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How Do You Make Granular Fertilizer for Optimal Plant Growth?

Author : Jordan Last Updated :

Chemical fertilizer is a type of fertilizer in the form of dry solid pellets that provide essential nutrients to plants and improve soil properties. It releases nutrients over weeks to months, feeding plants gradually.

Like liquid fertilizers, it contains 3 essential nutrients namely nitrogen (N), phosphorus (P), and potassium (K). The lack of any element will affect the normal growth and development of crops.

NPK elements Effects Element deficiency
Nitrogen Promote cell division and growth The plants are short and thin with yellowish-green leaves
Phosphorus Promote sugar movement and strengthen roots and blooms The plants are small, low in sugar, and the seed wilt.
Potassium Promote photosynthesis and improve the plants' cold, disease, and lodging resistance The plants are withered, soft tissue, and easy to lodge

Therefore, agriculture cannot be developed without fertilizers. Granular fertilizers are essential for increasing crop yields. This blog is a step-by-step guide to Granular Fertilizers Production Process.

Step 1 Mixing of the fertilizer ingredients

Based on the soil analysis, you can identify the specific nutrients required to supplement the soil and determine the nutrient ratios. Once the raw materials are acquired, it is time to create the granular fertilizer blend.

Use a mixer to obtain a homogeneous mixture. The uniform mixing of fertilizers not only refers to the individual mixing of new substances like nitrogen, phosphorus, and potassium, but also includes the mixing of new substances and returned substances.

The granulated fertilizers can be divided into two types according to their composition.

1. Nitrogen fertilizer, phosphorus fertilizer, potash fertilizer, and compound fertilizer (NPK fertilizer)

Nitrogen fertilizer, phosphorus fertilizer, potash fertilizer, and compound fertilizer (NPK fertilizer)

Common ingredients in this type of granular fertilizer include urea (nitrogen), phosphate rock (phosphorus), potassium chloride (potassium), and various sources of micronutrients like iron, zinc, and manganese.

Raw materials such as urea, ammonium nitrate, ammonium chloride, ammonium sulfate, ammonium phosphate (monoammonium phosphate, diammonium phosphate, coarse whiting, single superphosphate), potassium chloride (potassium sulfate), etc. shall be provided at a certain ratio (according to market demand and soil test results in various regions).

Organic fertilizer granules

This fertilizer has recently become more popular. It is to convert high-moisture organic matter like livestock manure, crop straw, household garbage, and sludge into pellets that are easy to spread on fields, lawns, and gardens. 

Note: The organic fertilizer should be fermented for 15-20 days before crushing.

Organic fertilizer granules

1. Livestock manure: Manures from chicken, pig, cow, sheep, rabbit, etc.

2. Crop straw: Important fertilizer component, containing N, P, K, Ca, S, and other nutrients necessary for crops.

3. Household garbage: Leftovers, rice washing water, discarded fruits and vegetables, expired dairy products, etc.

4. Cake fertilizer raw materials: Cake from rapeseed, cottonseed, bean, sesame, castor, tea seed, etc.

5. Sludge: Unpolluted mud from rivers, ponds, ditches, ports, lakes, etc.

Step 2 Crushing of chemical fertilizer

FTM Machinery roller crushers, hammers crushers, double stage crushers, and compound crushers are all suitable for the crushing of various medium-hard materials in the production of compound fertilizers, organic-inorganic compound fertilizers, and organic fertilizers.

The roller crusher has a large crushing ratio of 4:1. Its output particle size can be as fine as 2 mm, and the output can reach 110 tons per hour. The hammer crushers have a larger production, which can be up to 1,200 tons per hour.

Granular fertilizer crushers

In addition, FTM Machinery fertilizer crushers are made of high-quality wear-resistant steel, and the inlet and outlet ports are designed reasonably, easy to clean. They can crush the fertilizer evenly, and the fertilizer is not easy to stick to the wall. Get the Latest Price

Step 3 Fertilizer granulation

Fertilizer granulation is made by mixing various nutrient salts needed for plant growth, such as ammonium nitrate, ammonium phosphate, and potassium chloride, to form a slurry in a large container known as a granulator.

Granulation can prevent ingredients separation, dust loss during fertilization, and solidification caused by moisture absorption and heavy pressure during storage. It can improve fertilizer performance and prolong fertilizer efficiency.

The granulation equipment commonly used in the fertilizer industry can be divided into disc granulation, drum granulation, and spray granulation. Among them, the disc granulator is the most popular among small and medium-sized plants.

Granular fertilizer disc granulator

The principle of the disc pan granulator is to roll the mixed material in an inclined disc with water and binder, creating various sizes of fertilizer granules. Get the Latest Price

FTM Machinery disc granulator achieves a productivity of 4-24 tons per hour and boasts these distinct features:

1. Automatic classification according to particle size

2. Hard and uniform product, with an intact particle shape

3. Simple operation and maintenance

4. Eco-friendly, energy-efficient, and durable

5. Affordable and compact. Costs 2/3 of comparable granulators, with a much smaller footprint

Step 4 Drying of the fertilizer

After granulation, the newly formed granules contain excess moisture. Proper drying is essential to prevent granular fertilizer caking and ensure pellet stability during storage.

FTM Machinery dryers have drying and secondary granulation functions. The material increases the solubility of its original moisture to the fertilizer by increasing the temperature. Granular fertilizers have the characteristics of a high granulation rate, uniform size, and low water content.

Granular fertilizer dryer

The dryer is equipped with a guide area, secondary granulation polishing area, 180° pre-drying area, 135° drying area, 135°/120° staggered drying area, 120° drying area, and 120°/90° staggered drying area at the exit. It ensures that the wet and soft particles will not be damaged after granulation, and improve the drying efficiency.

The water of the dried product is preferably 1.0%-1.5%. The optimal temperature difference between the dryer head and tail is 100℃. The exhaust gas temperature should be controlled at 65-80℃ with a plus or minus deviation of 1°C. Get the Latest Price

Step 5 Cooling and screening of the fertilizer

The dried material is transported to a cooler by a belt conveyor for cooling. The cooling process mainly uses the blower to send the natural air through the pipeline to the cooler to cool the material.

Granular fertilizer cooler and screen

After cooling, the material is screened using a trommel screen for screening. Large crushed particles and unqualified powder are re-granulated, while qualified fertilizer goes to automatic packaging. Get the Latest Price


Chemical fertilizer production involves batching, mixing, crushing, granulation, drying, cooling, and screening. This is just a brief introduction to some simple chemical fertilizer production process flow. If necessary, please contact FTM Machinery and we provide equipment for the fertilizer production line.

FAQ about fertilizer (compound fertilizer and organic fertilizer) granulation process

1. What are the requirements for compound fertilizer formula design?

① The viscosity of the material in the formula is the basis of granulation.

  • When low-concentration fertilizer is produced by using superphosphate as the phosphorus source, the conditioning agent of superphosphate and viscous material should be greater than 50%.
  • When high-concentration compound fertilizer is produced by using ammonium phosphate as the phosphorus source, the conditioning agent of ammonium phosphate and viscous material should not be less than 40%.
  • The urea formula depends on the amount of urea. The proportion of viscous materials in high-viscosity urea is generally about 35%.

② The ingredients used in the formula must be conducive to improving the roundness of the particles.

The decomposition and softening temperature of dispersive materials (potassium chloride, ammonium chloride, potassium sulfate, ammonium sulfate, etc.) are relatively high, which can increase the strength of the particles in the dryer and play a key role in improving the roundness of the particles. The sum of dispersible materials in the formula should account for more than 35%.

2. How long does the fertilizer stay in the dryer?

The residence time of materials in the dryer should be generally greater than 22 min. Under the same condition, the longer the dryer barrel, the longer the material residence time and the higher the heat energy utilization ratio.

FTM Machinery dryers

FTM Machinery dryers

Therefore, lengthening the dryer barrel is very beneficial to make full use of thermal energy. It is an effective way to solve the problem that the setting of granulation and pelletizing area affects the drying function.

3. What is the most suitable drying temperature during organic fertilizer processing?

To avoid the death of effective live bacteria due to excessive temperature during the drying process, the drying temperature of the material should not be higher than 60℃ (generally 50℃).

For this reason, the temperature of the hot air in contact with the material should be different according to the moisture content of the material, generally no more than 130℃, so that the hot air temperature can be controlled in sections to improve the thermal efficiency as well as avoid the death of effective live bacteria.

4. What are the factors that affect the granulation of fertilizer disc granulators?

The main factors influencing the granulation of fertilizer disc granulators are mainly the diameter of the disc, the height of the side of the disc, the inclination of the disc, the rotating speed, and the water addition.

FTM Machinery fertilizer disc granulators

FTM Machinery fertilizer disc granulators

The ratio of side height and diameter of the disc granulator is generally 0.12-0.17. Its diameter can be calculated from the production intensity obtained from the test or actual production assessment.

The inclination of the disc granulator is determined according to the natural angle of repose of the wet powder before granulation. For example:

The natural angle of repose of potassium chloride is 36°; dipotassium phosphate is 31°; coarse whiting is 31°-35°.

When the inclination is less than the natural angle of repose of the wet powder, the material will stick to the disc; however, as the inclination increases, the rotation speed increases, the material residence time becomes shorter, and the overflow particle size becomes smaller, so it should be determined according to specific conditions, generally 40°-60°.

Increasing the disc rotation speed can increase the granulation rate of fertilizers.

As the amount of water added increases, the granulation rate of fertilizer first increases and then decreases. The smaller the particle size of raw materials, the higher the granulation rate.

5. Examples of Granular Fertilizers

a. Nitrogen-based fertilizer: It includes urea, ammonium nitrate, and ammonium sulfate.

b. Phosphorous-based fertilizer: It includes monoammonium phosphate, diammonium phosphate, and triple superphosphate.

c. Potassium-based fertilizer: It includes chloride and potassium sulfate.

d. Compound fertilizer: It contains a combination of nitrogen, phosphorous, and potassium (NPK) in specific ratios that are tailored to the needs of different crops. These fertilizers are often labeled with their NPK ratio, such as 10-10-10 or 20-20-20.

e. Specialty fertilizer: It is formulated for specific crops or soil types and contains additional micronutrients or trace elements. It is targeted to address specific nutrient deficiencies or to improve the overall fertility of the soil. Examples of specialty fertilizers include lime, gypsum, and sulfur.

Author : Jordan Jordan is the writer of the blog with a broad knowledge of this industry. Most importantly, he hopes to help you in your projects sincerely.

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