(1) Although some fertilizers are well-known, they are actually used in some sets of certificates, and there are bound to be mistakes in production, such as reducing materials. So the standard is to go to the National Fertilizer Inspection Center to check whether the certificates are complete and consistent with the fertilizers you see, because every fertilizer certificate is not so easy to be audited. In the fertilizer market, there are all certificates of water-soluble fertilizers involved in the new land of Germany.
(2) Whether the raw materials are good or not, water-soluble fertilizers are divided into macro-elements, medium-trace elements and humic acid. Among them, potassium is the main element, and potassium dihydrogen phosphate and potassium nitrate are good water-soluble fertilizers, which are absorbed by crops.
(3) From the point of water solubility, adding fertilizer into water, stirring and dissolving to see whether there is impurity precipitation, no impurity, clear liquid, which has a good advantage in foliar fertilization and absorption and utilization.