Everyone knows: for the body to exist, the presence of oxygen, hydrogen, carbon and nitrogen is necessary. It is clear that nitrogen is one of the main elements in the life of both plants, humans and animals. For plants, the source of nitrogen is, of course, soil. Depending on the type of soil, its “deterioration”, the amount of nitrogen in it also changes. Most often, various cultures feel nitrogen deficiency, growing on sandy and sandy loam soils. It is these types of soils that always need additional enrichment with nitrogen fertilizers, so that the plants on them feel normal.
- Soil nitrogen content
- Why do plants need nitrogen?
- Varieties of fertilizers containing nitrogen
- Crops for which nitrogen is especially important
- Rules for the use of nitrogen fertilizers
- The consequences of a lack of nitrogen
- Could there be harm from nitrogen fertilizers?
Soil nitrogen content
It has been established that a significant proportion of nitrogen in the earth is concentrated in its layer, called humus, in it more than 5% of nitrogen. Naturally, the thicker the humus layer, the greater the amount of nitrogen, therefore, on this soil plants feel better.
Humus is a very persistent substance, its decomposition is slow, therefore, the release of mineral substances from this layer also occurs rather slowly. Only one percent of the five that is in the soil is a mineral compound that is soluble in water, which means it is available for consumption by plants.
Consequently, even in the presence of a thick layer of humus, additional dressing of plants is necessary, although at lower doses.
Why do plants need nitrogen?
This element, it turns out, is not in every organic compound. For example, there is no nitrogen in sugars, fiber, oil, and starch. There is nitrogen in the amino acid and protein. Nitrogen is an important component of nucleic acid, which is the main component of literally any cell responsible for protein synthesis and duplication of hereditary data (duplication is the formation of additional hereditary material identical to that already in the genome).
Even chlorophyll, which is known to promote the absorption of solar energy by plants, also has nitrogen in its composition. In addition, nitrogen is present in various components of the organic medium, for example, in alkaloids, lipoids and similar substances.
All the aboveground mass of plants has nitrogen, and most of this element is contained in the very first leaf blades. With the completion of flowering and the beginning of the formation of the ovary, this substance flows to the reproductive organs of plants and accumulates there, forming proteins.
During the ripening period of the nitrogen is taken from the vegetative organs in the maximum quantity, and they are greatly depleted. If there is a lot of nitrogen in the soil and the plant will consume it in large quantities, then this element will be distributed over almost all organs of the plant, which will lead to rapid growth of the aboveground mass, delays in the ripening of berries and fruits and a decrease in the total crop of plants.
Only a balanced concentration of nitrogen in the soil can guarantee high yields and sufficient product quality.
Those plants that consume nitrogen in abundance, and not in excess, can fully develop, form standard leaf blades of a typical, often green, color, otherwise they will fade and form mediocre crops.
Varieties of fertilizers containing nitrogen
Nitrogen fertilizers are substances that contain nitrogen compounds. In total, there are several main groups of nitrogen fertilizers. These are nitrate fertilizers (calcium and sodium nitrate), ammonium fertilizers (ammonium chloride and ammonium sulfate), ammonium nitrate fertilizers (ammonium nitrate), amide fertilizers (urea) and liquid nitrogen fertilizers (ammonia water or anhydrous ammonia).
Nitrogen fertilizers, nitrate group
Start with calcium nitrate, - its chemical formula is Ca (NO₃) ₂. Externally, calcium nitrate is a white granules in which nitrogen is contained up to 18%. This fertilizer is suitable for soils with high acidity. With the systematic and annual introduction of calcium nitrate into the soil with high acidity, an improvement in its properties is observed. Calcium nitrate is highly soluble in water, so you need to store fertilizer in bags that do not allow water to pass through.
When making calcium nitrate, you need to remember that its mixing with phosphorus fertilizers is unacceptable.
The next fertilizer is sodium nitrateIts chemical formula is NaNO₃. This fertilizer is crystalline, it contains a little less - up to 17% nitrogen. Sodium nitrate is highly soluble in water and perfectly absorbed by the roots of plants. This fertilizer is versatile and suitable for various crops. This fertilizer can not be applied in the autumn period: the nitrogen contained in it will be actively washed off into groundwater.
Given the excellent solubility in water and hygroscopicity, this fertilizer must be stored in dry places.
The next group is ammonium fertilizers. In the first place in this group is ammonium sulfate, its chemical formula has the form (NH4)2SO4. Externally, this fertilizer is a snow-white powder, which contains a little more than 20% nitrogen.
Ammonium sulfate can be used both as the main nitrogen fertilizer and as an additional top dressing. The application of this fertilizer can be carried out in the autumn period: nitrogen from it is fixed in the soil without being washed off into groundwater.
With the annual and systematic introduction of ammonium sulfate into the soil, soil acidification can occur, for which this fertilizer must be mixed with lime or chalk in a ratio of one to two.
Ammonium sulfate is not hygroscopic, therefore, storage of its problems usually does not arise. The main thing to remember is that you can not apply this fertilizer in combination with any alkaline top dressing, because there is a risk of suppressing nitrogen activity.
Ammonium chloride, - its chemical formula is NH₄Cl. This fertilizer contains about 26% nitrogen. Externally, ammonium chloride is a yellow-white powder. When making ammonium chloride, it is not washed away from the soil, during storage this fertilizer does not cake and does not require grinding even after many years of storage. Nitrogen released from ammonium chloride into the soil is perfectly absorbed by plants.
The main disadvantage of this fertilizer is the chlorine contained in its composition. So, when 10 kg of nitrogen are applied to the soil, in terms of the active substance, approximately twice as much chlorine gets into the soil, and it is considered poisonous for most plants. Given this, the introduction of ammonium chloride should be carried out exclusively in the autumn in order to deactivate the chlorine component, however, up to 2% of nitrogen is lost along with this.
Ammonium nitrate fertilizers
The next category is ammonium nitrate fertilizers, the leader in this group is ammonium nitrate. Chemical formula ammonium nitrate looks like this - NH₄NO₃. This fertilizer has the appearance of an off-white granular powder. Fertilizer contains about 36% nitrogen. Ammonium nitrate can be used as a main fertilizer or as an additional top dressing.
This fertilizer is categorized as a ballastless substance, therefore its main application falls on regions with a deficiency of water moisture. It is noteworthy that on soils with excess moisture, the effectiveness of the use of this fertilizer is practically minimized, since the nitrogen contained in the fertilizer is almost completely washed off into groundwater.
Due to the increased hygroscopicity, ammonium nitrate does not tolerate storage in damp rooms, where it hardens and cakes quite quickly. Of course, this does not mean that the fertilizer becomes worthless, just before putting it into the soil, it will be necessary to grind the saltpeter, which is sometimes quite difficult.
In the event that your plans include the creation of a mixture of ammonium nitrate and phosphorus fertilizer, for example, superphosphate, then you should first mix superphosphate with any neutralizing fertilizer, for example, dolomite flour, chalk or lime, and the next step is to mix it with ammonium nitrate.
Do not forget that the systematic and annual introduction of ammonium nitrate into the soil leads to an increase in its acidity level. It is noteworthy that the level of soil acidity increases most actively over time, and at the initial stages of its application, the change in acidity is imperceptible.
In order to prevent soil acidification, ammonium nitrate must be added together with chalk, dolomite flour and lime in a ratio of 1 to 2.
It is interesting that at present, ammonium nitrate in its pure form is practically not sold, it is sold in the form of various mixtures. It is very popular and has good reviews when using a mixture consisting of 60% ammonium nitrate and 40% of various neutralizing components. In this ratio, approximately 19-21% of nitrogen is in the mixture.
Group - Amide Fertilizers
Urea, - its chemical formula has the form CH4N2O. Urea is called otherwise - urea, this fertilizer is considered one of the most effective. Urea contains about 47% nitrogen, sometimes 1% less. Outwardly, these are snow-white granules. This fertilizer is characterized by an increased ability to acidify the soil, therefore, it can be applied only with neutralizing substances - dolomite flour, chalk, lime. Urea is rarely used as the main fertilizer, it is usually used as an additional foliar top dressing. This excellent foliar fertilizer is also because it does not burn leaf blades, but is well absorbed by plants.
In total, two brands of urea are known, which are called A and B. The brand under the name A does not belong to the category of highly effective and is rarely used in crop production. Typically, brand A urea is used for a feed additive for animals, for example, goats, cows, horses. The urea brand with the name B is urea processed with additives, used specifically as fertilizer.
Liquid nitrogen fertilizers
Ammonia hydrate, or ammonium hydroxide (ammonia water or liquid ammonia). Chemical formula of ammonium hydroxide NH4OH. In fact, ammonia water is ammonia dissolved in water. In total, there are two types of liquid ammonia, the first contains nitrogen at least 19% and no more than 26%, and the second may contain from 15% nitrogen to 21%. Usually, ammonia water is introduced using special equipment capable of plugging this fertilizer into the soil to a depth of about 14-16 cm.
The advantages of liquid fertilizers are their extremely low price, fast assimilation by plants, a long period of action and an even distribution of fertilizers in the soil. There are also disadvantages - this is a rather complicated transportation and storage, the possibility of severe burns on the leaves when fertilizer gets on their surface and the need for special equipment designed for applying liquid fertilizers.
Organic Nitrogen Fertilizers
As you know, nitrogen is present in organic compounds, but its amount there is small. So, for example, in cattle litter, nitrogen is not more than 2.6%. In bird droppings, which are quite toxic, its up to 2.7%. Nitrogen is also present in compost, but its amount there, depending on the “ingredients” of compost, is very different. Most nitrogen in compost prepared from lake silt, leaf litter, green mass of weeds and lowland peat. Given the instability of the nitrogen content in organic fertilizers, its use as the main fertilizer is not desirable and threatens with nutritional deficiency and nitrogen starvation for plants. In addition, such fertilizers, although slowly but still acidify the soil.
Crops for which nitrogen is especially important
In general, each crop needs nitrogen, but the application dose varies for certain crops. Given this, all plants can be grouped into categories of the need for nitrogen.
In the first category you can include plants that need to be fed with nitrogen before planting them in the ground to activate growth and development. For such crops, approximately 26-28 g of nitrogen, in terms of ammonium nitrate and per square meter of area, are needed per square meter. This category includes, from vegetable crops: potatoes, cabbage, bell pepper, eggplant, zucchini, pumpkin and rhubarb; from berry and fruit: plum, cherry, raspberry, blackberry and strawberry; from flower: lilac, rose, dahlia, peony, violet, phlox, balsam, cloves, nasturtium and zinnia.
Second group - These are crops that need less nitrogen. Usually, only 18-19 g of nitrogen are enough, in terms of ammonium nitrate and per square meter of area. Vegetable crops include: tomatoes, parsley, cucumber, carrots, corn, beets and garlic; from fruit and berry: apple tree, currant, gooseberry; from flower: all annuals and delphiniums.
Third category - These are plants that need nitrogen in moderation, not more than 10-12 g per square meter, calculated on ammonium nitrate. From vegetables to this category, you can include: early ripening potatoes, salad crops, radishes and onions; from fruit - it is a pear; from flower: bulb, primrose, adonis, saxifrage and daisy.
Final category requires a minimum amount of nitrogen per square meter, not more than 5-6 g in terms of ammonium nitrate. Vegetable crops include spicy herbs and legumes; from flower - poppy, azalea, juvenile, heathers, stonecrop, Erica, purslane, rhododendrons and cosmeas.
Rules for the use of nitrogen fertilizers
Remember that only optimal doses of nitrogen fertilizers can positively affect the development and growth of various crops, and fertilizing should be calculated based on the percentage of nitrogen in a particular fertilizer, and also make them according to the type of soil, season and type of plant.
So, for example, when nitrogen is introduced into the soil in autumn, there is a risk of its washing off into groundwater. Therefore, the most suitable period for applying fertilizers containing nitrogen is precisely spring.
If you plan to fertilize soils with high acidity, be sure to mix nitrogen with various components that neutralize the acidifying effect - chalk, lime, dolomite flour. Thus, fertilizers will be absorbed better, and the soil will not be acidified.
It is very important for residents of the steppe zone and forest-steppe, where the soils are mostly dry, to apply nitrogen fertilizers periodically, without sharp interruptions, which can affect plants in the form of delays in growth, development, and yield reduction.
It is better to carry out nitrogen fertilizers in the chernozem soil 11-12 days after the snow melts. The first top dressing is preferably carried out using urea, and when plants enter the active phase of the growing season, add ammonium nitrate.
The consequences of a lack of nitrogen
We have already partially mentioned this, but nitrogen deficiency is not only inhibited growth. In addition, quite often the leaf blades of plants begin to acquire an atypical color, they turn yellow, and this is the first signal to fertilizer application. With a severe nitrogen deficiency, in addition to yellowing of the leaf blades, their tips slowly begin to dry out.
Could there be harm from nitrogen fertilizers?
Yes, maybe in case of their oversupply.Usually, with an excess of nitrogen, the aerial mass of plants begins to develop too actively, shoots thicken, leaf blades increase, internodes become larger. The green mass acquires atypical splendor and softness, and flowering is either weak and short, or does not occur at all, therefore, the ovary does not form and fruits and berries do not form.
If there is a lot of nitrogen, then something like burns appears on the leaf blades, in the future such leaflets die off and fall off ahead of time. The death of foliage sometimes leads to a partial death of the root system, which is why the application of nitrogen must be strictly normalized.
The results. So, we realized that all plants need nitrogen fertilizers, however, their dosages need to be correctly determined and applied in accordance with the recommended terms, based, inter alia, on the properties of the fertilizers themselves.