Nitrate nitrogen and ammonium nitrogen can be directly absorbed and utilized by plants, and their behaviors and metabolism after being applied to soil are different, so they have their own advantages and disadvantages as plant nitrogen sources.
agrochemical
The properties of fertilizer applied to soil and interacting with soil and plants are often called agrochemical properties. First of all, nitrate is negatively charged, so it is not easy to be adsorbed by soil colloid with negative charge. Ammonium ion is positively charged, which is easy to be absorbed by soil daughter-in-law. It can not only be adsorbed on the soil surface, but also enter the crystals of clay minerals to become fixed ammonium ion. Therefore, nitrate nitrogen mainly exists in soil solution, which is highly mobile, easily absorbed and utilized by plants, and easily lost with rain. Aetna, however, is mainly adsorbed and fixed on the surface of soil colloid and colloid lattice, which is less mobile and easier to be "enclosed" by soil. Secondly, different forms of nitrogen will be transformed into each other in soil. Under suitable conditions of temperature, moisture and ventilation, urea is hydrolyzed to ammonium nitrogen and ammonium nitrogen is oxidized to nitrate nitrogen under the action of soil microorganisms and enzymes. Therefore, the transformation of urea and ammonium nitrogen is slow in early spring and low temperature season, and fast in summer and high temperature season. Nitrate nitrogen is often more than ammonium nitrogen in dryland soil, but little in paddy soil. Third, the soil moisture is too high. Under the condition of poor ventilation and fresh organic matter, nitrate nitrogen can be reduced to nitrous oxide, nitric oxide and nitrogen under the action of microorganisms, and this denitrification is one of the main ways of nitrate nitrogen loss. The main way of nitrate nitrogen loss from soil is ammonia volatilization.
Therefore, nitrate nitrogen fertilizer is suitable for cold regions and seasons. It can be applied in dry land by stages, and its fertilizer efficiency is fast and obvious, but it is not suitable for high temperature and rainy paddy fields. Ammonium nitrogen fertilizer is suitable for paddy field and dry land, but it is suitable for soil surface or paddy field, and the loss of ammonia volatilization is great.
A simple method to identify the authenticity of fertilizer can be summarized as five words "look, touch, smell, burn and wet".
First, look:
(1) Fertilizer packaging. The fertilizer produced by regular manufacturers has a standard and strong outer packaging. Generally, the production license, implementation standard, registration license, trademark, product name, nutrient content (grade), net weight, factory name, address, etc. are indicated; The packaging of fake and shoddy fertilizers is generally rough, the information on the packaging bag is unclear, the quality is poor, and it is easy to leak.
(2) the granularity (or crystalline state) of the fertilizer. Nitrogen fertilizer (except lime nitrogen) and potassium fertilizer are mostly crystals; Phosphate fertilizer is mostly amorphous in bulk or powder, such as calcium magnesium phosphate in powder, while calcium superphosphate is mostly porous and bulk: high-quality compound fertilizer has uniform particle size and specific gravity, smooth surface and is not easy to absorb moisture and agglomerate. Such as: Russian three-element compound fertilizer (16*16*16) and American diammonium. On the contrary, fake and inferior fertilizers are uneven, rough, humid and easy to agglomerate.
(3) the color of the fertilizer. Different fertilizers have their own unique colors. Nitrogen fertilizers are almost all white except lime nitrogen, and some are slightly yellowish brown or light blue (except those with other ingredients). Potassium fertilizer is white or reddish, such as potassium dihydrogen phosphate is white; Phosphate fertilizer is mostly dark gray, such as calcium superphosphate, calcium magnesium phosphate is gray, diammonium phosphate is brown, etc., and farmers can make a general distinction according to this.
second, touch: put the fertilizer in the palm of your hand, hold it hard or press it to turn, and judge the fertilizer according to the feel. Using this method, it is more effective to distinguish diammonium in the United States. If you grab a handful of fertilizer and hold it hard for several times, it will be genuine if it feels "oily", while if it is as dry as before, it will probably be counterfeit with flip-chip compound fertilizer. In addition, the phosphate fertilizer that is impersonated by fly ash can also be judged simply by "feeling".
3. Smell: Simply judge by the special smell of fertilizer. For example, ammonium bicarbonate has a strong ammonia odor; Ammonium sulfate is slightly sour; Calcium superphosphate has a sour taste. The smell of fake and shoddy fertilizers is not obvious.
fourthly, burning: the fertilizer sample is heated or burned, and the fertilizer can be identified from the flame color, melting condition, smoke smell and residue condition.
(1) Ammonium bicarbonate, a nitrogen fertilizer, decomposes directly, producing a large amount of white smoke, with strong ammonia smell and no residue; Ammonium chloride, directly decomposed or sublimated, produces a lot of white smoke, which has a strong ammonia taste and sour taste, and has no residue; Urea can melt quickly, emit white smoke, and burn in a charcoal fire, or when a glass sheet is exposed to white smoke, a layer of white crystals can be seen on the glass sheet; Ammonium nitrate, which does not burn but melts and boils, emits smoke with ammonia smell.
(2) Phosphate, calcium superphosphate, calcium magnesium phosphate and phosphate rock powder have no change on red charcoal; Bone meal quickly turns black and gives off a burnt smell.
(3) Potassium fertilizers, such as potassium sulfate, potassium chloride, potassium magnesium sulfate, etc., did not change on red charcoal, making a crackling sound.
(4) The combustion of compound fertilizer is closely related to its constituent raw materials. When there is ammonia nitrogen or amide nitrogen in its raw materials, it will give off a strong ammonia smell and have a lot of residues.
From the shape and color identification: 1. Urea: white or light yellow, with granular, needle-like or prismatic crystals. 2. Ammonium sulfate: white crystal. 3. Ammonium bicarbonate: white or other variegated powder or granular crystals, and some manufacturers produce large-particle oblate ammonium bicarbonate. 4. Ammonium chloride: white or light yellow crystal. 5. Ammonium nitrate: white powdery crystals or white or light yellow spherical city particles. 6. Ammonia water: colorless or dark liquid. 7. Lime nitrogen: grayish black powder. 8. Calcium superphosphate: grayish white or light skin powder. 9. Calcium superphosphate: dark gray, grayish white particles or powder. 1. Calcium magnesium phosphate fertilizer: it is grayish brown or dark green powder. 11. Calcium, magnesium, phosphorus and potassium fertilizer: grayish brown or dark green powder. 12. Phosphate rock powder: it is gray, brown or yellow drizzle powder. 13. Nitrophosphate: grayish white particles. 14. Potassium sulfate; It is white crystal or powder. 15. Potassium chloride: white or reddish particles. 16. Monoammonium phosphate: it is grayish white or dark gray particles. 17. Diammonium phosphate: white or light yellow particles.
it's hard to say the difference between domestic fertilizer and imported fertilizer. Foreign fertilizers are made of raw materials on Mars? Farmers are superstitious about imported chemical fertilizers and other things abroad. Of course, there are many and miscellaneous compound fertilizers in China, many of which are of poor quality and insufficient content.
the content of imported fertilizers is usually high, such as 19-19-19. However, farmers generally use it according to the previous application amount, so it is more effective. In fact, the fertilizers produced by many regular manufacturers in China are still reliable. The price of imported fertilizers is relatively high, and more and more farmers are using domestic fertilizers. They have won the trust of farmers in image and use effect (of course, manufacturers have also strengthened their publicity in recent years).