Difference Between DAP and NPK Fertilizer

The key difference between DAP and NPK fertilizer is that the DAP fertilizer has no potassium whereas the NPK fertilizer contains potassium as well.

The term DAP refers to diammonium phosphate, and it is a phosphate fertilizer; the world’s most common phosphorus fertilizer. Thus, we produce this fertilizer using two important constituents in the fertilizer industry; phosphoric acid and ammonia. NPK fertilizers, on the other hand, are an important source of nitrogen, potassium and phosphorus. These are the three primary nutrients that the crops need for their growth and development.

CONTENTS

1. Overview and Key Difference
2. What is DAP Fertilizer
3. What is NPK Fertilizer
4. Side by Side Comparison – DAP vs NPK Fertilizer in Tabular Form
5. Summary

What is DAP Fertilizer?

DAP fertilizers are sources of nitrogen and phosphorous that have wide usage in agricultural purposes. The major component in this fertilizer is diammonium phosphate that has the chemical formula (NH4)2HPO4.  Moreover, the IUPAC name of this compound is diammonium hydrogen phosphate. And it is water-soluble ammonium phosphate.

In the production process of this fertilizer, we react phosphoric acid with ammonia, which forms a hot slurry that is then cooled, granulated and sieved to get the fertilizer that we can use in the farm. Moreover, we should proceed with the reaction under controlled conditions because the reaction uses sulfuric acid, which is dangerous to handle. Therefore, the standard nutrient grade of this fertilizer is 18-46-0. This means, it has nitrogen and phosphorous in the ratio of 18:46, but it has no potassium.

Typically, we need approximately 1.5 to 2 tons of phosphate rock, 0.4 tons of sulfur (S) to dissolve the rock, and 0.2 tons of ammonia for the production of DAP. Moreover, the pH of this substance is 7.5 to 8.0. Therefore, if we add this fertilizer to the soil, it can create an alkaline pH around the fertilizer granules that dissolve in soil water; thus the user should avoid adding a high amount of this fertilizer.

What is NPK Fertilizer?

NPK fertilizers are three component fertilizers that are very useful for agricultural purposes. This fertilizer acts as a source of nitrogen, phosphorus and potassium. Therefore, it is an important source of all three primary nutrients that a plant requires for its growth, development and proper functioning. The name of this substance also expresses the nutrient that it can supply.

NPK rating is the combination of numbers that gives the ratio between nitrogen, phosphorous and potassium provided by this fertilizer. It is a combination of three numbers, separated by two dashes. For example, 10-10-10 indicates that the fertilizer provides 10% of each nutrient. There, the first number refers to the percentage of nitrogen (N%), the second number is for phosphorous percentage (in the forms of P2O5%), and the third is for potassium percentage (K2O%).

What is the Difference Between DAP and NPK Fertilizer

DAP fertilizers are sources of nitrogen and phosphorous which have wide usage in agricultural purposes. These fertilizers contain diammonium phosphate – (NH4)2HPO4. This acts as a source of nitrogen and phosphorus. Whereas, NPK fertilizers are three component fertilizers that are very useful for agricultural purposes. It contains nitrogenous compounds, P2O5 and K2O. Moreover, it is a major source of nitrogen, phosphorous and potassium for agricultural purposes.

The below infographic presents the detailed difference between DAP and NPK fertilizer in tabular form.

Summary – DAP vs NPK Fertilizer

DAP and NPK are very important fertilizers. We use them as sources of nutrients for crops in agriculture. The key difference between DAP and NPK fertilizer is that the DAP fertilizer has no potassium whereas the NPK fertilizer contains potassium as well.

Reference:

1. “Diammonium Phosphate | Mosaic Crop Nutrition.” Manganese In Crop Production | Mosaic
Crop Nutrition. Available here 
2. Feeco. “NPK Fertilizer: What Is It and How Does It Work?” FEECO International Inc.,
12 Dec. 2017. Available here  

Image Courtesy:

1.”DAP Ả Rập”By Muibu88 – Own work, (C BY-SA 4.0) via Commons Wikimedia  
2.”Flexible intermediate bulk containers-Fertilizer”By Cjp24 – Own work, (CC BY-SA 3.0) via Commons Wikimedia