Nitrate is any kind of compound that contains the inorganic nitrate ion (NO3—). Nitric acid (HNO3) is a nitrate. Most metals form nitrate salts when combined with nitric acid. In nature, there are relatively few nitrate minerals. Two important nitrates, potassium nitrate (KNO3) and ammonium nitrate (NH4NO3), are used as fertilizers to replenish nitrogen in the soil. Bacteria in the soil form nitrates from organic compounds containing nitrogen. Plants use these nitrates to make proteins. Nitrates can also form in the atmosphere. There, nitrogen oxide may combine with water to produce nitric acid, a part of the pollutant acid rain. Nitrates are also used in explosives, fireworks, and heart medicines. People take in nitrates daily, primarily from vegetables. But consuming large amounts of nitrates can help produce toxic substances in the body. See also Nitric acid; Nitrogen cycle.
