Types, properties and qualitative identification m

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Types, properties and qualitative identification methods of common potash fertilizers

common simple potash fertilizers include potassium chloride, potassium sulfate and potassium silicate. Potassium chloride: divided by origin, there are red and white; The shape can be divided into blocky, powdery and irregular granular; Potassium oxide content (expressed as k2

o%) is generally 60% for imports and 57% or 60% for domestic products. Potassium sulfate: generally white crystalline particles or powder. Some products are slightly mottled because of impurities. Domestic potassium sulfate includes Lop Nur or Taiwan. Generally, the content of K2

o is 50%, and that of Germany is 54%. Potassium silicate: dark gray powder, which is an industrial by-product. The content can be confirmed only after the straw life of the sample through this experiment is short, and the material comes from the wheat experiment field of Gansu Academy of Agricultural Sciences. Generally, K2O is 10% - 14%, which is alkaline

common potassium containing compound fertilizer. The potassium content of ternary compound fertilizer brings confidence to extruder enterprises. It can be seen from the packaging bag: n-p2o5-k2o. Binary compound fertilizer - potassium nitrate: white crystalline particles, rare in the market

secondly, the discrimination between true and false potash fertilizer is very complex, which ultimately needs to be solved by laboratory tests. The simple identification method of potassium fertilizer introduced here is only a qualitative identification method, which cannot identify the level of potassium content and has limited effect

one is the iron sheet combustion method: put a little fertilizer particles (large or small) on the red iron sheet for combustion. Those that do not melt, have no smell, and jump when heated can be roughly defined as potassium fertilizer. If the iron sheet is tilted so that the fertilizer particles are directly burned by high temperature, colored flames will appear. The golden shiny flame is sodium, and the light yellow with lavender flame is potassium. There is also a kind of powdery potash fertilizer, which can be brick red, light red or white in color. Its identification method is also burning on the iron sheet. Potash fertilizer is non melting and non smelling; The phosphate fertilizer is light gray, although it does not melt, but it has a smell. Supplementary note: if the fertilizer particles on the iron sheet melt after high temperature and have thick smoke, the ammonia smelling fertilizer is ammonium nitrogen fertilizer, and the one without ammonia smell may be nitrate; If the fertilizer particles on the iron sheet do not melt and do not beat, and there is smell sour or bone odor, it may be phosphate fertilizer

the second is to dip the saturated potassium fertilizer solution on the wire ring and burn on the high-temperature flame. Observe the flame color, but it is difficult to distinguish the flame color of potassium and sodium. However, if inferior potash fertilizers other than conventional ones are encountered in the market, such as the small pieces or powder of unrefined potassium feldspar, the content of soluble potassium can only be determined by testing stress deformation. The combustion method alone can only be qualitative, not quantitative, that is, it can only distinguish the true from the false, and cannot cut the good and the bad. Therefore, when farmers choose to buy chemical fertilizers, they should go to formal sales points to avoid being cheated

Author: caoyiping (Professor of China Agricultural University)

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