Di-Ammonium Phosphate (DAP) Fertiliser

DAP is the most popular phosphatic fertiliser due to its high nutrient content and favourable physical properties. The standard composition of DAP is:

• Nitrogen (N): 18%
• Phosphorus Pentoxide (P₂O₅): 46%

Hindalco, within the same facility, also produces nitrogen phosphorus potassium (NPK) complexes as value-added downstream products. These include:

• 10:26:26
• 12:32:16
• 20:20:0

In the Rift Valley, DAP is the traditional fertiliser used for planting maize and wheat. However, during the current planting season, DAP was not available in the stores of the National Cereals Board. Extension officers encouraged farmers to use the available NPK (23:23:0), which contains:

• Nitrogen (N): 23%
• Phosphorus Pentoxide (P₂O₅): 23%

They argued that NPK is a better option because it does not contribute to soil acidity. Farmers, however, preferred DAP, stating it is the fertiliser they trust.

In truth, NPK fertiliser is more concentrated in nitrogen but weaker in phosphate than DAP. Considering farmers have consistently used DAP over the years, the soils may no longer require high phosphate input. A phosphate fixation capacity test can help determine whether phosphorus fertilisation is necessary each season.

The claim that NPK is superior because DAP increases soil acidity remains highly debatable.