Phosphorus is a cornerstone of healthy plant growth, playing a vital role in everything from root development to the production of flowers and seeds. Without enough phosphorus, your crops simply won't thrive. When it comes to providing this essential nutrient, Monoammonium Phosphate (MAP) and Diammonium Phosphate (DAP) are two of the most popular fertilizer choices.

While they may seem similar, a key difference between them can have a significant impact on your crop's success. This guide will break down the characteristics of MAP and DAP to help you choose the best option for your specific agricultural needs.

What is Monoammonium Phosphate (MAP)?

MAP is a fertilizer with the chemical formula NH4​H2​PO4​. Its typical nutrient analysis is 11-52-0, meaning it contains 11% nitrogen, 52% phosphorus (P2​O5​), and 0% potassium.

The most notable characteristic of MAP is its acidity. When it dissolves in soil, it creates a lower pH environment around the fertilizer granule. This is a huge benefit in alkaline or high-pH soils because it helps to solubilize phosphorus, making it more available for your plants to absorb. With its high phosphorus-to-nitrogen ratio, MAP is an excellent starter fertilizer, providing a phosphorus-rich boost that is crucial for young plants and root development.

What is Diammonium Phosphate (DAP)?

DAP is another common fertilizer with the chemical formula (NH4​)2​HPO4​. Its standard nutrient analysis is 18-46-0, containing 18% nitrogen, 46% phosphorus (P2​O5​), and 0% potassium.

Unlike MAP, DAP is alkaline when it dissolves in the soil. This makes it an ideal choice for acidic or low-pH soils, as its higher pH helps to neutralize the soil in the immediate vicinity of the fertilizer. With a more balanced nitrogen and phosphorus content, DAP is a versatile option for both starter applications and for maintaining nutrient levels in established crops.