosch process – a method to produce ammonia at scale from molecular nitrogen and hydrogen gas, which can then be used as a nitrogen fertilizer. Since then, our use of fertilizers has increased year on year, from 52 million tons in 1961 to 215 million tons in 2019. It is estimated that synthetic nitrogen fertilizers support nearly half of the world's population. The widespread use of these fertilizers, however, is largely to blame for the increase in the amount of man-made nitrogen compounds in the air, water, and soil – which have doubled over the past 100 years. While they remain a controversial topic, fertilizers are an essential tool for modern farmers who use them to achieve high crop yields and replenish the soil nutrients lost from cultivation. This enables economies of scale that help to keep both farmers in business and food prices low for consumers. There are also environmental benefits. Higher crop yields mean we need to use less land for farming, allowing natural habitats to be protected. But there are a range of environmental issues, too. Not all of the nutrients from fertilizers are used by the plant or retained in the ground. The rest runs off or leeches from the soils and into the surrounding habitats, leading to biodiversity loss and eutrophication of waterways and the development of toxic blue-green algae. Nitrogen pollution also contributes to smog, acid rain, forest dieback, coastal dead zones, and stratospheric ozone depletion. The unpredictable cost of fertilizers is also an issue for producers, as its cost is dictated by the availability of minerals and natural gas. Key raw materials needed to produce synthetic fertilizers. Global natural gas prices recently hit a 14-year peak and with Russia cutting its exports of fertilizers, this has led to a huge increase in the cost of fertilizers globally, driving up the cost of producing our food enormously. With potassium and phosphorus also being limited resources, fertilizer quality and cost will be big concerns for producers in the future. But could we live without fertilizers? In Sri Lanka, synthetic fertilizers were banned without a plan to manage the after-effects. Farmers saw their yields collapse, triggering social unrest and contributing to a national economic crisis. So a cold Turkey situation simply isn't an option, as fertilizers remain an important tool in modern farming. Fertilizer and precision application of fertilizers using modern technology to increase crop yields and return nutrients to the soil, while limiting environmental runoff is a good start. Circular agriculture uses organic fertilizer sources such as manure, food waste and even human sewage waste. This can help reduce the pollution and impacts associated with fertilizer use and production. Urine, for example, is rich in phosphorus and could provide half of the phosphorus necessary to grow cereal crops. The types of crops grown can also lead to lower fertilizer use. Lagoons like beans, peas and lentils have the ability to capture nitrogen in the atmosphere and fix it into the soil. Growing more lagoon crops and green manures as part of a crop rotation or alongside other crops is one of the best ways that we can replenish nitrogen in the soil. Subscribe to Food Enfolded to learn more about the origins and sustainability of your food.