Solid Granular Fertilizers: The Stable Backbone of Agriculture

In modern agricultural production, solid granular fertilizers, with their stable physical form and excellent adaptability, have become the most widely used fertilizer category. They are not only carriers of nutrients but also key media for achieving efficient, large-scale agricultural operations. From vast wheat fields to precise orchard management, these uniformly shaped granules support global grain and vegetable production with their unique advantages. Classification by Form: Size and Structure Define Function Solid granular fertilizers are not all the same; their particle size and internal structure determine different uses and effects. 1. Large-Granule Fertilizers This is the most common form, such as the familiar urea, diammonium phosphate (DAP), and general compound fertilizers. Their granules typically have a diameter of 2-4 mm and are firm and dense. This design makes them resistant to breakage, moisture absorption, and caking, with even nutrient distribution. The advantage of large granules lies in their "longevity." They dissolve relatively slowly and are primarily used as base fertilizers, deeply incorporated into the soil to provide a stable supply of basic nutrients throughout the crop's growing season, while also reducing losses from rainwater leaching. 2. Small-Granule / Bulk Blended (BB) Fertilizers These fertilizers have smaller particle sizes (1-2 mm) and are physically blended from single-nutrient granules (e.g., white nitrogen granules, red potassium granules) in specific ratios, hence the name "BB fertilizers." Their core advantage is formulation flexibility. Growers can customize the N-P-K ratio according to the needs of different crops and growth stages. They can be used both as base fertilizers and for mechanized precision top-dressing, making them an ideal choice for variable rate application and nutrient management. 3. Coated Granular Fertilizers This represents an advanced product of fertilizer technology, such as polymer-coated urea or sulfur-coated urea (SCU). By coating a regular fertilizer granule with a functional membrane (sulfur, polymer, etc.), they achieve precise control over the nutrient release rate. The thickness of this "coat" determines whether nutrients are released slowly over weeks or months. These fertilizers are mainly applied once as a base fertilizer, achieving "one-time application, full-season supply," greatly saving labor and significantly improving nutrient use efficiency while reducing environmental pollution risks.

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