Chemical fertilizers produced by regular manufacturers are marked with the name of the fertilizer, the content of the main ingredients, the standard code, the name of the factory, and the address of the factory. It is accompanied by a factory inspection certificate. If the packaging mark is not clear, or three no (no factory name, product license or registration certificate, product certificate) fertilizer, it is very likely to be counterfeit and shoddy products, the majority of farmers must pay attention.
In recent years, some manufacturers and a few lawless elements have ignored the interests of the state and the vast number of consumers, and used the means of deceitful camouflage to manufacture and sell fake deterioration fertilizer. In this case, because there are many types of fertilizers, their characteristics are different, and the number of nutrients contained is different. From the outside, some fertilizers are very similar and difficult to distinguish. If the fertilizer is applied erroneously, it will cause very serious adverse consequences. Therefore, it is necessary to learn some basic knowledge of chemical fertilizers, understand and master the nature and identification methods of chemical fertilizers.
We can identify the fertilizer from the following aspects: 1. From the appearance to identify, such as the appearance of nitrogen fertilizer is generally white or light yellow crystal, potassium fertilizer is white or meat red crystal, are slightly hygroscopic; 2. from fertilizer Identification by reaction or solubility in water; 3. Identification by burning reaction, general chemical fertilizer has some changes through burning, such as odor emission; 4. Identification by the phenomenon of chemical fertilizer reaction in alkali solution, such as releasing ammonia smell, appearing Precipitation, etc.
In order to enable the masses of farmers to have a systematic understanding of the nature and identification methods of common fertilizers and easy access, the identification methods of various common fertilizers are listed below:
1. Urea urea appearance is white, spherical particles, total nitrogen content ≥ 46.0%, easy to absorb moisture, hygroscopicity between ammonium sulfate and ammonium nitrate. Urea is easily soluble in water and liquid ammonia. When pure urea is heated to near the melting point under normal pressure, it begins to show instability, produces a condensation reaction, and produces biuret, which loses fertilizer effect on the crop. If you put a clean piece of iron on the stove and put the urea granules on it, it can be seen that the urea melts and volatilizes quickly, and a small amount of white smoke is emitted, which can smell ammonia.
2. Ammonium sulphate Agricultural ammonium sulphate is white or light colored crystal, nitrogen content ≥ 20.8% (second grade). Ammonium sulfate is easy to absorb moisture, soluble in water, and the aqueous solution is acidic. It reacts with alkali to release ammonia gas. When ammonium sulfate is heated on the fire, it can be slowly melted and accompanied by ammonia release.
3. Ammonium nitrate Ammonium nitrate has a white appearance and no visible impurities, and agricultural products are allowed to have a yellowish color. The total nitrogen content is ≥34.4% (Level II). Ammonium nitrate has strong hygroscopicity and agglomeration. When the temperature of the aqueous solution changes, recrystallization will occur, which is very sensitive to the action of heat. A large amount of ammonium nitrate is easily decomposed by heat, and combustion can occur, resulting in an explosion. It is accompanied by white smoke, which smells ammonia and the aqueous solution is acidic.
4. Ammonium chloride ammonium chloride is white crystal, the agricultural product is allowed to have a yellowish color, the nitrogen content is ≥25.39%, and it is easily soluble in water. The solubility in water increases remarkably with the increase of temperature, and the aqueous solution is acidic. Ammonium chloride has strong water absorption and easy to agglomerate. A small amount of ammonium chloride is heated on the fire to smell a strong irritating odor, accompanied by white smoke. The ammonium chloride will melt rapidly and disappear completely. The unmelted portion was yellow during the process.
5. Agricultural ammonium bicarbonate appearance is white or slightly gray crystal, with ammonia smell, nitrogen content ≥ 16.80% (secondary). It is highly hygroscopic, soluble in water, and the aqueous solution is weakly acidic. When you easily identify ammonium bicarbonate, you can use a finger to take a small amount of sample for rubbing, you can smell a strong ammonia smell.
6. The appearance of superphosphate is dark gray, grayish white, light yellow and other loose powder. There are many small pores in the block, commonly known as "honeycomb eye". The effective phosphorus pentoxide content is ≥12.0% (qualified product II). Slightly sour, it is an acidic chemical fertilizer that is sensitive to the action of alkali and easily loses its fertilizer effect. Some of them are soluble in water and the aqueous solution is acidic. Under normal circumstances, the hygroscopicity is small, such as moisture absorption when the air humidity reaches 80% or more, forming a hard block. It is unstable when heated, and it can be seen to be slightly smoked and has a sour taste. When the temperature is higher than 120 °C, the calcium dihydrogen phosphate monohydrate loses the crystal water and turns into anhydrous calcium dihydrogen phosphate, and the water-soluble phosphorus pentoxide gradually decreases. When the temperature is higher than 150 °C, the anhydrous calcium dihydrogen phosphate loses water and is converted into calcium pyrophosphate which has no fertilizer effect on the crop. The temperature is higher, and the calcium pyrophosphate is converted into the bismuth-soluble calcium metaphosphate.
7. The appearance of calcium magnesium phosphate fertilizer is grayish white, grayish green or grayish black powder, which looks very fine. Under the illumination of sunlight, it is generally seen that pulverized, vitreous-like objects exist and sparkle. Effective phosphorus pentoxide content ≥ 12.0% (qualified product). Insoluble in water, not easy to lose, no moisture absorption, no toxicity, no corrosive, no change when heating on fire.
8. The appearance of the compound fertilizer should be gray-brown or off-white granular or columnar product, and no visible mechanical impurities exist. Some of the compound fertilizers are accompanied by crystallization of white particles of incompletely pulverized urea, or in the compound fertilizer, urea is present as a single crystal. The total nutrient of ternary low-concentration compound fertilizer is ≥25%; the total nutrient of binary low-concentration compound fertilizer is ≥20%, and the single nutrient content should not be lower than 4%. The compound fertilizer is slightly hygroscopic. After the moisture absorption, the compound fertilizer particles are easily pulverized, non-toxic, odorless, non-corrosive, and only partially soluble in water. When the compound fertilizer is heated, white smoke is observed, and the smell of ammonia can be smelled, and it cannot be completely melted.
9. The zinc sulfate for agricultural use has white or micro-colored needle crystals. The zinc content of zinc sulfate heptahydrate should be ≥21.8%. Zinc sulfate is readily soluble in water and its aqueous solution is acidic. At present, the quality of zinc sulfate is very problematic, and farmers must be cautious when purchasing. At present, “magnesium-zinc fertilizer†and “iron-zinc fertilizer†are sold in large quantities on the market. The zinc content is only about 20% of the true zinc fertilizer. It is a kind of zinc fertilizer with poor quality, high price and low fertilizer efficiency. Please buy when you buy it. Be aware of the product name.
10. Potassium dihydrogen phosphate appears as white crystals. The content of potassium dihydrogen phosphate for agriculture should be ≥92.0% (on a dry basis). Potassium dihydrogen phosphate is easily soluble in water and the aqueous solution is acidic.
At present, the packaging mark of potassium dihydrogen phosphate is very chaotic. Some manufacturers use deceptive methods to premise potassium dihydrogen phosphate with potassium dihydrogen phosphate or mixed fertilizer. The method is as follows: (1) write the words potassium dihydrogen phosphate very large The word "ammonium" is written very small: (2) the small word "high-efficiency compound fertilizer I (II) type" is marked on the upper right side of the package, and the potassium dihydrogen phosphate is marked in large characters in the middle; (3) potassium dihydrogen phosphate type II. In all three cases, the description indicates that the fertilizer consists of nitrogen, phosphorus and potassium. It is well known that potassium dihydrogen phosphate contains only phosphorus and potassium, and does not contain nitrogen. In the national standard, potassium dihydrogen phosphate does not have the type I or II. All of the above cases are deceptive behaviors. I hope that farmers friends should be careful when purchasing fertilizers, beware of being fooled!
Farmers should pay attention to the purchase of fertilizer: one chooses the famous brand fertilizer of Dachang; the second looks at the "three certificates", that is, the production license, registration certificate and standard certificate number; three looks at the nutrient content and the test list; four sees whether the packaging is regular, generally 40 kg 50 kg loading; five look at the factory certificate and instructions for use; six to the credit card and invoice, the use of rights in the future; seven look at the appearance of quality, uniform particles, smooth surface, good hardness, no agglomeration, less precipitation after dissolution.
Huaxian County Agricultural Products Inspection and Testing Center Chang Bili
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