What is the Difference Between DAP and NPK Fertilizer

The main difference between DAP and NPK fertilizers is that DAP is a specific type of fertilizer that contains high levels of nitrogen and phosphorus, while NPK fertilizers are general fertilizers that contain varying ratios of nitrogen, phosphorus, and potassium, along with other minor nutrients, to cater to different plant growth stages and specific crop needs.

Key Areas Covered

1. What is DAP Fertilizer
     – Definition, Composition, Features
2. What is NPK Fertilizer
    – Definition, Composition, Features
3. Similarities Between DAP and NPK Fertilizer
    – Outline of Common Features
4. Difference Between DAP and NPK Fertilizer
     – Comparison of Key Differences

Key Terms

DAP Fertilizer, NPK Fertilizer

Difference Between DAP and NPK Fertilizer - Comparison Summary

What is DAP Fertilizer

DAP stands for “Di-Ammonium Phosphate.” It is a commonly used fertilizer in agriculture and horticulture. DAP is a type of water-soluble fertilizer that contains two essential nutrients for plant growth: nitrogen and phosphorus.

The chemical formula of DAP is (NH4)2HPO4, which indicates that it is composed of ammonium ions and phosphate ions. The presence of both ammonium and phosphate makes DAP an effective source of nitrogen and phosphorus, two vital elements required for plant development. The nitrogen in DAP is in the ammonium form, which is easily absorbed by plant roots and helps in promoting early plant growth, vegetative development, and overall plant vigor. The phosphorus in DAP is crucial for root formation, flower and fruit development, and energy transfer within the plant.

DAP vs NPK Fertilizer

DAP is often used as a starter fertilizer during the early stages of plant growth to provide the necessary nutrients for strong root development and healthy plant establishment. It is widely used in various crops, such as cereals, vegetables, fruits, and legumes.

Due to its water solubility, DAP can be applied directly to the soil or used as a foliar spray, depending on the specific needs of the plants and the soil conditions. Its popularity is attributed to its ability to supply nitrogen and phosphorus simultaneously, which makes it a convenient and effective fertilizer for many agricultural practices.

What is NPK Fertilizer

NPK fertilizer is a type of plant nutrient formulation that combines three essential elements necessary for healthy plant growth: nitrogen (N), phosphorus (P), and potassium (K). These three nutrients play crucial roles in various physiological processes within plants, contributing to the overall development, yield, and quality of crops.

Nitrogen (N) is responsible for promoting leafy growth and enhancing the vibrant green color of foliage. It is a fundamental component of amino acids, which are the building blocks of proteins, crucial for plant cell structure and function. Phosphorus (P) is essential for root development, flowering, and fruiting. It aids in energy transfer and storage, as well as DNA and RNA synthesis, playing a pivotal role in the overall metabolic processes of plants. Potassium (K) contributes to various physiological functions, such as water uptake, nutrient transportation, and disease resistance. It enhances the plant’s ability to withstand stressors like drought, pests, and diseases.

Compare DAP and NPK Fertilizer

NPK fertilizers are formulated with specific ratios of these three nutrients, tailored to different stages of plant growth and the specific requirements of various crops. Commonly expressed as three-digit numbers on fertilizer labels (e.g., 10-20-10 or 20-10-10), these ratios indicate the percentage of nitrogen, phosphorus, and potassium present in the fertilizer. Before application, a soil test is crucial to determine the optimal NPK ratio and dosage. Matching fertilizer formulation to crop needs and soil status enhances effectiveness, and split dosing may benefit certain crops, managing nutrients better. Application methods like broadcasting, banding, side-dressing, or foliar spraying are chosen based on crop and nutrient requirements.

Similarities Between DAP and NPK Fertilizer

  • Both DAP and NPK fertilizers contain essential nutrients necessary for plant growth. These nutrients include nitrogen (N), phosphorus (P), and potassium (K).
  • They contribute to improved plant development by supplying nutrients vital for root growth, overall health, and reproductive processes.
  • Both fertilizers help enhance crop yield and quality by addressing nutrient deficiencies that can limit growth and production.

Difference Between DAP and NPK Fertilizer


DAP is a fertilizer containing nitrogen and phosphorus with a fixed nutrient ratio, often used for promoting root growth and early plant development. NPK Fertilizers are a group of fertilizers providing a balanced combination of nitrogen, phosphorus, and potassium, essential for overall plant growth and development.

Nutrient Composition    

DAP primarily provides nitrogen and phosphorus. It has a fixed nutrient ratio of approximately 18-46-0, meaning it contains 18% nitrogen and 46% phosphorus by weight, with no potassium. On the other hand, NPK fertilizers offer a balanced combination of three essential nutrients: nitrogen, phosphorus, and potassium. They come in various formulations with different ratios, such as 10-10-10, 20-10-10, 10-20-10, etc.

Immobility in Soil          

Phosphorus in DAP is relatively immobile, remaining within the root zone and available for plant uptake. NPK fertilizers provide a mix of mobile and immobile nutrients. While nitrogen and potassium are relatively mobile in the soil and can move with water to reach plant roots, phosphorus remains less mobile.

Root Growth and Development 

DAP is commonly used to encourage root growth and support early plant development. It is especially beneficial for crops requiring ample phosphorus during initial growth stages. Meanwhile, NPK fertilizers are versatile and cater to specific crop needs across various growth stages. They contribute to overall plant growth, flowering, and fruiting phases.


DAP offers a fixed nutrient ratio and is primarily suited for early phosphorus needs in crops, whereas NPK fertilizers provide adaptable nutrient ratios that can be adjusted to meet specific crop requirements and growth stages.


The main difference between DAP and NPK fertilizer is that DAP is a specific type of fertilizer that contains high levels of nitrogen and phosphorus, while NPK fertilizers are general fertilizers that contain varying ratios of nitrogen, phosphorus, and potassium, along with other minor nutrients, to cater to different plant growth stages and specific crop needs.


1. “Diammonium Phosphate – An Overview.” Science Direct.
2. “NPK Ratio: What Do Numbers on Fertilizers Mean.” The Old Farmer’s Almanac.

Image Courtesy:

1. “DAP 18 46 0” By Iffco pr – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “Fertilizer- NPK-MS” By Mahsa-110 – Own work (CC BY 4.0) via Commons Wikimedia

About the Author: Hasini A

Hasini is a graduate of Applied Science with a strong background in forestry, environmental science, chemistry, and management science. She is an amateur photographer with a keen interest in exploring the wonders of nature and science.

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