UAN-32 is a mixture of aqueous solutions of ammonium nitrate and carbamide (in the ratio of 35.4% of carbamide, 44.3% of saltpeter, 19.4% of water, 0.5% of ammonia water). Density of liquid fertilizer to 1.34 kg/m3.
Thus, UAN provides prolonged nutrition of plants with nitrogen. In view of the absence of free ammonia in the UAN, it does not evaporate into the atmosphere when applied, but the presence of an ammonium form still makes the minimum embedding desirable, especially in high temperature and no precipitation after application.
The cost price of nitrogen in the UAN is the lowest, since nitrogen losses when applying UAN do not exceed 10% of total nitrogen, while when applying granular nitrogen fertilizers they reach 30-40%.
The introduction of UAN as liquid fertilizers is much more evenly than solid, granular.
The application of UAN is well combined with the use of pesticides in one tank mix. This allows to reduce quantity of operations for caring for crops.
It is expedient to use for fractional fertilizing of vegetative plants. At the same time, both root and foliar top feeding take place. Depending on the phases of growing of cultivated plants and the equipment used, UAN is diluted with water in the required ratio or is not diluted.
The application of UAN is well combined with microelements.
The need for foliar feeding is caused by the following factors: stressful situations (low temperatures, frosts, lack of moisture, etc.), slowing down the intensity of assimilation of nutrients by the root system, which slows down the growth and development rates. In conditions of low temperatures or lack of moisture in the soil, the absorption of nutrients significantly slows down. Often critical periods regarding the lack of macro- and microelements in cereals occur in the phase of exit into the tube - ear. Due to the intensive, rapid growth of the vegetative mass, the reserves of readily accessible nutrients from the soil are exhausted or their assimilation "does not keep pace with the rates of plant growth." In this situation, foliar (leaf) fertilizing with UAN is required.
In case of using UAN, the degree (percentage) and rate of assimilation of nutrients from fertilizer UAN through the leaf surface is much higher than when assimilated from fertilizers introduced into the soil. For these purposes, a solution of UAN dissolved in water is best suited. The amide form of nitrogen quickly penetrates through the leaf surface of cereal grains and other crops.
Feeding through the leaves is advisable to combine with the introduction of microelements and (or) plant protection products.
UAN is, first of all, a very flexible additional tool for feeding crops in a highly efficient production. It allows you to adjust feeding in the key phases of plant development for correction, strengthening of missing factors in the development of plants and obtaining the required characteristics of marketable products (protein, gluten, brewing barley, etc.).
In addition to all the above advantages, UAN does not pollute the environment, improves nitrogen consumption during drought, the operating costs for its application are significantly lower than other fertilizers. UAN is non-toxic, non-flammable and explosive, (сompare with saltpeter in bags). The use of UAN is made with the greatest accuracy of the application rate. Can be transported in any containers (plastic, stainless, carbon steel).
The norms and doses of UAN application depend on the type of crop, the time and method of application, the predecessor and other factors. There are no special restrictions.
The first spring top feeding of winter crops is carried out after the snow falls during the renewal of vegetation of plants, during tillering with a dose of 30-40 kg. AS (active substance) per hectare, when the temperature does not exceed 10 ° C, UAN does not require dilution. It is possible to increase the rate of fertilization, depending on the physiological state of the plants.
The second foliar fertilizing is done in combination with the addition of plant protection products, growth regulators in the phase of the beginning of the outlet into the tube, while the single nitrogen norm should not exceed 30 kg. AS. In the second feeding of winter UAN, in order to avoid burns, it is advisable to dilute with water in a ratio of 1: 2, and when combined with a herbicide 1: 3 or 1: 4. If it is necessary to introduce additional nitrogen, a third late fertilizing is possible in the phase of the appearance of spikelets with a norm not exceeding 10 kg of the active substance.
When applying UAN in feeding on vegetating plants, the dose of nitrogen should not exceed 10-20 kg. A.S. with a mandatory dilution of water in a ratio of 1: 4 due to possible burns of plants.
Under UAN barley, it is most expedient to make it as the main fertilizer for pre-sowing cultivation.
When using UAN as a foliar top feeding, the pH of the solution should be in the range of 8-9. The effectiveness of this fertilizer depends largely on weather conditions. It is maximal when the solution remains on the leaf surface for a long time. Therefore, highly effective crop treatment is achieved in cloudy, cool weather.
Immediately after heavy rains, strong dew, it is not recommended to apply UAN in the mixture, since the sediments make the structure of the upper plate of the leaf more permeable (correspondingly more sensitive), so the spraying of the crops should be carried out after the leaves of the plants dry.
The optimal time of day for the application of UAN in a mixture with herbicides is an evening time, since the absorption of nitrogen at night is slower. When applying UAN, it is necessary to use sprayers with droplet size twice as large as herbicides.
Summarizing the advantages of applying UAN to granulated fertilizers, it is possible to note such advantages and disadvantages:
High application efficiency in all climatic zones, including arid zones.
More uniform application, precise dosage of distribution over the area.
The possibility of using at different stages of vegetation.
Rapid penetration into the soil without the need for binding (except alkaline soils) and therefore better adaptability to mini-till and no-till technologies.
Reduction of technological costs due to the possibility of mixing of the UAN with liquid mineral fertilizers and pesticides (primarily with microelements).
Low cost per unit of active substance in comparison with granular forms.
Lack of biuret.
The risk of plant burns, caused by the rate of application, the phase and peculiarity of vegetation culture, weather conditions.
Special conditions for transportation and storage are required.
The need for special equipment to transport and use UAN.