Since the late 80-ies in Ukraine, the mass production of a new liquid nitrogen fertilizer - a mixture of solutions of carbamide and ammonium nitrate - UAN.
Mineral fertilizer UAN contains in its composition three forms of nitrogen: nitrate and ammonium from ammonium nitrate, amide from carbamide. Other nitrogen fertilizers - ammonia, ammonium sulfate, carbamide, ammonium nitrate - contain a maximum of two.
Fertilizer UAN has a number of advantages over solid nitrogen fertilizers. With the use of the UAN, complete mechanization of the storage of the UAN, transportation of the UAN and the introduction of UAN into the soil is ensured, nutrient losses are reduced and environmental pollution is reduced, and efficiency is improved due to a more even application of fertilizers. When applying fertilizer UAN, in comparison with ammonia water and liquid ammonia, the working conditions of machine operators are improved and safety is simplified. The crystallization temperature of the UAN solutions increases with an increase in the percentage of nitrogen from -18°C for UAN-28 to -2°C for UAN-32. Fertilizer UAN-32 contains in its composition a mass fraction of ammonium nitrate 43-48%, the mass share of carbamide - 33-37%. The freezing temperature of solutions of all UAN grades is minus 26°С. The formation of crystals and the short-term freezing of UAN solutions from UAN-28 to UAN-32 in storage tanks are not a big danger, as with increasing temperature the crystals dissolve and UAN fertilizers completely restore their properties . The viscosity of solutions of UAN at a temperature of 20°C is, on the average, equal to 5 mPa, which is several times lower than the viscosity of the Liquid complex fertilizers (LCF) 10-34-0, the pH of the solutions is 7-8. Solution of UAN do not burn and do not explode.
Buy UAN can and in the off-season - the warranty period of storage of UAN without changing the quality indicators is 6 months. Adding UAN as fertilizer inhibitors to ammonium phosphate corrosion significantly reduces corrosion activity. For storing solutions you can use storage tanks designed for ammonia water and LCF 10-34-0. When filling containers intended for ammonia water, it is necessary to take into account that the density of UAN is on the average 1/3 g / cu. See Filling tanks with fertilizer UAN more than 80% of the volume is not recommended, as exceeding this level can lead to deformation of capacity and loss of fertilizers. Physico-chemical and corrosion properties of fertilizer UAN, as well as structural, agrotechnical and operational-technological indicators of machines intended for use in liquid fertilizers, completely allow using them in the application of UAN. When using retrofitted equipment, it is necessary to replace non-ferrous metal parts with polyvinyl chloride or fiberglass ones, and use laminated rubber TMKSCH on the basis of styrene rubber (GOST 7338-77) as a gasket material. As flexible pipelines, rubber pressure sleeves with textile frame of class (P) rubber (GOST 18698-79) can be used. For transportation and application of UAN, serial machines are used - fertilizers with liquid fertilizers PGU-2, 5, PGU-5, PGU-9, sprayers POM-630 and OP-2000-2-01, automobile semi-trailers GKB-9653, GKB-9677, PPZU-9370, tractor refuellers OZTP-9625 and OZTP-9654, as well as converted tanks RZhT-8 with the bar Asha-15, ARUP-8, RZhT-4, KhTS-100, 27, etc. The density of the UAN depends to a large extent on Ambient temperature, therefore, in determining the dose of this fertilizer and for each particular UANe it is necessary to check its consumption in 1 s.
In addition to ground-based equipment, for non-root fertilizing agricultural crops with UAN fertilizers, it is possible to use aviation equipment. For this, the spray equipment of the AN-2 airplane with the device OZH-2 is suitable. The spray boom is equipped with serial slit sprayers. You can use UAN and with irrigation water. The experience of using UAN solutions showed that, with the main application, they are highly effective fertilizers of equivalent ammonium nitrate, carbamide and liquid ammonia in the effect on the yield of agricultural crops.
It is also effective to use UAN solutions for foliar feeding of agricultural crops. The first spring top feeding of winter crops should be carried out after the snow retreats when plant vegetation renews, during tillering, spending 30-60 kg of nitrogen per 1 ha. Further increase in the dose of nitrogen in the feeding of UAN in the tillering phase is undesirable because of the possibility of forming an increased number of unproductive stems. In addition, a high concentration of salts on the leaf surface can cause severe burns to plants, to which plants are particularly sensitive in the phase of entering the tube and beginning the ear. Therefore, a single dose of nitrogen at this time should not exceed 20-30 kg per 1 ha. Doses of nitrogen for top feeding are set taking into account soil, leaf and tissue diagnostics, in connection with which the number of fertilizing can be changed, but the dose should not exceed the allowable. UAN fertilizers can be added, diluted and not diluted with water. It depends on the technical capabilities of the units. When diluting, the working solution consumption per hectare should be 100-300 liters.
The best time for foliar fertilizing with fertilizers UAN - morning (in the absence of dew) and evening hours. In the cool and cloudy weather, this work can be done during the day. Do not feed plants with mineral fertilizers UAN at a temperature above 20 ° C, low relative humidity, on a sunny day, as in these UANes, burns of the leaf surface of plants. The young leaves of plants are most prone to burns. In all phases of plant development, fertilizer UAN even with a dose of 10 kg nitrogen per 1 ha causes some plant burns, but they do not lead to a decrease in yield. Solutions UAN can be used for the preparation of double and triple liquid fertilizer mixtures. The technique of preparing nitrogen-phosphoric solutions is simple, since UAN solutions can be mixed with 10-34-0 LCF in any ratio directly in the tanks of the injection machines. When obtaining triple balanced nutrient solutions, the total concentration of nutrients does not exceed 30%. To increase the concentration in the liquid fertilizer mixture, it is necessary to introduce stabilizers that prevent the rapid sedimentation of the solid phase. Preparation of liquid fertilizer mixtures (solutions and suspensions) is mainly reduced to successive dosing, mixing or grinding of components. In order to accelerate the dissolution of solid initial components, it is necessary to heat the water to a temperature of 70-80 ° C. The starting components are HCFC 10-34-0, UAN, urea, potassium chloride, water. To stabilize suspensions, bentonite clay (clay powder) phosphogypsum or superphosphate is used, which is added in an amount of 1-3% by weight of the slurry. In the preparation of solutions, the components are mixed until completely dissolved, in the preparation of suspensions, a stable mixture must be created that does not settle for several days. Triple solutions, as well as suspended fertilizer mixtures are prepared only on special mixing plants. The choice of a specific technological scheme of the UAN application depends on the distance of the UAN transportation, the availability and location of warehouses, vehicles, road conditions, etc. Fertilizer UAN is used for the following main technological schemes.
The first scheme. Plant - vehicle - unit for making. This circuit is recommended for use within a radius of 40-50 km from the plant.
The second scheme. Plant - vehicle - deep store - vehicle - unit for making. The scheme is used at the following distances: from the plant to the deep composition of 40-50 km and from the deep store to the field of 20 km.
The third scheme. Plant - railway tank - pre-rail warehouse - vehicle - unit for making. The scheme is applied at the following distances: from the factory to the railroad track the composition is more than 100 km and from the near-track warehouse to the field no more than 40-50 km.
The fourth scheme. Plant - railway tank - pre-rail warehouse-vehicle - deep store - vehicle - unit for making. The scheme is used for the following distances: from the factory to the railroad track, the composition is more than 100 km, from the near-track warehouse to the deep storehouse and from the deep warehouse to the field of 20 km.
One of the good reasons to buy UAN is the higher economic efficiency of UAN solutions compared to solid nitrogen fertilizers, which is explained by the increase in labor productivity and the low cost of nitrogen contained in the fertilizer. Calculations showed that application of UAN fertilizer in comparison with ammonium nitrate allows to reduce operating costs by 9%, capital costs by 30% for each ton of nitrogen, and application of liquid fertilizer mixtures - by 22.34 and 21% respectively, labor costs by 34% Compared with the separate application of the same amount of nutrients in the form of solid fertilizers.
The price of the UAN, as well as other mineral fertilizers, is determined by market demand and subject to seasonal fluctuations.
It is forbidden to load capacity more than the allowable norm (95% of their volume).
It is forbidden to graze animals on sites treated with UAN for 5 days, as well as finding them in the sprinkling zone.
Intensive technology of growing cereal crops suggests extensive use of fertilizers, plant protection products against diseases and growth regulators. The use of chemicalization means is growing every year, so the development and introduction of techniques for the most economical use of them for agricultural crops is becoming increasingly important. As is well known, one of the bottlenecks in the cultivation of crops by intensive technologies is the separate application of fertilizers, retardants, herbicides and fungicides, which necessitates multiple passes on the sowing of machinery, hence additional costs are required. The introduction of techniques that allow to reduce operations for the introduction of chemicals for the cultivation of cereals, as well as other crops, can reduce energy costs, manpower, improve the quality of work. In addition, due to the limited interphase period of plants, lack of machinery and labor resources, it is almost impossible to meet the optimal terms for the introduction of nitrogen fertilizers, growth regulators and plant protection products against diseases. A method is proposed that allows to combine the introduction of growth regulators with the second nitrogen fertilizing of crops with carbamide. However, the preparation of tank mixtures of urea and retardants in production conditions is difficult to implement because of the lack of technical means. Increasing the production and use of liquid nitrogen fertilizer - carbamide-ammonium UAN mixture greatly simplifies the technology of mixing liquid fats. In countries of intensive agriculture, the production and use of nitrogen-containing solutions is constantly increasing. The experience of using nitrogen fertilizers such as UAN shows that their effectiveness is the same as for other types of liquid and solid nitrogen fertilizers.
