Description of the UAN

Mineral fertilizers are represented in three main groups: granular, liquid and water-soluble. The most widespread is the granular form due to the availability of the form of its introduction.

Liquid mineral fertilizers on the market are represented in the following assortment: anhydrous ammonia (which can be attributed to gaseous form sooner), ammonia water, liquid-complex fertilizers and UAN (carbamide-ammonium mixture).

UAN contains all three forms of nitrogen.
Amide form of nitrogen (NH2 +). It is easy enough to penetrate the plant through the leaf device, but it will take considerably longer to penetrate the plant through the root. For this, the amide form will have to be transformed first into ammonium form, and only then – in the nitrate form, and even then under the condition of positive temperatures.
The ambient temperature directly affects the rate of passage of the transformations of the nitrogen forms, since this process is carried out with the participation of soil microorganisms. As can be seen from Table 1, the higher the temperature, – the faster the process of transformation.
The nitrate form is quickly and completely absorbed by the root system of plants, whereas the ammonium form (NH4 +) is not absorbed by either leaves or roots. It, like the amide form, requires the participation of microorganisms and positive temperatures.

 

NH2 ⇨ NH4	NH4 ⇨ NO3
2ºC - 4 days 10ºC - 2 days 20ºC - 1 days	5ºC - 6 weeks 8ºC - 4 weeks 10ºC - 2 weeks 20ºC - 1 weeks

Table 1.
Thus, when applying UAN, which has various forms of nitrogen, we get a prolonged effect of its assimilation by plants.

Unfortunately, when ammonium nitrate is applied in conditions of temporary or permanent excess of moisture (for example, in the spring), a significant part of nitrate nitrogen is washed out with soil moisture, when it leaves below the root zone. Nitrogen at the same time becomes inaccessible to plant nutrition.

In order to ensure the optimal nutrition of plants with nitrogen, it is necessary first of all to carry out fractional fertilizing of agricultural crops, since nitrogen consumption occurs during the whole vegetation period. In connection with the above, entering the UAN in the spring – optimal solution.

UAN 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). The density of liquid fertilizer is up to 1.34 kg/m3.

The only nitrogen fertilizer that contains three forms of nitrogen:

• Nitrate nitrogen – provides instant action,
• Ammonium nitrogen – in the process of nitrification passes into the nitrate form,
• Amide nitrogen – as a result of the activity of soil microorganisms passes into the ammonium form, and then into the nitrate form.

Thus, UAN provides prolonged nutrition of plants with nitrogen. In view of the lack 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 under high-temperature conditions and without precipitation after application.

Nitrogen losses when applying UAN do not exceed 10% of total nitrogen, while when applying granular nitrogen fertilizers they reach 30-40%.

One of the most important advantages of UAN is its high adaptability:

• The introduction of UAN as liquid fertilizer is much more uniform than solid, granular.
• UAN can be combined using pesticides in one tank mix
• It is advisable 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 development 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 fertilizing is caused by the following factors: stressful situations (low temperatures, freezing, 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 easily accessible elements from the soil are exhausted, or their assimilation «does not keep pace with the rate of growth of the plant». 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. The amide form of nitrogen quickly penetrates through the leaf surface of cereal grains and other crops.

The leaf feeding can be combined with the application of trace elements and/or plant protection products, but it is necessary to dilute the UAN with water in a ratio of 1: 1 or 1: 2 (depending on the temperature regime).

UAN – it is, first of all, a very flexible additional tool for feeding crops in a highly productive environment. In addition to all the above benefits, UAN does not pollute the environment, improves nitrogen consumption during drought, the operating costs for its application are significantly lower than other fertilizers.

1. In the fall – for basic processing.
2. In the spring – under the presowing treatment.
3. During the growing season of crops for root and foliar feeding.

The norms and doses of UAN application depend on the type of culture, the time and method of introduction, the predecessor and other factors. When applying UAN, it is necessary to use sprayers for large-droplet application of liquid fertilizers.

The best time for foliar top feeding with UAN solutions is morning (in the absence of dew) and evening hours. In the cool and cloudy weather, this work can be done during the day. You should not feed plants with UAN solutions at temperatures above 20^oC, low relative air humidity (less than 56%), on a sunny day, as in these cases, burns of the leaf surface of plants may happen. Especially prone to burns are young plant leaves. The most effective treatment is UAN in cloudy weather.

ADVANTAGES

LIMITATIONS

High application efficiency in all climatic zones, including arid zones. More uniform application, accurate dosage of the area distribution. The ability to use 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. Prolonged action. Reduction of technological costs due to the possibility of introducing UAN in liquid fats, as well as in a mixture with pesticides and other liquid mineral fertilizers (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, phase and peculiarity of vegetation culture, weather conditions. Special conditions of transportation, storage are necessary. The need for special equipment for using liquid fertilizers.

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. Immediately after heavy rains, strong dew, it is impossible to apply UAN, since the sediments make the structure of the upper plate of the leaf more permeable (respectively more sensitive), so the treatment of crops should be carried out after the leaves of the plants dry.

The optimal time of day for introducing UAN in a mixture with herbicides is an evening time, as the absorption of nitrogen at night is slower.

Summing up the advantages of applying UAN to granulated fertilizers, you can note such advantages and disadvantages:

When feeding the UAN, it is necessary to achieve such a drop size that the substance rolls off the plant, only by moistening the sheet. Otherwise, it may get burnt. And the deflector nozzles just give the needed large-droplet solution. Slot nozzles can be used only when applied with herbicides, with mandatory dilution of UAN with water;
Do not forget that to work in windy weather, use extension hoses.

• For the application of granular fertilizers, moisture is needed so that the granule can dissolve and be absorbed by the plants. But in the conditions of our agroclimatic zone such a period, when moisture is available and is in the required quantity - is very short-lived. Therefore, the transition to the use of the UAN expands the period of fertilizer application, thereby reducing the burden on the technical system and guaranteeing the fertilization of the crop, reducing the risk of "not falling within the technological timeframe".
• When using granular fertilizers, we were limited in time because of the need to introduce them along the permafrost so that the technician could enter the field and not make a rut. Now this problem has been removed, UAN is introduced not only by frozen ground, but also in a later period, UAN flowing through plants, quickly absorbed into the soil and feeds plants.
• The application of UAN over the field is more evenly and much better than the application of granular fertilizers by spreader-driers
• To implement the UAN, much less auxiliary equipment is required than when applying granular. Logistics is simpler and more efficient: less time is spent on loading, transporting fertilizers. And the spring day, as is known, feeds the year.
• In addition, when using this fertilizer, the productivity of aggregates is much higher.
• UAN works both through the leaves and through the roots, due to the fact that it has three forms of nitrogen, the amide form is absorbed through the leaf surface, and the nitrate and ammonium form is used – through the root system.

Spraying plants with UAN fertilizer can cause the appearance of necrotic spots on the leaves or tissue damage. The degree of damage to the leaves depends on the culture, the phase of its development, the fertilizer dose and, especially, the weather.

The more the stage of plant development – the lower the concentration of UAN can they withstand. The maximum dose of UAN, which we made on winter wheat – 400 kg/ha in the tillering phase in November, when the air temperature was + 5°C. Burns were not!

The minimum air temperature is -8°C (if the temperature is below, the crystallization begins, the system hoses, the spray hoses).
Very important for winter wheat is the first spring application of UAN. Due to the fact that in the spring there is practically no nitrogen in the soil, and the plants are awakening from the winter and require nutrients, the first watering with UAN is the best way to provide the culture with nitrogen. The dose of UAN in this period (tillering - the beginning of spring regrowth) is 100 kg / ha.

Second watering – tillering before going into the tube – 150 l/ha for the planned grain yield of 5-6 t/ha.

On winter rape – the dose of UAN is higher. We make the UAN by the method of irrigation on winter rape with a dose of 200/250 kg/ha on frozen thawed soil.

On spring crops – 100 kg/ha in the phase 3 of the sheet - the beginning of tillering.

Making a UAN is not recommended when the air temperature exceeds + 20°C and air humidity is more than 56%, since it is possible to burn the plants. It is permissible to apply UAN at a temperature higher than + 20°C, but with low doses of the solution (60-80 l/ha) and under condition of dilution with water 1: 1.

For example, using a UAN mixture of 200 kg/ha and a solution of ammonium sulfate 100 kg/ha on winter wheat in phase 35 (the middle of the tubing) with large-droplet irrigation, – burns of the tips of leaves were obtained, the culture suspended its development for several days.

You cannot use liquid fertilizer UAN, growth regulators and fungicides in rainy weather.

Timing of fertilizer application on winter crops often coincides with the time of crop treatment with herbicides, fungicides and insecticides. Therefore, the introduction of liquid nitrogen fertilizer UAN can easily be combined with plant protection products from weeds and diseases, but subject to compulsory dilution with water.

The safety data sheet developed in accordance with the requirements of Regulation (EC) 1907/2006 (REACH), for the urea-ammonium nitrate (UAN).
ТУ У 24.1-00203826.024-2002 TU U 24.1-00203826.024-2002	КАС-28/UAN-28	КАС-30/UAN-30	КАС-32/UAN-32
Mass fraction of nitrogen, %	28,0 ±1	30,0 ±1	32,0 ±1
Mass fraction of ammonium nitrate Mass fraction of carbamide	37,0 - 42,0 29,0 - 33,0	40,0 - 45,0 31,0 - 35,0	43,0 - 48,0 33,0 - 37,0
Alkalinity, %	0,05 - 0,50	0,05 - 0,50	0,05 - 0,50
Density at temperature 200C, gr/sm3	1,265 - 1,285	1,285 - 1,306	1,306 - 1,326
Mass fraction of inhibitor "Novokor", %	0,010 - 0,015	0,010 - 0,015	0,010 - 0,015