One is to place the controlled release fertilizer and the common compound fertilizer in two glass filled with water, and gently stir for a few minutes. The compound fertilizer will dissolve faster, the particles will become smaller or completely dissolved, and the water will appear cloudy. Fertilizer will not dissolve, and the water quality is clear, no impurities, and bubbles appear around the particles.
Second, because the core of controlled-release fertilizer is nitrogen-phosphorus-potassium compound fertilizer, controlled-release fertilizer with shell peeled off will be dissolved quickly in water. If the shell is insoluble, it is inferior fertilizer or fake fertilizer.
The third is not distinguishable by color. Some manufacturers take control of the color of controlled-release fertilizers, and make common fertilizers the same color as controlled-release fertilizers. If they are put in water, controlled-release fertilizers are decolored and the water quality is turbid and colored, it means that they are products for preventing influenza and true controlled-release fertilizers. The outer membrane is not bleached.
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