CALCIUM AMMONIUM NITRATE-A NEW TYPE OF HIGH-EFFICIENCY COMPOUND FERTILIZER

Calcium ammonium nitrate is a kind of compound fertilizer with the chemical formula of 5ca (NO3) 2 nh4no3 10h20. It is white and round granulated, very soluble in water, and has strong hygroscopicity, caking and flammability. It is a new type of high-efficiency compound fertilizer containing nitrogen and available calcium, with the characteristics of rapid nitrogen supplement, in which calcium is added, and the nutrients are more comprehensive than ammonium nitrate, which can be directly absorbed by plants. This product is a neutral fertilizer with low physiological acidity and can improve acidic soil. After being applied to the soil, the pH value is low, which will not cause soil hardening and make the soil loose. At the same time, it can reduce the concentration of active aluminum and the fixation of active phosphorus, and the water-soluble calcium provided can improve the resistance of plants to diseases. Can promote the activities of beneficial microorganisms in the soil. When planting cash crops, flowers, fruits and vegetables, the fertilizer can prolong the flowering period, promote the normal growth of roots, stems and leaves, ensure the bright color of fruits and increase the hardness of fruits.

Characteristics of ammonium nitrate and necessity of modification Fertilizer grade ammonium nitrate contains 33% ~ 34% nitrogen, which is a common nitrogen fertilizer variety in Europe, North America and some temperate countries. Judging from the demand for fertilizer from crop ammonia nutrition, ammonium nitrate has the advantages of fast fertilizer efficiency and can supply ammonium and nitrate nitrogen sources at the same time, which is undoubtedly beneficial to the growth of many crops. A large number of application facts have shown that except for a few crops grown in paddy fields such as rice, most crops, especially cash crops such as fruit trees, melons, vegetables and tobacco in dry farming, like ammonium nitrate. However, according to the chemical characteristics of fertilizer, ammonium nitrate is a kind of nitrogen fertilizer which is very soluble in water and has strong hygroscopicity, caking and flammability. These characteristics not only bring great difficulties to agricultural use, but also determine that improper management of ammonium nitrate in storage and transportation will cause fire or explosion. In fact, many countries in the world, including China, have had serious accidents caused by ammonium nitrate. Therefore, ammonium nitrate was forbidden to enter the fertilizer market in China.

In recent years, with the expansion of irrigation and fertilization area, the demand for agricultural ammonium nitrate has increased. Some production enterprises aim at improving their performance and quality, and modified ammonium nitrate products appear on the market. In the way of technical transformation, the following three methods are adopted: it produces granular ammonium nitrate, and before granulation, it adds stabilizers with low hygroscopicity or insoluble inert substances, such as bone meal, phosphate rock powder, dolomite, Gao Cen soil and diatoms; Secondly, a film-forming agent is used to coat a protective film on the surface of ammonium nitrate particles to isolate air. Commonly used film-forming agents include vegetable oil, mineral oil, resin and paraffin wax. Thirdly, the composition of ammonium nitrate is appropriately changed to produce calcium ammonium nitrate, ammonium sulfate and ammonium phosphate. Earlier, some European countries explicitly prohibited the application of single ammonium nitrate in agricultural applications, and some production enterprises added ammonium sulfate, magnesium nitrate, potassium chloride and calcium nitrate to ammonium nitrate to make compound fertilizers. All the above technical approaches can improve the unhealthy state of ammonium nitrate.

Calcium ammonium nitrate is a commonly used modified product of ammonium nitrate at home and abroad. Characteristics and application of calcium ammonium nitrate (molecular formula NH4NO3+CaC03) is made of molten ammonium nitrate and limestone powder in a ratio of 60:40, and it is also made of dolomite (a mixture of calcium carbonate and magnesium carbonate) and ammonium nitrate. It contains about 20% nitrogen. As for the detailed composition, the products produced by different manufacturers will be somewhat different. Now, for example, the Shima brand calcium ammonium nitrate of Dekalium Group Company contains 27% ammonia (N), including 13.5% ammonium, 13.5% nitrate and 12% calcium (CA0), with an average particle size of 3.0~3.6mm and a capacity of about 1.0 tons/m3. The appearance color of calcium ammonium nitrate is generally gray or grayish brown particles, but also green. Among them, ammonium nitrogen and nitrate ammonia each account for half, and the nitrogen content is much less than the original ammonium nitrate. However, it has small hygroscopicity, not easy to agglomerate, good dispersibility and good physical properties.

Calcium ammonium nitrate contains a lot of calcium carbonate, which has good effect and effect as topdressing in acidic soil. When applied in paddy field, its fertilizer efficiency is slightly lower than that of ammonium sulfate with equal nitrogen content, but it is similar to that of ammonium sulfate when applied early. The cost of nitrogen in calcium ammonium nitrate is higher than that of ammonia in ordinary ammonium nitrate. As a low-concentration fertilizer, calcium ammonium nitrate is a physiologically neutral fertilizer, and long-term application plays a good role in soil properties. It can be used as topdressing on cereal crops.

Nitrogen in calcium ammonium nitrate particles can be released quickly, while lime dissolves slowly. The field test results in acid soil show that the agricultural effect of calcium ammonium nitrate is good and the total yield level can be improved.