About urea in detail. Features of application for various cultures
Urea, or urea, belongs to the category of nitrogen fertilizers. Urea is also used as fertilizer by large farms and gardeners, as well as gardeners who own several hundred square meters of land. This demand for urea is explained very simply, it is quite effective and is cheap.
Urea is a substance whose chemical formula has the form (NH2)2CO. Urea dissolves well in sulfur dioxide, liquid ammonia and in water. Urea is obtained by synthesis from ammonia and carbon dioxide at a temperature of about 150 degrees above zero. In addition to being used as a fertilizer, urea is also used in the food industry - usually as a food additive under the number E-927, most often this additive is used in various chewing gums.
Urea contains almost half of nitrogen (about 44%). Plants need nitrogen in the first place for their full growth and development. In the case of urea, it is important to know that plants will be able to use only half the dose of nitrogen contained in this fertilizer. However, despite this, it is better not to increase the dosage of urea due to the nitration process.
If the soil is poor in nitrogen, then it is better to increase its content by combining urea and magnesium sulfate, then nitration in such a volume as when applying large doses of urea is not observed.
Urea is usually produced under two brands - A and B. Usually, grade A urea is used in industry, but B is used as fertilizer. Externally, these are granules of whitish color with a noticeable shade of yellowness. In the past few years, urea-containing tablets have also begun to be produced, but it is still difficult to find them on the free market. Tablets are good in that they have a special shell that prevents the evaporation of nitrogen before fertilizer enters the soil during surface application. Given this, tablets in weight ratio need significantly less than pellets, however, the cost of urea in tablets is higher, so the economic effect is almost imperceptible.
The advantages and disadvantages of urea
The undoubted advantages of urea are the acceleration of the growth of the vegetative mass, the increase in the protein content of cereal crops, the strengthening of plant immunity, the prophylaxis against the propagation of pests, the undoubted ease of use, including due to complete dissolution without residue.
Urea disadvantages: an overdose of fertilizer in most cases causes severe burns to plants and can lead to their death, urea does not combine with a number of fertilizers (wood ash, calcium nitrate, simple superphosphate, lime, chalk, gypsum and dolomite flour).
Urea can be combined with phosphate rock and ammonium sulfate - for quick application (these compounds are not suitable for storage) or with sodium nitrate, potassium nitrate, ammonium nitrate, potassium chloride, potassium sulfate and manure - these compounds can be stored for a long time.
Why can not combine urea with a number of fertilizers? The fact is that this fertilizer is highly acidic, so if you add lime, wood ash, chalk or dolomite flour at the same time as urea, a reaction will occur that simply neutralizes this composition, simultaneously releasing a lot of salts in the soil.
If you mix urea and monophosphate or calcium nitrate, then the soil will not be salted, but acidified, because all these fertilizers are based on acids.
How to use urea as a fertilizer?
The vast majority of nitrogen, and, consequently, nitrogen fertilizers are necessary for plants in the spring, at a time when active sap flow and vegetation begin. The introduction of urea in the autumn can cause activation of growth processes and plants simply freeze or freeze severely in winter. However, if the site is empty and planting on it is planned in the autumn, then in the autumn you can fertilize the soil with urea, only you need to keep in mind that about 40-45% of the nitrogen contained in urea can be decomposed quite quickly in the autumn when it is introduced into the soil and literally disappear.
When applying urea in spring, it is better to use not dry fertilizer, but dissolved in water, this will minimize the risk of burns in plants. It should be remembered that even urea dissolved in water is best applied to pre-moistened soil or after heavy rain. It is better to introduce dry urea to the areas intended for planting, and to do this not by simply scattering it on the surface, but with obligatory incorporation into the soil by digging or plowing. In this case, a minimum amount of time should pass from spreading urea over the soil surface to digging or plowing the soil, otherwise most of the nitrogen can simply evaporate or turn into ammonia. General terms for the decomposition of urea are quite short - usually no more than five days.
A serious miscalculation is allowed by gardeners who scatter urea granules in the spring in the garden directly into the snow that has not melted yet or add urea in the rain (also by spreading it over the surface of the soil). With this application, most of the nitrogen contained in the urea will either evaporate or be washed into deeper soil layers inaccessible to the roots.
The most optimal variant of urea top dressing of fruit plants and berry bushes is to make it dissolved in water in a fossa or trench dug in the near-trunk zone or near-trunk strip in a depth of 3-4 cm (under powerful plants up to 10 cm). Immediately after fertilizing, both the pit and the trench should be buried. This application prevents the evaporation of nitrogen contained in the urea, and does not allow its leaching into deeper layers of the soil.
During the growing season, the use of urea as a top dressing is most justified if the plants show obvious signs of nitrogen starvation, that is, the plants develop extremely slowly, have a depressed appearance, their leaf blades are atypically small in size, and the ovaries are shed to a large extent. The initial sign of a lack of nitrogen is yellowing or lightening of the leaf blades, however, in this case, a mistake can also be made, since the plants react in the same way to lack of moisture and lack of iron in the soil.
To distinguish between a lack of iron and moisture from a lack of nitrogen, you need to take a closer look at the leaf blades of plants in the daytime: if there is really little nitrogen, then in the daytime you will not notice wilting of leaf blades, and if there is little moisture or iron in the soil, leaf withering will be observed. In addition, with the lack of iron, the young leaves will turn yellow first and only after that the yellowing will be noticeable on the old leaf blades, but if there is a lack of nitrogen in the soil, the old leaf blades will turn yellow first, and only then the young ones.
In the midst of the growing season, with a lack of nitrogen in the soil, urea can be applied both in dry form and in liquid form, or it is possible to treat plants with it by performing foliar top dressing.
How to make liquid fertilizer from urea?
Urea liquid fertilizer is quite simple to prepare in view of its good solubility in water (even without sediment). Most often, solutions containing either 0.5% urea or 1% are made. This means that in a bucket of water you need to dissolve either 50 and 100 g of urea, respectively, or 5 and 10 g of urea to dissolve in a liter of water.
Urea application rates
Urea is considered a universal nitrogen fertilizer, it is suitable both for vegetable crops, and for berry, fruit and flower, and can be used on any type of soil.
If you follow the instructions for applying urea, then the dosages will be as follows: in the form of granules, that is, in dry form, about 5-10 g of fertilizer should be applied per square meter of soil, deepening it by 3-7 cm (up to 10 cm, depending on plant size) into pre-moistened soil; fertilizer dissolved in water should be applied in an amount of 20 g per square meter of soil for both vegetable and fruit or berry crops; treatment of urea dissolved in water, that is, foliar feeding - here the dosage for vegetables is as follows - 5 g per bucket of water in terms of square meter, for bushes and trees - 10 g per bucket of water and also per square meter; when planting plants in the soil, 4-5 g of fertilizer should be introduced into the planting hole, but be sure to mix it with the soil to prevent contact of the roots with urea.
The use of urea for various crops
Both winter and spring garlic can be fed with carbamide in early June. Further, you can not use urea for garlic, this can lead to an increase in green mass to the detriment of the bulbs. You need to add urea under garlic in a form dissolved in water and add potassium chloride to the solution - 10 g of urea, 10 g of potassium chloride in a bucket of water, this is the norm per square meter of garlic beds.
It is appropriate to feed cucumbers with urea only two weeks after transplanting seedlings to the site. Urea is introduced in the form dissolved in water at a rate of 15 g per bucket of water in terms of square meter of area. It is permissible to add 45-50 g of superphosphate to the solution. Top dressing will be most effective if the soil is well moistened before application.
In a greenhouse, cucumbers can be treated with urea, that is, foliar top dressing, in particular, it is needed when changing the color of leaf blades (discoloration).
For complete foliar feeding of cucumbers in a greenhouse, it is necessary to dissolve 15 g of urea, 20 g of superphosphate and 15 g of potassium chloride in a bucket of water. It is desirable to process plants in cloudy weather and always after preliminary watering.
Tomatoes like urea treatment. Tomatoes are usually fertilized with urea when planting seedlings on a plot, adding 12-14 g of a mixture of urea and superphosphate to each well (6-7 g of each fertilizer).
Usually, urea on cabbage is used during the first feeding. Before top dressing, cabbage is abundantly watered, then 30 g of urea is dissolved in a bucket of water and this solution is consumed per square meter of soil.
Under potatoes, characterized by poor assimilation of mineral fertilizers, the soil must be fertilized with urea before the tubers are planted. Usually fertilize the soil a couple of weeks before planting potatoes, while it is advisable to add urea along with potassium fertilizer. One hundred square meters needs about 1.5 kg of urea and 0.5 kg of potash fertilizer.
In the event that, for some reason, you did not add urea before planting potatoes, then it can be added to the soil five days after planting tubers, but not in a dry form, but dissolved in water. The norm is about 15-16 g per bucket of water, this solution is enough for 20 plants (about 0.5 liters each).
Wild strawberry (strawberry)
It is advisable to add urea to this culture only if necessary, because if garden strawberries feel a nitrogen deficiency, then the size of the berries will be small, as well as their quantity, and the taste will be mediocre. And in case of excess nitrogen, the berry will be watery and devoid of aroma. It is recommended to apply urea under garden strawberries immediately after the snow melts, 15-20 g of fertilizer dissolved per square meter, not more than. If you need higher doses of nitrogen fertilizers, it is better to use nitrophoska or diammophos.
Fruit trees and large shrubs
Urea top dressing fruit trees and large shrubs respond quite well. Urea can feed such plants up to three times per season. Usually they are fed immediately after the snow melts, during flowering and during the ripening period. Before applying urea, the soil in the near-trunk or near-trunk strip is loosened, watered, and then urea is applied so that the fertilizer is buried 3-4 cm deep into the loosened soil. After applying urea, it is advisable to cover the soil.
Feeding rates vary depending on the age of the plants: for example, before the fruiting of trees and large shrubs, they are almost a third less. For example, for an apple tree that has not yet begun to bear fruit, you need about 75-80 g of fertilizer, for cherry 85-90 g, for plum 110-115 g and for shrubs (irrigation, chokeberry, etc.) 100-110 g. After entry for fruiting, the apple tree already requires 150-160 g per tree, cherry 110-120 g, plum 125-140 g and shrubs (shrimp, chokeberry and the like) 135-145 g per bush.
Urea flowers must be fertilized at the very beginning of their active growth in order to increase the vegetative mass. Further, such top dressing will become inappropriate, because, to the detriment of flowering, the vegetative mass will continue to form, as the flower growers say, "the flower will go into the foliage." It is noteworthy that with an excess of nitrogen, the flowers may not form buds at all, and if there is a lot of nitrogen, then there will be a massive fall of the buds and inflorescences that have fallen, both with blossoming flowers and with undisclosed ones.
Urea should be applied under flower crops only in a form dissolved in water, for which you need to dissolve about four grams of this fertilizer in a liter of water and use this rate for a large flower such as a peony or divide it into two parts if the flower is small, such as a tulip or lily of the valley.
Urea Use Against Pests
Urea is usually used against pests if there is no possibility or desire to use chemistry. Plants are treated with it, abundantly watered, usually until buds open, when the air temperature rises above five degrees Celsius. Using treatments with urea, you can get rid of weevil, aphids, apple flower beetle and tinnitus. For this, it is appropriate to use fertilizer dissolved in water in an amount of 30 g per bucket of water. If last season there was a strong pest damage, then the dose can be increased to 100 g per bucket of water, but this dosage cannot be exceeded, this can harm the plants.
Urea storage rules
Urea should be stored, given its increased hygroscopicity, in a dry and ventilated room, with an air humidity of 50% or lower. Urea can be stored in wetter rooms, but in a hermetically sealed container.
Usually the guaranteed shelf life is only six months, but the period of use of urea is unlimited. The fact is that the manufacturer guarantees the absence of caking of urea for six months, and then before use, in case of caking, it will need to be crushed and can be used for an unlimited amount of time. However, it is necessary to take into account the fact that over the years the amount of nitrogen in urea can be insignificant, but fertilizers with very long storage periods must be reduced and this fact should be taken into account.
That's all we wanted to tell about urea, the information seems to be quite sufficient, but if you still have questions, we will be happy to answer them in the comments.