Nitrogen fertilizers
In spring and in the first half of summer, plants need nitrogen – it is he who is responsible for growth and development. Therefore, at this time, nitrogen fertilizers are needed in the garden and vegetable garden. But they are different. Let’s find out what types exist and how to use them.

What is nitrogen fertilizer

These are fertilizers that contain significant amounts of nitrogen(1). It can be the only nutrient, or in some accompanying nutrients, but nitrogen in any case prevails.

Since nitrogen is very mobile in the soil, it is very often not enough for plants. Therefore, nitrogen fertilizers are one of the main ones.

The Importance of Nitrogen Fertilizers

Nitrogen fertilizers have several important functions.

Enhance plant growth. Nitrogen is a part of DNA, RNA and proteins, that is, in every “brick” from which a plant is built, there is nitrogen. If nitrogen is in abundance, plants quickly gain weight.

Increase productivity. It is generally accepted that nitrogen is responsible for growth, phosphorus for flowering, and potassium for fruiting. In general, this is true. But nitrogen also plays an important role in crop formation: it increases the size of not only shoots and leaves, but also flowers and fruits. And the larger the fruit, the higher the yield. Moreover, this element increases not only the size of vegetables and fruits, but also their quality. And thanks to nitrogen, flower buds are laid. The more of them, the more fruits.

Heals wounds on trees. Often after pruning, especially after a strong one, the places of cuts and cuts do not heal for a long time. As a result, the winter hardiness of plants decreases: heavily pruned trees can freeze slightly in winter. And on the frozen wood, black cancer and other diseases immediately “sit down”. This is when there is not enough nitrogen. Therefore, after pruning, the garden must be fed with nitrogen:

  • the first top dressing is done in April: 0,5 buckets of rotted manure or 1 – 2 kg of chicken manure per 1 sq. m near the trunk circle;
  • the second – in early June: the same fertilizers in the same doses.

Instead of organics, you can use mineral fertilizers – ammophoska or ammonium nitrate (according to the instructions).

Accelerate fruiting. It happens that apple trees or pears sit on the site for years, actively grow up and down, but do not want to bloom. Five, seven, ten years pass, and still there is no harvest. Nitrogen fertilizers will help correct the situation. To speed up the flowering of apple and pear trees, they must be applied twice:

  • the first – at the beginning of shoot growth: 40 – 50 g per trunk circle of a young apple tree;
  • the second – before the end of shoot growth (at the end of June): 80 – 120 g per trunk circle.

Suitable ammonium nitrate or urea. But remember: this is a very high dose and it is impossible to apply such an amount of fertilizer to dry land! It must first be watered, then fertilized, and then watered again.

Types and names of nitrogen fertilizers

Nitrogen fertilizers are divided into 2 groups:

  • organic;
  • mineral.

The first group includes manure and its derivatives (mullein infusion, humus, and others). But mineral nitrogen fertilizers, in turn, are divided into 4 groups:

  • amide (urea);
  • ammonia (ammonium sulfate, ammonium chloride, ammonium carbonate, ammonium sulfide);
  • ammonium nitrate (ammonium nitrate);
  • nitrate (sodium nitrate, calcium nitrate, potassium nitrate).

Application of nitrogen fertilizers

Nitrogen fertilizers, as a rule, are used from early spring to the end of July – they cannot be applied later, because they provoke the growth of green mass, on which plants spend all their strength to the detriment of the harvest. And in trees near shrubs, late application of nitrogen delays the growth of shoots, they do not have time to mature, which reduces the frost resistance of trees (2).

The exception is fresh manure. It is applied in the fall as it is very concentrated and can burn the roots. And over the winter, it partially decomposes and becomes safe for plants.

Nitrogen fertilizers can be used as the main fertilizer – applied in the spring for digging, as top dressing in the summer – with irrigation, and some mineral – for foliar top dressing on the leaves.

Pros and cons of nitrogen fertilizers

Nitrogen fertilizers are very diverse, each of them has its own specific pros and cons, but there are also common points.

Pros

Well soluble in water. Most nitrogen fertilizers dissolve readily in water, so they can be used as top dressing with irrigation or as a foliar top dressing for foliar spraying.

They are quickly absorbed by plants. The effect of their application comes very quickly – in just a few days.

Cons

If nitrogen fertilizers are used correctly, according to the instructions, then there are no problems with them. But if the plants are overfed with nitrogen, the consequences can be unpleasant.

Plants are fattening. This is especially noticeable on fruit vegetables – cucumbers, tomatoes and more. They go to the leaves, but there are no fruits. It also fats potatoes – it does not form tubers.

Fruit, berry and perennials freeze slightly. If in the second half of the summer you overfed the plants with nitrogen, it is likely that they will freeze slightly. Even in mild winters.

The decrease in winter hardiness is associated with a high water content in the shoots. So it’s better not to joke with nitrogen – you must comply with both doses and terms.

Fruits, tubers and bulbs are stored worse. Overfed potatoes and apples will not lie for a long time – they will quickly rot.

Plants are more susceptible to diseases and pests. If there are two plants in the garden – one fertilized according to the rules, and the second overfed, then, for example, aphids and powdery mildew will attack the overfed plant first.

Nitrates accumulate in fruits and greens. This is especially true if the plant does not have enough light. For example, vegetables are planted under trees.

By the way, nitrates, which constantly scare us, are not so dangerous. Much more dangerous than nitrite. At very high doses of nitrogen, nitrosamines also accumulate in plants, and these are carcinogens.

The use of nitrogen fertilizers in the garden and vegetable garden

In the garden, mineral nitrogen fertilizers are usually applied in early spring – at the beginning of bud break. If the area under the trees is empty, there is just earth, then they are evenly scattered in near-stem circles and embedded in the soil with a rake. If there is a lawn or turf under the trees, they are simply scattered over the surface.

In the garden, mineral nitrogen fertilizers are also applied in the spring, for digging the site. In the future, they are used as dressings – they are dissolved in water and watered over vegetables. Or they are sprayed on the leaves if the plants show clear signs of a lack of nitrogen.

Fresh manure both in the garden and in the garden is brought in in the fall for digging (with the exception of gardens with a lawn or turf – they do not use manure there). Humus can be added to the holes immediately before planting or used as mulch for beds and trunks of trees and shrubs.

It is important to remember that nitrogen fertilizers are most effective in moist soil(3).

Popular questions and answers

We addressed the most popular questions about nitrogen fertilizers agronomist-breeder Svetlana Mikhailova.

Is it possible to apply nitrogen fertilizers in the fall?

Nitrogen fertilizers are very mobile – they are quickly washed into the lower layers of the soil with rain and melt water, and from there the plants cannot get them. Therefore, nitrogen fertilizers are not applied in autumn – this is a meaningless exercise. The only exception is fresh manure – it takes time to decompose, and winter is usually enough for this.

Can nitrogen fertilizers be used for indoor plants?

It’s not just possible – it’s necessary, because they also grow, they also need nitrogen. But here it is important to choose the right fertilizers. It is better not to use mineral ones – their doses are always indicated for a large area, at least 1 sq. m, but how to translate this dose into the volume of the pot? And if the dose is exceeded, the roots can burn.

 

For indoor plants, it is better to use liquid organic fertilizers.

Is it true that nitrogen fertilizers accumulate nitrates?

Yes, nitrates are derivatives of nitrogen. However, they accumulate only if fertilizers are used incorrectly, for example, they exceed the dose.

 

By the way, many summer residents believe that nitrates accumulate in vegetables and fruits only when mineral nitrogen fertilizers are used. This is not true – they also accumulate from manure and even more often.

Sources of

  1. Kovalev N.D., Atroshenko M.D., Deconnor A.V., Litvinenko A.N. Fundamentals of agriculture and crop production // M., Selkhozizdat, 1663 – 567 p.
  2. Rubin S.S. Fertilizer of fruit and berry crops // M., “Kolos”, 1974 – 224 p.
  3. Ulyanova M.A., Vasilenko V.I., Zvolinsky V.P. The role of nitrogen fertilizers in modern agriculture // Science, technology and education, 2016 https://cyberleninka.ru/article/n/rol-azotnyh-udobreniy-v-sovremennom-selskom-hozyaystve

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