Ammonium dihydrogen phosphate, with the chemical formula NH4H2PO4, is a chemical compound composed of ammonium ions (NH4+) and dihydrogen phosphate ions (H2PO4-). It is also known as monoammonium phosphate (MAP). It is a white crystalline solid that is highly soluble in water.

Ammonium dihydrogen phosphate is a widely used and important compound with various applications in agriculture, industry, and as a laboratory reagent. Some key properties and uses of ammonium dihydrogen phosphate include:

1. Fertilizer: Ammonium dihydrogen phosphate is commonly used as a fertilizer in agriculture. It provides essential nitrogen and phosphorus nutrients for plant growth, promoting healthy root development and improving crop yields.
2. Flame Retardant: It is used as a flame retardant in certain materials and products, including wood, paper, and textiles.
3. Buffering Agent: Ammonium dihydrogen phosphate is used as a buffering agent in various chemical and biological processes to maintain a stable pH level.
4. Food Additive: It is approved as a food additive in some countries and is used as a leavening agent in baking powders.
5. Industrial Applications: Ammonium dihydrogen phosphate is used in some industrial processes, such as in metal finishing and the production of chemicals.
6. Laboratory Reagent: It is used as a reagent in various laboratory experiments and analyses.

Ammonium dihydrogen phosphate is generally considered safe for its intended uses, but proper safety precautions should be followed when handling it. While it is not highly toxic, inhalation of its dust can irritate the respiratory system, and ingestion in large quantities can cause gastrointestinal discomfort.

As a fertilizer and flame retardant, ammonium dihydrogen phosphate plays a significant role in agriculture and industrial applications. Its versatility and usefulness make it an important compound in various fields, including chemistry, agriculture, and food processing.