The simple identification method is as follows: Look at the package. Fertilizer packaging bags must be marked with product name, nutrient content, grade, trademark, net weight, factory name, address, standard code and production license number. If the above signs are missing or incomplete, it may be fake fertilizer or inferior products. Second, look at the appearance. Domestic potassium chloride is a white crystal, which is pale yellow when it contains impurities. Imported potassium chloride is mostly white crystals or red and white crystals. Potassium sulfate is a white crystal, which is pale yellow or grayish white when containing impurities. Third, look at water solubility. Take 1g potassium chloride or calcium sulfate and potassium dihydrogen sulfate, put them into a clean glass or white porcelain bowl, add 10ml clean cold boiled water, fully stir them evenly, and observe the dissolution. All dissolved potash fertilizer without impurities can't be dissolved quickly, and those with porridge or precipitation are inferior potash fertilizer or fake potash fertilizer. Charcoal test. Take a small amount of potassium chloride or potassium sulfate and put it on red-hot charcoal or cigarette butts. It should not burn or melt and crackle. Without this phenomenon, it is a fake and shoddy product. Now it is found that some people pass salt off as potassium dihydrogen phosphate. Take some samples and put them on a small iron plate and burn them. If the flame is yellow, it may contain salt. Lime water test. Some manufacturers use ammonium phosphate with a small amount of potassium fertilizer, or even no potassium fertilizer, and mix them together to fake potassium dihydrogen phosphate. Potassium dihydrogen phosphate with good quality is white crystal. After adding lime water (or plant ash water), there is no smell of ammonia. If it is white or off-white, it smells of ammonia after adding lime water (or plant ash water), which is fake potassium dihydrogen phosphate. Six copper wires are tested. Dip a small amount of potassium chloride or potassium phosphate into copper wire or electric furnace wire crystallized from roots and burn it on a liquid flame. Through the blue glass, you can see the purple flame. Without this phenomenon, it is a fake and shoddy product.