How to distinguish between good and bad chemical fertilizers?

How to distinguish between good and bad chemical fertilizers? Please introduce the method can refer to the following methods to identify the quality of chemical fertilizer: 1, packaging identification method ① inspection marks: according to the relevant state departments, chemical fertilizer bags must be marked with product name, nutrient content, grade, trademark, net weight, standard code, factory name, factory address, production license number and so on. If the above signs are not or incomplete, it may be fake fertilizer or inferior fertilizer. ② check the seal of the bag: pay special attention to the fertilizer with obvious unsealing marks on the seal of the bag, this phenomenon may be adulterated. 2. Shape and color identification method ① urea: White or light yellow, showing granular, needle-like or prism-like crystals, no powder or little powder. ② ammonium sulfate: White or light-colored crystal. ③ ammonium chloride: White or yellowish crystal. ④ ammonium bicarbonate: White or grayish crystal. ⑤ superphosphate: dark gray, grayish white, light yellow and other loose powder, there are many small pores in the block. ⑥ calcium, magnesium, phosphate fertilizer: grayish white, grayish green, or grayish black powder that looks very fine. Crushed, vitreous-like objects can generally be seen in sunlight. ⑦ potassium sulfate: White crystal or powder. ⑧ potassium chloride: White or reddish particles. ⑨ zinc sulfate for agricultural use: needle-like crystals of white or microstrip color. ⑩ potassium dihydrogen phosphate: White crystal. 3. Odor identification ammonia is a liquid with strong pungent ammonia taste, ammonium bicarbonate is a particle with obvious pungent ammonia flavor, and heavy superphosphate is a sour fine powder. If calcium superphosphate has a very pungent and strange sour taste, it means that waste sulfuric acid is likely to be used in the production process. This product is very toxic and can easily damage or burn crops, especially in rice seedling fields. 4. add water to dissolve and identify 1 gram of chemical fertilizer to be tested, put it in a clean glass tube or glass or white porcelain bowl, add 10 ml distilled water or clean cold boiled water to shake fully, see how it dissolves, all dissolve is nitrogen fertilizer or potash fertilizer; what dissolves in water but has residue is calcium superphosphate; what dissolves in water without residue or residue is heavy superphosphate. Ammonium bicarbonate is soluble in water but has a strong smell of ammonia. 5. the heating identification method puts a clean piece of iron on the stove and puts the chemical fertilizer on it, and the performance of all kinds of chemical fertilizers varies greatly. Urea melts and volatilizes quickly, and a small amount of white smoke can smell ammonia; ammonium sulfate melts slowly, accompanied by the release of ammonia; ammonium nitrate burns and even explodes, accompanied by white smoke, and can smell ammonia; ammonium chloride can smell a strong pungent smell, accompanied by white smoke, melting quickly and disappearing completely, and the unmelted part is yellow in the melting process. Calcium superphosphate is unstable when heated, it can be seen that it smokes slightly and has sour taste; calcium magnesium phosphate fertilizer has no change when heated on fire; when compound fertilizer is heated on flame, white smoke can be seen, and the smell of ammonia can be smelled, which can not be completely melted. Click to get more compound fertilizer application techniques