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Nitrogen Fertilizers

, Admin

We all know: for an organism to exist, oxygen, hydrogen, carbon and nitrogen are 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, the soil. Depending on the type of soil, its "wear and tear", the amount of nitrogen in it varies. Most often, different crops feel nitrogen deficiency when growing on sandy and sandy loam soils. Exactly these types of soils always need additional enrichment with nitrogen fertilizers, so that plants feel well on them.

Nitrogen fertilizers
Mineral nitrogen fertilizer. © agrihol

Nitrogen content in the soil

It is established that the weighty proportion of nitrogen in the earth is concentrated in its layer called humus, it contains more than 5% nitrogen. Naturally, the thicker is the humus layer the more the amount of nitrogen, therefore plants feel more comfortable in such soils.

Thumus is a very stable substance, the process of its decomposition is slow, therefore the separation of minerals from this layer is also very slow. Only one per cent of five of the humus layer is a water soluble mineral compound, so it can be used by plants.

Hence even in the presence of a thick humus layer additional feeding is necessary for plants, though in lower doses.

What do plants need nitrogen for?

It turns out that not every organic compound has this element. For example, there is no nitrogen in sugars, fiber, oil and starch. There is nitrogen in amino acids and proteins. Nitrogen is an important component of nucleic acid, which is the most important component of literally every cell responsible for protein synthesis and duplication of hereditary data (duplication is the formation of additional hereditary material identical to that already present in the genome).

Even chlorophyll, which is known to help plants absorb solar energy, also has nitrogen in its composition. In addition, nitrogen is present in various components of the organic environment, such as alkaloids, lipoids and similar substances.

The entire above-ground mass of plants has nitrogen, with the most of this element contained in the very first leaf laminae. At the end of flowering and the beginning of ovary formation this substance flows to reproductive organs of plants and accumulates there, forming proteins.

In the period of seed ripening nitrogen is taken from vegetative organs in maximum quantity, and they are strongly depleted. If there is a lot of nitrogen in the soil and the plant will consume it in large quantities, this element will be distributed to almost all plant organs, leading to rapid growth of the above-ground mass, delays in the ripening of berries and fruits and reduces the total yield of plants.

Only a balanced nitrogen concentration in the soil can guarantee high yields and sufficient product quality.

Those plants that consume plenty of nitrogen rather than in excess can develop fully, produce standard leaf plates of typical, often green, color, otherwise they will wilt and form mediocre yields.

Nitrogen fertilizers
Corn treated with nitrogen fertilizer (background) and untreated. © Nora Nolden

Types of fertilizers containing nitrogen

Nitrogen fertilizers are substances that contain nitrogen compounds. There are several main groups of nitrogen fertilizers in total. 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

Let's start with calcium nitrate - its chemical formula is Ca(NO₃)₂. Externally, calcium nitrate is a snow-white granules, which contain up to 18% nitrogen. This fertilizer is suitable for soils with high acidity. With a planned and annual application of calcium nitrate in the soil with high acidity, there is an improvement of its properties. Calcium nitrate is perfectly soluble in water, so store the fertilizer in bags that are impermeable to water.

When applying calcium nitrate, remember that it should not be mixed with phosphate fertilizers.

The next fertilizer is sodium nitrate, its chemical formula is NaNO₃. This fertilizer is crystalline and contains slightly less - up to 17% nitrogen. Sodium nitrate is highly soluble in water and is very well absorbed by plant roots. This fertilizer is versatile and suitable for a variety of crops. This fertilizer must not be applied in autumn: the nitrogen it contains will be actively washed away into the ground water.

Bearing in mind the excellent solubility in water and hygroscopicity, this fertilizer must be stored in dry places.

Ammonium fertilizers

The next group is the ammonium fertilizer. At the first place in this group is ammonium sulfate, its chemical formula is (NH4)2SO4 . This fertilizer is a snow-white powder, which contains a little more than 20% of nitrogen.

Ammonium sulphate can be used as the main nitrogen fertilizer, and as an additional fertilizer. Applying this fertilizer can be carried out in the fall: the nitrogen from it is fixed in the soil without being washed away into the groundwater.

When making annual and systematic application of ammonium sulfate to the soil can be an acidification of the soil, for which this fertilizer must be mixed with lime or chalk in a ratio of one to two.

Ammonium sulfate is not hygroscopic, so storage is not usually a problem. The main thing to remember is not to apply this fertilizer in combination with any alkaline fertilizers, because there is a risk of suppressing the activity of nitrogen.

Ammonium chloride - its chemical formula is NH₄Cl. This fertilizer contains about 26% nitrogen. Ammonium chloride looks like a yellow-white powder. Ammonium chloride does not wash out from the soil, it does not cake when stored, and even after years of storage this fertilizer does not require grinding. Nitrogen released from ammonium chloride in the soil, perfectly absorbed by plants.

The main drawback of this fertilizer - is the chlorine contained in its composition. Thus, when you apply 10 kg of nitrogen in terms of the active ingredient, about twice as much chlorine enters the soil, and it is considered poisonous to most plants. Taking this into account, application of ammonium chloride must be done only in autumn, in order to deactivate the chlorine component, but up to 2% of nitrogen is lost with it.

Ammmonium nitrate fertilizers

The next category is ammonium nitrate fertilizers, the leader in this group is ammonium nitrate. The chemical formula for ammonium nitrate is as follows - NH₄NO₃. This fertilizer has the appearance of a whitish granular powder. The fertilizer contains about 36% nitrogen. Ammonium nitrate can be used as a basic fertilizer or as an additional fertilizer.

Categorizes this fertilizer as a ballastless substance, so its main use falls on regions with a deficit of water moisture. It is noteworthy that in soils with excess moisture efficiency of this fertilizer is reduced to a minimum, because the nitrogen contained in fertilizer, almost completely washed away into the groundwater. Of course, this does not mean that the fertilizer is useless, but before you apply it to the soil, it will be necessary to crush nitrate, which is sometimes difficult.

If you plan to create a mixture of ammonium nitrate and phosphate fertilizer, such as superphosphate, then initially you should mix superphosphate with any neutralizing fertilizer, such as dolomite flour, chalk or lime and the next step is to mix it with ammonium nitrate. It is noteworthy that the level of soil acidity increases most actively with time, while in the initial stages of its application the change in acidity is imperceptible.

In order to prevent soil acidification, ammonium nitrate should be applied together with chalk, dolomite flour and lime in a ratio of 1 to 2.

It is interesting that nowadays ammonium nitrate in pure form is practically not sold, it is sold as various mixtures. A mixture consisting of 60% ammonium nitrate and 40% of various neutralizing components is very popular and has good reviews. In this ratio, the mixture contains about 19-21% nitrogen.

Nitrogen fertilizers
Granules of nitrogen fertilizer - urea. © thechemco

Group - amide fertilizers

Urea - its chemical formula is CH4N2O. Urea is also called urea, and is considered one of the most effective fertilizers. Urea contains about 47% of nitrogen, sometimes - 1% less. Outwardly it is snow-white granules. This fertilizer has an increased ability to acidify the soil, so it can be applied only with neutralizing agents - dolomite flour, chalk, lime. Urea is very rarely used as a primary fertilizer, it is usually used as an additional foliar fertilizer. It is an excellent foliar fertilizer also because it does not burn the leaf plates, but is well absorbed by plants.

There are two known brands of urea, which are called A and B. Grade A is not a highly effective grade and is very rarely used in crop production. Usually urea grade A is used as a feed additive for animals, such as goats, cows, horses. Urea grade with the name B - is treated with additives urea, used specifically as fertilizer.

Liquid nitrogen fertilizers

Ammonia Hydrate , or ammonium hydroxide (ammonia water or liquid ammonia). The chemical formula for ammonium hydroxide NH4OH. In fact, ammonia water is ammonia dissolved in water. There are two types of liquid ammonia, the first contains nitrogen at least 19% and no more than 26%, and the second can contain from 15% to 21% of nitrogen. Usually make the ammonia water by special equipment, capable of embedding this fertilizer in the soil at a depth of about 14-16 cm.

advantages of liquid fertilizers - it's an extremely low price, fast digestibility by plants, long life and even distribution of fertilizers in the soil. There are also disadvantages - it is quite difficult to transport and storage, the possibility of severe burns on the leaves when the fertilizer hits their surface and the need for special equipment designed for making liquid fertilizers.

Organic nitrogen fertilizers

As you know, nitrogen is present in organic compounds, but its quantity is small. For example, nitrogen in cattle manure does not exceed 2.6%. In poultry manure, which is quite toxic, it is up to 2.7%. Nitrogen is also present in compost, but the amount varies greatly depending on the "ingredients" of the compost. Compost made from lake silt, leaf litter, green mass of weeds and lowland peat contains the most nitrogen. Given the instability of the nitrogen content of organic fertilizer, its use as the main fertilizer is not desirable and threatens nutritional deficiencies and nitrogen starvation for plants. In addition, such fertilizers, although slowly, but still acidify the soil.

Nitrogen fertilizers
Organic nitrogen fertilizer

Cultures for which nitrogen is especially important

In general, every crop needs nitrogen, but the doses of application for certain crops are different. With this in mind, all plants can be grouped into categories according to their need for nitrogen.

The first categorycan include plants that need to be fertilized with nitrogen before planting them in the ground to activate growth and development. These crops require about 26-28 grams of nitrogen per square meter in terms of ammonium nitrate and per square meter of area. This category includes, of vegetable crops: potatoes, cabbage, bell peppers, eggplant, zucchini, pumpkin and rhubarb; of berry and fruit crops: plum, cherry, raspberry, blackberry and strawberry; of flower crops: lilac, rose, dahlia, peony, violet, phlox, balsam, clove, nasturtium and zinnia.

The second group are crops that need less nitrogen. Usually only 18-19 g of nitrogen in terms of ammonium nitrate and per square meter of area is sufficient. From vegetable crops this category can include: tomatoes, parsley, cucumber, carrots, corn, beets and garlic; from fruit and berry crops: apple trees, currants, gooseberries; from flower crops: all annuals and delphiniums.

The third category are plants that need nitrogen in moderate amounts, not more than 10-12 g per square meter in terms of ammonium nitrate. From vegetable crops this category may include: early maturing potatoes, salad crops, radishes and onions; from fruit crops it is pear; from flower crops: bulbs, primroses, mountain flower, rockflower and daisy.

The final category requires a minimum amount of nitrogen per square meter, not more than 5-6 g in terms of ammonium nitrate. From vegetable crops, spicy herbs and legumes can be included here; from floral crops, poppies, azaleas, milkweed, heathers, heather, ericaceae, portulaces, rhododendrons and cosmeas.

Rules for nitrogen fertilizers

Remember that only optimum doses of nitrogen fertilizers can have a positive effect on the growth and development of various crops, and fertilizers must be calculated on the basis of the percentage of nitrogen in the fertilizer, and applied according to the type of soil, season and plant.

For example, when applying nitrogen to the soil in autumn there is a risk of it being washed into the groundwater. Therefore, the most suitable period for the application of fertilizers containing nitrogen is precisely the spring.

If you plan to fertilize soils with increased acidity, be sure to mix nitrogen with various neutralizing acidifying components - chalk, lime, dolomite flour. Thus, and fertilizers will be absorbed better, and the soil will not be acidified.

Peoples of the steppe and steppe zone, where soils are mostly dry, it is very important to apply nitrogen fertilizer periodically, without abrupt interruptions, which may affect the plants in the form of delays in growth, development, reduced yields. The first feeding should preferably be carried out, using urea, and when the plants enter the active phase of vegetation - to apply ammonium nitrate.

The consequences of nitrogen deficiency

We have partially mentioned it, but not only in the suppression of growth manifests nitrogen deficiency. Quite often, it is also the case that the leaf blades of the plants begin to change color atypically, they turn yellow, and this is the first signal to apply fertiliser. When nitrogen deficiency is severe, in addition to the yellowing of the leaf plates, their tips slowly begin to dry out.

Nitrogen fertilizers
Signs of nitrogen deficiency on corn leaves. © Chad Lee

Can there be harm from nitrogen fertilizer?

Yes, there can be if there is an overabundance. Usually with an overabundance of nitrogen, the above-ground plant mass begins to develop too actively, the shoots thicken, the leaf plates increase, the internodes become larger. The green mass gets atypical lushness and softness, and flowering is either weak and short or does not come at all, therefore, no ovaries are formed and no fruits and berries are formed.

If nitrogen is too much, something like burns appears on the leaf plates, then such leaves die off and fall off early. The death of leaves sometimes leads to the partial death of the root system, so the nitrogen application must be strictly rationed.

Totals. So we understand that all plants need nitrogen fertilizers, but you need to correctly determine their dosages and apply in accordance with the recommended timing, relying, among others, on the properties of the fertilizers themselves.