Ammonium dihydrogen phosphate（MAP）. It's a white crystal. When heated, it will be decomposed into ammonium metaphosphate (nh4po3), which can be made by reacting ammonia with phosphoric acid. It is used as a fire retardant for phosphate fertilizer, wood, paper and fabric (such as the extinguishant for matchstick and candle wick), and also for making medicine. Also used as feed additive for ruminant.