How to distinguish between true and false chemical fertilizers

When leaving the factory, the chemical fertilizers produced by regular manufacturers are marked with the name of the fertilizer, the content of the main ingredients, the standard code name, the name of the factory and the location of the factory. There is a factory inspection certificate in it. If the packaging mark is not clear, or three no (no factory name and address, product license or registration certificate, product qualification certificate) chemical fertilizer, it is very likely to be fake and shoddy products, and the broad masses of farmers must pay attention to them. In recent years, some manufacturers and a small number of lawbreakers have disregarded the interests of the state and the broad masses of consumers and used deceptive and disguised means to manufacture and sell fake and shoddy chemical fertilizers. In this case, due to the many kinds of chemical fertilizers, different characteristics, the number of nutrients is also different, just from the appearance of observation, some chemical fertilizers are very similar, not easy to distinguish. If you incorrectly apply chemical fertilizer casually, it will cause very serious adverse consequences, so it is necessary to learn some basic knowledge of chemical fertilizer and to understand and master the nature and identification methods of chemical fertilizer.

We can identify chemical fertilizers from the following aspects:

1. From the appearance, for example, the appearance of nitrogen fertilizer is generally white or yellowish crystal, while potash fertilizer is white or flesh red crystal, which is slightly hygroscopic.

2. To distinguish from the reaction or solubility of chemical fertilizer in water.

3. identified by the burning reaction, the general chemical fertilizer has some changes through the burning, such as emitting odor and so on.

4. It is identified by the reaction of chemical fertilizer in alkali solution, such as the smell of ammonia, precipitation and so on.

In order to make the broad masses of farmers have a systematic understanding of the nature and identification methods of common chemical fertilizers and facilitate reference, the identification methods of various common fertilizers are listed as follows:

1, urea: urea appearance is white, spherical particles, total nitrogen content ≥ 46%, 0%, easy moisture absorption, moisture absorption 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 atmospheric pressure, it begins to show instability, produces condensation reaction, produces biuret and loses its fertilizer effect on crops. If you put a clean piece of iron on the stove and put the urea particles on it, you can see that the urea melts and volatilizes quickly, and there is a small amount of white smoke at the same time, and you can smell ammonia.

2, ammonium sulfate: agricultural ammonium sulfate is white or light-colored crystal, nitrogen content ≥ 20,8% (second grade). Ammonium sulfate is easy to absorb moisture and dissolve in water. The aqueous solution is acidic and reacts with alkali to release ammonia. When ammonium sulfate is heated on the fire, it melts slowly and is accompanied by the release of ammonia smell.

3. Ammonium nitrate: the appearance of ammonium nitrate is white, there are no impurities visible to the naked eye, and agricultural products are allowed to be yellowish. Total nitrogen content ≥ 34,4% (Ⅱ grade). Ammonium nitrate has strong hygroscopicity and caking, and its aqueous solution will recrystallize when the temperature changes, and it is very sensitive to heat. A large amount of ammonium nitrate is easy to decompose when heated, which can lead to explosion, accompanied by white smoke, ammonia smell can be smelled, and the aqueous solution is acidic.

4. Ammonium chloride: ammonium chloride is a white crystal, agricultural products are allowed to be yellowish, nitrogen content ≥ 25%, 39%, soluble in water, solubility in water increases significantly with the increase of temperature, and the aqueous solution is acidic. Ammonium chloride has strong water absorption and is easy to agglomerate. When a small amount of ammonium chloride is heated on the fire, a strong irritating smell can be smelled, accompanied by white smoke. Ammonium chloride will melt quickly and disappear completely, and the unmelted part can be seen to be yellow in the melting process.

5. Ammonium bicarbonate for agricultural use: the appearance is white or grayish crystal, there is ammonia smell, nitrogen content ≥ 16,80% (secondary). It has strong hygroscopicity and is soluble in water. The aqueous solution is weakly acidic. When easily identifying ammonium bicarbonate, a strong smell of ammonia can be smelled by rubbing a small number of samples with your fingers.

6, calcium superphosphate: the appearance is dark gray, grayish white, light yellow and other loose powder, there are many small pores in the block, commonly known as "honeycomb eyes". Effective phosphorus pentoxide content ≥ 12,0% (qualified product Ⅱ). Slightly sour, is a kind of acidic chemical fertilizer, sensitive to the action of alkali, easy to lose fertilizer effect. Some of them are soluble in water, and the aqueous solution is acidic. In general, the hygroscopicity is small, such as hygroscopicity occurs when the air humidity reaches more than 80%, forming a hard lump. When heating is unstable, it can be seen that it smokes slightly and has a sour taste. When the temperature is higher than 120℃, calcium dihydrogen phosphate monohydrate loses crystal water and converts into anhydrous calcium dihydrogen phosphate, and water-soluble calcium pentoxide decreases gradually. when the temperature is higher than 150℃, anhydrous calcium dihydrogen phosphate loses water and converts into calcium pyrophosphate which has no fertilizer effect on crops. no matter how high the temperature is, calcium pyrophosphate is transformed into wolfsoluble calcium metaphosphate.

7, calcium magnesium phosphate fertilizer: the appearance of gray-white, gray-green or gray-black powder, looks very fine, in the sun, you can generally see the existence of crushed, vitreous objects, sparkling. Effective phosphorus pentoxide content ≥ 12,0% (qualified product). Insoluble in water, not easy to lose, non-moisture absorption, non-toxic, non-corrosive, when heated on the fire, there is no change.

8. Compound fertilizer: the appearance should be grayish brown or grayish white granular or columnar products, no visible mechanical impurities exist. Some compound fertilizers are accompanied by the crystallization of white particles of incomplete crushed urea, or urea exists alone as whole grains in compound fertilizers. The total nutrient ≥ of ternary low concentration compound fertilizer is 25%; the total nutrient ≥ of binary low concentration compound fertilizer is 20%, in which the content of single nutrient shall not be less than 4%. Compound fertilizer is slightly hygroscopic. after moisture absorption, compound fertilizer particles are easy to crush, non-toxic, tasteless, non-corrosive, and can only partially dissolve in water. When the compound fertilizer is heated, white smoke can be seen and the smell of ammonia can be smelled, which can not be completely melted.

9. Zinc sulfate for agricultural use: needle-like crystals with a white or microstrip color. The zinc content of zinc sulfate heptahydrate should be ≥ 21,8%. Zinc sulfate is soluble in water and its aqueous solution is acidic. At present, there are many quality problems with zinc sulfate, and farmers must be cautious when buying. At present, the zinc content of "magnesium-zinc fertilizer" and "iron-zinc fertilizer" sold in large quantities in the market is only about 20% of that of real zinc fertilizer, which is a kind of zinc fertilizer with poor quality, high price and low fertilizer efficiency. Please be sure to recognize the product name when you buy it.

10. Potassium dihydrogen phosphate: White crystal in appearance. The content of potassium dihydrogen phosphate for agricultural use should be ≥ 92,0% (based on dry basis). Potassium dihydrogen phosphate is soluble in water, and the aqueous solution is acidic.