Qingdao Keyuan Agriculture Technology Co., Ltd. 

Fertilizers are mainly divided into three categories: chemical fertilizers, organic fertilizers, and biological fertilizers.

Chemical fertilizers: Made from minerals, air, water, etc., through chemical and mechanical processing, they are characterized by high nutrient content, rapid effect, and easy absorption by crops. However, they contain fewer types of nutrients, mainly providing inorganic nutrients. Long-term use may lead to soil compaction and nutrient imbalance.

Subcategories:

- Nitrogen fertilizer: Promotes the growth of crop stems and leaves, and promotes protein synthesis.

- Phosphorus fertilizer: Promotes root development, and promotes flowering and fruiting.

- Potassium fertilizer: Enhances stress resistance, and improves the crop's ability to withstand cold, drought, lodging, and pests and diseases.

- Compound fertilizers: Contain two or more major nutrients such as nitrogen, phosphorus, and potassium.

- Micronutrient fertilizers: Supplement essential micronutrients for crops, such as boron, zinc, and iron.

Organic Fertilizer: Derived from animal and plant residues, livestock and poultry manure, etc., it is rich in nutrient elements and has a long fertilizer efficiency. It contains a large amount of organic matter, which can improve soil structure and increase soil fertility. With comprehensive and balanced nutrient types, it imposes little burden on soil and crops. However, it has relatively low nutrient content and slow fertilizer efficiency, and is prone to decay. If not fully composted, they may contain pathogens or parasites.

Bio-fertilizers: These contain specific beneficial microorganisms that provide or improve crop nutrient conditions through microbial activities. However, their effectiveness is greatly influenced by environmental factors.

It is recommended to use them in combination: organic fertilizers for soil improvement, and chemical fertilizers for precise nutrient supplementation to enhance overall efficiency and nutrient utilization. 

Compound fertilizer: It is a high-efficiency fertilizer produced through chemical reactions that uniformly combine nutrients such as nitrogen, phosphorus, and potassium. Each granule has a consistent nutrient ratio, with uniform granule hardness and specific gravity.

Blended fertilizer (BB fertilizer): It is made by physically mixing two or more basic fertilizers (such as urea, diammonium phosphate, potassium chloride, and may also include compound fertilizer) via mechanical means. It is mostly granular in shape, and can also be strip-shaped or flake-shaped. No chemical reaction is involved in the production process, and its nutrients are in a dispersed state.

Compound fertilizer mainly relies on granulation processes for shaping. The four most common processes are as follows, each with its own characteristics:

1. High-tower granulation

Characteristics: Smooth and round granules, fast dissolution, and uniform nutrient distribution.

Brief description: The raw material is melted and sprayed from the top of a high tower, cooling and solidifying into granules as it falls, like "water droplets forming beads."

2. Drum granulation

Characteristics: High output, high granule strength, and less prone to breakage.

Brief description: The material is continuously tumbled, squeezed, and bound into granules inside a rotating large drum.

3. Disc granulation

Characteristics: Uniform granules, flexible and intuitive operation.

Brief description: A mist of water is sprayed into an inclined disc, causing the powder to roll and adhere, like a "snowball" growing larger.

4. Spray granulation

Characteristics: Drying and granulation are completed simultaneously, energy-saving and efficient.

Brief Description: The concentrated slurry is atomized and sprayed into hot air, where the moisture evaporates instantly, directly yielding dry granules.

These processes ensure that compound fertilizers can form regular, efficient granules to meet the fertilization needs of different crops.

It is a compound fertilizer containing both nitrogen and phosphorus, suitable for promoting crop growth and root development.

It is a compound fertilizer containing both nitrogen and potassium, suitable for improving crop resistance and quality.

In addition to nitrogen, phosphorus, and potassium, it also contains micronutrients such as zinc and iron, providing a comprehensive supply of nutrients.

It helps improve the utilization rate of nitrogen, phosphorus, and potassium, enhances crop adaptability, and increases crop yield. Seaweed fertilizer also contains abundant alginic acid, mannitol, phenolic substances, and other bioactive substances, which can promote plant absorption and growth.

Reference factors: Crop nutrient requirements (e.g., root crops need more potassium, leafy vegetables need more nitrogen), soil nutrient supply capacity (small amounts frequently in sandy soils, heavy base fertilizer in clay soils), target yield, fertilizer utilization rate (conventional fertilization achieves 30%~70% nitrogen, phosphorus, and potassium utilization rate, drip irrigation can reach 80%).

Specific standards: 80~200 kg/mu of organic fertilizer, 40~60 kg/mu of compound fertilizer for field crops (50~100 kg/mu for cash crops), and 3~6 kg/mu/application of water-soluble fertilizer.

Rice: Tillering stage + young panicle differentiation stage. Divided into three periods: early, middle, and late. The focus is on topdressing during the tillering stage to ensure effective tillering and strong stems.

Sugarcane: Elongation stage. This is the period of maximum nutrient demand, requiring heavy application of fertilizer to promote stem growth, accounting for the majority of total nutrient requirements. Nutrient requirements are lower in the early stage, higher in the middle stage, and lower in the late stage.

Maize: Large trumpet stage. This is the most critical period for topdressing (especially nitrogen fertilizer), crucial for yield formation. Pay attention to topdressing during the seedling stage, jointing stage, and large trumpet stage.

Oil palm: Requires nutrients increasing with tree age. Nutrient requirements increase significantly from the third year after planting, with particular emphasis on potassium fertilizer.

Rubber: Young tree stage + mature trees twice a year. Fertilization of young trees affects long-term yield; mature trees are typically fertilized twice a year, in spring and autumn.

Key points: Focus on fertilization during the mid-growth stage when crop nutrient requirements are most vigorous (such as the elongation stage of sugarcane and the large trumpet stage of corn), and develop long-term fertilization plans that match the age of perennial crops (such as fruit trees).

Nitrogen fertilizer: Apply deeply and cover with soil to prevent volatilization. Do not water immediately after applying urea.

Phosphorus fertilizer: Mix with organic fertilizer; apply as a base fertilizer in concentrated strips or furrows; prioritize application to overwintering crops and legumes.

Potassium fertilizer: Apply to potassium-loving crops such as potatoes and tobacco.

Compound fertilizers are usually in granular form and require decomposition by soil microorganisms to release nutrients, which are then absorbed by the plant's roots. They are generally applied before sowing or during the growing season and mixed with the soil.

Compound fertilizer release nutrients relatively slowly, allowing it to continuously supply plants with their nutritional needs for months or even years.