Fertilizer granulation is the process of turning powdered or lumpy fertilizer raw materials into granules. It is a key step in fertilizer production, improving both the physical properties of the fertilizer and its application effectiveness. Its core principle is to use mechanical force, binding action, or chemical reactions to aggregate dispersed raw materials into particles with a certain strength and size, facilitating storage, transportation, and application.

There are four main types of common granulation methods: First, drum granulation, where a rotary drum granulator tumbles the material and adds a binder to bind the raw materials into granules. This method is suitable for organic fertilizers and compound fertilizers, producing round granules that require drying. Second, extrusion granulation, which uses a double roller press  granualtors to forcefully extrude the raw material into strips, which are then cut into granules. No water needs to be added, making it suitable for heat-sensitive or high-concentration fertilizers. Third, disc granulation, which uses the rotational force of an inclined disc to gradually agglomerate the material into granules under centrifugal force. This method is flexible and suitable for small to medium-scale production. Fourth, spray granulation, which atomizes the raw material slurry and then dries it into granules with hot air. The granules are fine and uniform, and are often used for solidifying liquid fertilizers.

The advantages of granulated fertilizers are significant: reduced dust loss during transportation, improved fertilizer utilization; the granular structure facilitates control of nutrient release rate, such as slow-release fertilizers which often achieve slow nutrient release through granulation; and easier, more even application, avoiding localized high concentrations that could burn crops. Furthermore, functional ingredients (such as humic acid and beneficial bacteria) can be added during the granulation process to expand the multifunctionality of fertilizers.

With the increasing demand for precision fertilization in agriculture, fertilizer granulation is developing towards intelligent and customized methods. By adjusting particle size, hardness, and nutrient ratios, it meets the needs of different crops and soils, becoming an important link between fertilizer production and agricultural application.