Differences and characteristics of ammonium nitrogen, nitrate nitrogen and amide nitrogen

Nitrogen is divided into ammonium nitrogen, nitrate nitrogen, amide nitrogen, so what are the differences between these kinds of nitrogen? How about the absorption rate and duration of efficacy? What is the difference in safety?
Now a brief description, to achieve a basic understanding of the use of fertilisers with a little help.

Ⅰ. Concept and distinction
[Ammonium nitrogen] Ammonium nitrogen includes ammonium bicarbonate, ammonium sulphate, ammonium chloride, ammonia and so on.
The characteristics of ammonium nitrogen:
1, Ammonium nitrogen is positively charged, and the soil is negatively charged, easy to be adsorbed by the soil colloid is easy to be adsorbed, so that it is not easy to be lost (such as rain, diffuse irrigation, etc.).
2, Plant absorption of ammonium nitrogen is divided into 2 ways: ① directly in the form of ammonium ions absorbed by the plant; ② oxidation into nitrate, in the form of nitrate absorbed by the plant.
3, In the alkaline environment, ammonia is easy to volatile loss.
4, High concentration of ammonium nitrogen is toxic to crops.
5, Crops absorbing excessive ammonium nitrogen has a certain inhibitory effect on the absorption of calcium, magnesium and potassium.
[Nitrate Nitrogen]Nitrate nitrogen includes sodium nitrate, calcium nitrate, ammonium nitrate and so on.
The characteristics of nitrate nitrogen:
1, Easily soluble in water, moving faster in the soil.
2, NO3-absorption is the main absorption, the crop is easy to absorb nitrate.
3, Nitrate material on crop absorption of calcium, magnesium, potassium and other nutrients without inhibition.
4, Nitrate is negatively charged anion, can not be adsorbed by the soil colloid, easy to lose with water.
5, Nitrate is easily reduced to gas state (NO, N2O, N2) through denitrification, and escaped from the soil.
[Amide nitrogen] Amide nitrogen - urea [CO(NH2)2], containing 46.7% nitrogen, is the highest nitrogen content in solid nitrogen material.
Excessive temperatures in pelleting will produce diurea (also known as biuret), which has an inhibitory effect on crops. When the content of diurea is more than 1%, it can not be used as seed fertiliser, seedling fertiliser and foliar fertiliser, and the content of urea in other application periods should not be too much or too concentrated .
Amide nitrogen belongs to organic nitrogen fertiliser, after the soil urease, hydrolysis into ammonium carbonate or ammonium bicarbonate to be absorbed by the crop, before hydrolysis, the soil in the form of molecules, only 20% of the adsorption by the soil, pay attention to the deep burial.
Ⅱ.Comparison of fertiliser efficiency, shelf life and safety:
Ammonium nitrogen, nitrate nitrogen and amide nitrogen have their own characteristics and advantages, in terms of fertiliser efficiency (crop absorption rate), nitrate nitrogen > ammonium nitrogen > amide nitrogen; excluding ammonia volatilisation, fertiliser efficacy persistence (soil adsorption) time: ammonium nitrogen > amide nitrogen > nitrate nitrogen; safety: nitrate nitrogen > ammonium nitrogen > amide nitrogen.
Precautions: ① Under greenhouse environment, the use of ammonium nitrogen should be reduced appropriately. Greenhouse sealed environment, will increase the chance of ammonia damage, and vegetables are nitrogen-loving crops; ② nitrate nitrogen is mostly applied to dry land, paddy fields should reduce the use of nitrate nitrogen fertiliser. Because nitrate nitrogen in the soil is difficult to adsorb and fix, too much loss, and long-term use will make the crop produce carcinogenic nitrite.