Crop yield and quality of agricultural products directly depend on adequate mineral nutrition, where nitrogen plays a key role.
It is one of the main elements necessary for plant growth, the formation of proteins, enzymes, and chlorophyll. Regardless of crop or region, effective application of nitrogen fertilizers not only increases yield but also enables the rational use of farm resources.
Against the backdrop of climate change, soil depletion, and rising production costs, choosing the correct form and dose of nitrogen becomes critically important.
Nitrogen Fertilizers: What Are They?
Nitrogen fertilizers are mineral compounds that contain nitrogen in a form available for plant uptake. They are applied to improve soil fertility and ensure full growth of agricultural crops.
The main feature of nitrogen fertilizers is that they supply one of the most important nutrients—nitrogen, which participates in the synthesis of proteins, enzymes, chlorophyll, and other biologically active substances.
Nitrogen in fertilizers can be present in three main forms: ammonium (NH₄⁺), nitrate (NO₃⁻), and amide (NH₂). Each has its own properties: the ammonium form is better retained in the soil, the nitrate is quickly absorbed by plants, and the amide requires enzymatic conversion.
In terms of physical form, nitrogen fertilizers come as solids (granules, powders) and liquids (e.g., UAN solution). Using nitrogen fertilizers can significantly increase yield but requires precise dosing, as excess nitrogen leads to excessive vegetative growth, reduced product quality, and environmental pollution risks.
Importance of Nitrogen Fertilizers for Plants
Nitrogen is a key nutrient element without which full plant development is impossible. It is part of amino acids, from which proteins are formed, and is the basis of nucleic acids (DNA and RNA), enzymes, and chlorophyll—the main photosynthesis pigment.
Nitrogen stimulates vegetative growth, is responsible for photosynthesis intensity, and the formation of new cells and tissues. In cereals, it contributes to the formation of a full ear and increases grain protein content; in industrial crops, it raises sugar, starch, or oil content depending on the crop.
Nitrogen deficiency first appears on older leaves: they yellow, lose turgor, growth slows, leaf area reduces, and yield drops by tens of percent. In fruit crops, nitrogen deficiency worsens fruit set and yield size. At the same time, excess nitrogen is equally harmful.
It causes excessive green mass buildup, suppresses root system and generative organ development (flowers, fruits), prolongs vegetation, reduces winter hardiness, and worsens product quality. Moreover, high doses lead to nitrate accumulation, especially in leafy vegetables.
Types of Nitrogen Fertilizers
Nitrogen is one of the key elements without which it is impossible to achieve a stable and quality yield. Its participation in the synthesis of proteins, chlorophyll, and growth regulation makes nitrogen fertilizers the foundation of nutrition for most agricultural crops.
However, the effectiveness of such fertilizers depends not only on their composition but also on application conditions, soil type, and crop characteristics. Incorrect dosing or form of nitrogen can not only reduce results but also cause nutrient losses and environmental harm. To avoid mistakes, it is important to understand what types of nitrogen fertilizers exist, how they differ, and how to use them correctly.
Urea (Carbamide)
Urea (carbamide) is one of the most common and effective nitrogen fertilizers, containing about 46% nitrogen in the amide form. Thanks to its high nitrogen concentration, urea provides intensive plant nutrition, promoting rapid leaf and green mass growth.
Application of urea increases crop yields and improves product quality, especially in cereals and vegetable crops. The fertilizer is highly soluble in water, allowing its use both in dry form and in solutions for foliar feeding.
However, when applying urea, one must consider the risk of nitrogen losses as ammonia, especially with surface application without incorporation into the soil. Therefore, it is important to follow optimal agronomic practices to ensure maximum nitrogen uptake by plants and minimize environmental risks.
Ammonium Nitrate
Ammonium nitrate is a highly concentrated nitrogen fertilizer containing about 34% nitrogen, half in the ammonium form and the other half as nitrates. This dual form provides plants with both quick-acting nutrition from nitrates and longer-term nitrogen supply via the ammonium form.
Ammonium nitrate dissolves well in water and is rapidly absorbed by roots, making it effective in various climatic conditions and for different crops. Thanks to its balanced composition, it is often used to fertilize cereals, industrial crops, vegetables, and fruit-berry plantations.
An important advantage of ammonium nitrate is its storage stability and ease of transport. However, correct application is essential, as excessive use or agronomic errors can lead to nitrogen losses through leaching or ammonia volatilization.
Sodium Nitrate
Sodium nitrate is a nitrogen fertilizer containing about 16% nitrogen in nitrate form and approximately 26% sodium. Due to its chemical composition, the nitrogen in sodium nitrate is quickly taken up by plants, providing rapid nutrition during active growth and development.
It is important to note that the sodium content affects soil physicochemical properties—this fertilizer is better suited for acidic and slightly acidic soils where sodium does not accumulate to harmful levels.
For crops that respond positively to sodium, such as sugar beets, using sodium nitrate can boost yields by partially replacing potassium. However, it should be avoided on alkaline or saline soils, as excess sodium can harm soil structure and root development.
Sodium nitrate also dissolves well in water, making it convenient for both dry application and foliar feeding solutions. Because of its rapid effect, it is mainly used in spring–summer when plant nitrogen demand is highest, and is often included in mixed or complex fertilization systems to optimize crop nutrition.
Ammonium Sulfate
Ammonium sulfate is one of the most common nitrogen fertilizers, combining ammonium nitrogen with sulfur in sulfate form. It is widely used due to its high uptake efficiency and the additional supply of sulfur—a vital element for crop growth and development. This fertilizer is especially beneficial on acidic to neutral soils, as sulfur helps acidify the soil and improves nutrient availability.
Ammonium sulfate has high water solubility, ensuring rapid delivery of nitrogen and sulfur to plants. It is used for both base fertilization and top-dressing of growing crops. The fertilizer enhances protein metabolism in plants, increasing yield and product quality.
Besides agronomic benefits, ammonium sulfate is stable in storage, moderately priced, and poses minimal environmental risk when used properly. However, excessive application can acidify the soil, so adherence to recommended rates and timing is crucial.
Calcium Nitrate
Calcium nitrate is a water-soluble fertilizer containing nitrate nitrogen and calcium. It is widely used to supply plants with not only nitrogen but also calcium—a key element for cell wall formation and tissue strength. The nitrate nitrogen is quickly absorbed, stimulating foliage growth, while calcium enhances disease resistance and fruit quality.
Calcium nitrate is especially valuable for calcium-sensitive crops like tomatoes, peppers, apples, and grapes. Its application helps prevent blossom end rot, tissue deformities, and yield losses. Due to its high solubility, it is well suited for foliar feeding and drip irrigation.
Proper use of calcium nitrate involves following recommended rates and timely feeding during active growth periods, ensuring both adequate nutrition and improved yield and quality of agricultural products.
Potassium Nitrate
Potassium nitrate is a compound nitrogen–potassium fertilizer containing a high concentration of nitrate nitrogen and potassium in nitrate form. It combines nutrients necessary for vigorous plant growth and the formation of a high-quality yield. Nitrate nitrogen is quickly absorbed by plants, promoting vegetative growth, while potassium increases crop resistance to drought, diseases, and frost.
This fertilizer is widely used for feeding vegetable and fruit crops, as well as cereals, especially on soils with low potassium content. Potassium nitrate enhances water balance in plants, regulates metabolism, and improves product quality, including taste and storage life.
Application of potassium nitrate is recommended during periods of active growth when plant nutrient demand is highest. Proper use of this fertilizer helps optimize plant nutrition, boost immunity, and ensure consistently high yields.
Basic Rules for Applying Nitrogen Fertilizers
Correct application of nitrogen fertilizers is a key factor in achieving high productivity of agricultural crops and maintaining soil fertility. For fertilizers to be effective, one must consider crop characteristics, soil type, weather conditions, and agronomic practices.
Failure to follow these rules can lead to reduced yields, environmental pollution, and economic losses. The main principles for applying nitrogen fertilizers include:
- Timely application of fertilizers during periods of highest plant nitrogen demand;
- Adherence to recommended application rates according to soil type and crop;
- Splitting the total dose into multiple applications throughout the growing season to improve uptake;
- Avoid applying fertilizers immediately before expected rainfall to reduce losses;
- Combining nitrogen fertilizers with other mineral nutrients for balanced feeding.
Following these rules allows optimization of nitrogen use, increased fertilization efficiency, and minimized environmental impact. Such an approach is the foundation of a stable and quality harvest.
Timing and Rates of Nitrogen Fertilizer Application
Timing and rates of nitrogen fertilizer application are critical for effective plant nutrition and environmental safety. Nitrogen should be applied in accordance with crop growth stages, as excess at early stages can lead to volatilization losses, and deficiency to slowed plant development.
Typically, main top-dressings are performed during periods of intensive vegetative growth when nitrogen demand is highest.
Rates depend on soil type, crop, and agrochemical status of the field. For example, light sandy soils require lower doses to avoid leaching, while heavy loams can retain more nutrients. On average, nitrogen rates range from 50 to 150 kg N/ha, depending on crop and production goals.
Weather conditions must be taken into account: applying nitrogen before rain increases leaching risk, while during dry periods fertilizers may be unavailable to plants. Therefore, splitting doses over several feedings during the season enhances fertilizer use efficiency and reduces environmental impact.
Key points to consider when applying nitrogen fertilizers:
- Timeliness: apply during active growth phases;
- Application rates: based on soil type, crop, and agrochemical conditions;
- Split applications: several times during the season;
- Weather considerations: avoid before heavy rain or in drought;
- Balance nutrients to maintain soil fertility and environmental safety.
Following recommended timings and rates ensures not only high yields but also preservation of soil fertility and reduction of water resource contamination.
Conclusion
Nitrogen fertilizers are a key component of plant nutrition, ensuring vigorous growth and development. The variety of nitrogen fertilizer types allows selecting the optimal option for specific soil–climate conditions and crop types, enhancing agricultural efficiency.
However, their proper application is equally important to avoid nutrient losses and maintain ecological balance. Therefore, every farmer must consider all aspects to achieve maximum efficiency and minimize environmental impact.
