Ammonia occurs naturally and is produced by human activity. It is an important source of nitrogen which is needed by plants and animals. Bacteria found in the intestines can produce ammonia. It is a colorless gas with a very distinct odor. This odor is familiar to many people because it is used in with salts, many household and industrial cleaners, and window-cleaning products. Ammonia gas can be dissolved in water. This kind is called liquid or aqueous . Once exposed to open air, liquid substance quickly turns into a gas. This chemical is applied directly into soil on farm fields, and is used to make fertilizers for farm crops, lawns, and plants. Many household and industrial cleaners containing its formula.