Ammonium (NH4+) is a positively charged ion comprised of four molecules of hydrogen and one molecule of nitrogen. Manure consists of potassium nitrate, ammonium, and methane. (VOY: "The 37's") In 2376, B'Elanna Torres detected elevated levels of carbon monoxide and ammonium on Kelemane's planet during a series of scans, indicating evolutionary progress by the planet's inhabitants. (VOY: "Blink of an Eye")