2026/07/09
Q1: What is the fundamental difference in solubility between water-soluble fertilizer and ordinary compound fertilizer?
A: Solubility is the most fundamental difference between the two. Ordinary compound fertilizer is made from diammonium phosphate, urea, potassium chloride, or potassium sulfate through physical granulation. It contains a large amount of insoluble fillers (such as talc and kaolin), resulting in slow dissolution and significant precipitation. Water-soluble fertilizer, on the other hand, requires 100% water solubility. Its raw materials include high-purity potassium dihydrogen phosphate and potassium nitrate, with a water-insoluble content typically below 0.5%. It can be directly used in precision irrigation systems such as drip irrigation and sprinkler irrigation without clogging sprinkler heads.
Q: What are the differences in nutrient composition and absorption efficiency between the two?
A: Ordinary compound fertilizer has a relatively simple nutrient composition, mainly focusing on nitrogen, phosphorus, and potassium macronutrients. Phosphorus is mostly reactive, with an absorption and utilization rate typically around 30%. Water-soluble fertilizers are mostly "complete nutrition" formulas. Besides high concentrations of mineral nutrients, they typically include chelated trace elements (such as EDTA/EDDHA-chelated iron, zinc, manganese, and copper). These elements are less easily fixed in the soil, resulting in significantly higher absorption rates. The electrical conductivity (EC value) of water-soluble fertilizers is easier to control, allowing for immediate nutrient supply and increasing utilization to 70%-80%.
Q: What are the differences in their production processes?
A: Ordinary compound fertilizers are mainly produced through physical processes such as drum granulation, disc granulation, or extrusion granulation. During granulation, binders or steam are added to assist in granulation, and the requirements for raw material purity and fineness are relatively relaxed. The production of water-soluble fertilizers, however, has extremely strict requirements for raw material purity and process control—trace elements must be pre-chelated, the reaction process requires precise temperature and pH control, equipment must be made of 316L stainless steel for corrosion prevention, and the finished product must pass rigorous testing for water-insoluble matter.
Q: What are the respective application scenarios for each? A: Ordinary compound fertilizers are mostly used as base fertilizers, offering long-lasting effects but slow release, suitable for broadcasting or tilling into the soil. Water-soluble fertilizers, on the other hand, are primarily used as top dressings. Combined with fertigation technology, they can be precisely delivered to crop roots through drip irrigation or sprinkler irrigation systems, and can also be used for foliar spraying. Water-soluble fertilizers have extremely rapid effects, showing results within days of application, greatly reducing nutrient loss and fixation in the soil.
Q: How to choose between water-soluble fertilizers and ordinary compound fertilizers based on planting needs?
A: If crops are in the early growth stage requiring long-lasting nutrient supply, or if the planting area is large and irrigation facilities are inadequate, ordinary compound fertilizers are an economical and practical choice as base fertilizers. If crops are in the flowering and fruiting stage requiring rapid nutrient replenishment, or if drip irrigation or sprinkler irrigation systems are in place, and precision fertilization and high utilization rates are desired, water-soluble fertilizers are a better choice. The two are not substitutes, but rather complementary combinations of base and top dressing – ordinary compound fertilizer as a base, followed by water-soluble fertilizer as a top dressing, is a scientific fertilization strategy for achieving high yields and quality.
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