What Is Nitrogen Fertilizer? Common Types of Nitrogen Fertilizer and How to Identify Them

What is nitrogen fertilizer? Nitrogen fertilizer is a type of fertilizer, and it is the main fertilizer that promotes the growth of flowers' roots, stems, and leaves. The nitrogen it contains plays a very important role in crop growth. Applying nitrogen fertilizer can not only increase the yield of agricultural products but also improve their quality. What are the common nitrogen fertilizers? What methods are there for identifying nitrogen fertilizer? Let's take a look below.

What nitrogen fertilizer is

Nitrogen fertilizer is a chemical fertilizer containing the crop nutrient element nitrogen. Elemental nitrogen plays a very important role in crop growth: it is a component of amino acids in plants, a component of proteins, and also a component of chlorophyll, which plays a decisive role in plant photosynthesis. Nitrogen can also help crops propagate. Applying nitrogen fertilizer can not only increase the yield of agricultural products but also improve their quality. Nitrogen fertilizer is also a type of inorganic salt.

Common nitrogen fertilizer brands

Sinochem

Yihua

Kingenta

STANLEY

YF

Yuntianhua

LUXI

WF

Batian

Garsonly

The role of nitrogen fertilizer

Nitrogen fertilizer is a chemical fertilizer containing the crop nutrient element nitrogen. The main roles of nitrogen fertilizer are: increasing total biomass and economic yield; improving the nutritional value of agricultural products, especially increasing the protein content in seeds and improving the nutritional value of food.

Nitrogen is the main component of protein in crops. Without nitrogen, protein cannot be formed, and without protein, various life phenomena would be impossible. In crops, parts that contain more protein (such as seeds) also contain more nitrogen; parts that contain less protein (such as senescent stems) also contain less nitrogen. Moreover, nitrogen is also a component of chlorophyll and many enzymes. Chlorophyll is a substance necessary for crops to carry out photosynthesis, and enzymes are catalysts for the transformation of various substances in crops. Nucleoproteins and plant alkaloids also contain nitrogen. From this, it can be seen that nitrogen plays an extremely important role in crop nutrition. Crops begin to absorb nitrogen after the first true leaf appears.

When nitrogen fertilizer is applied insufficiently, crops generally show the following: plants are short and thin; leaves are yellow-green, yellow-orange, and other abnormal colors, and basal leaves gradually dry up and wither; roots have few branches; tillering of cereal crops is significantly reduced, or even absent, young ear differentiation is poor, branching is few, ears are small, crops show obvious premature aging and early maturity, and yield decreases.

When nitrogen fertilizer is applied excessively, crops generally show the following: growth is overly luxuriant, axillary buds keep emerging, tillering is often excessive, normal development of reproductive organs is hindered, and maturity is even delayed; leaves are dark green, stems and leaves are tender and juicy, the content of soluble non-protein nitrogen in the plant is too high, making it susceptible to pests and diseases and prone to lodging; grains of cereal crops are not plump (low 1000-grain weight), with many empty grains, and crop yield decreases.

The nitrogen fertilizer commonly used now is mainly urea. Urea is an organic nitrogen fertilizer. It can only be absorbed and utilized by crops after being hydrolyzed into ammonium carbonate or ammonium bicarbonate through urease reactions in the soil. Therefore, urea should be applied 4 to 8 days before the crop's fertilizer-demand period. It should also be applied deeply and covered with soil. The final product of urea decomposition in soil is ammonium carbonate, which is very unstable and decomposes in the soil or on the soil surface to form free ammonia, which is easily lost through volatilization. Like other nitrogen fertilizers, urea should be applied in the morning or evening, preferably after rain or on cloudy days, and application at noon on sunny days should be avoided. Urea is a single-element fertilizer, so it should be used together with phosphate fertilizer or other chemical fertilizers. This can not only meet the crop's needs for various nutrients but also give play to the synergistic effect between fertilizers.

The development of nitrogen fertilizer

Since the 20th century, the production of nitrogen fertilizer has held a pivotal position. This is mainly because the average nitrogen fertility of soils worldwide is not high, nitrogen is not easily accumulated in soil, and modern intensive agriculture promotes excessive loss of soil organic matter and nitrogen. Under most conditions, the yield increase per unit of nitrogen is higher than that of phosphorus and potassium nutrients.

China's nitrogen fertilizer industry developed relatively late. It was not until 1935 that two nitrogen fertilizer plants were successively built in Dalian and Nanjing to produce ammonium sulfate. Before 1949, the cumulative national production of nitrogen fertilizer was 600,000 tons (N), mainly used in the coastal provinces. After the founding of New China, the nitrogen fertilizer industry developed rapidly before phosphorus and potassium fertilizers. In 1953, China's annual nitrogen fertilizer output, calculated as nutrients, was 50,000 tons, exceeding the highest historical annual output of 48,000 tons in 1941. After the first and second Five-Year Plans for National Economic Development, by 1965, the national nitrogen fertilizer output had reached 1.037 million tons (N), nearly 10 times that of 1953. Later, after the 10-year period of major development from 1969 to 1978 in which large, medium, and small fertilizer plants were developed simultaneously, more than 1,000 small nitrogen fertilizer plants and more than 10 large nitrogen fertilizer plants with an annual output of 300,000 tons of synthetic ammonia were newly built nationwide. By 1983, the national nitrogen fertilizer output had soared to 11.094 million tons (N), making China the world's second-largest nitrogen fertilizer producer after the former Soviet Union. In 1991, the national nitrogen fertilizer output reached 15.100 million tons, rising to first place in the world.

What are the common nitrogen fertilizers

Ammonium nitrogen fertilizers

Ammonium nitrogen fertilizers include ammonium bicarbonate (NH4HCO3), ammonium sulfate {(NH4)2SO4}, ammonium chloride (NH4Cl), ammonia water (NH3.H2O), liquid ammonia (NH3), and others.

Common characteristics of ammonium nitrogen fertilizers:

1. Ammonium nitrogen fertilizers are easily adsorbed by soil colloids, and some enter the crystal layers of clay minerals.

2. Ammonium nitrogen is easily oxidized into nitrate.

3. In alkaline environments, ammonia is easily lost through volatilization.

4. High concentrations of ammonium nitrogen can easily cause toxicity to crops.

5. Excessive absorption of ammonium nitrogen by crops has a certain inhibitory effect on the absorption of calcium, magnesium, and potassium.

Nitrate nitrogen fertilizers

Nitrate nitrogen fertilizers include sodium nitrate (NaNO3), calcium nitrate {Ca(NO3)2}, ammonium nitrate (NH4NO3), and others.

Common characteristics of nitrate nitrogen:

1. Easily soluble in water and moves relatively quickly in soil.

2. NO3— is mainly absorbed, and crops easily absorb nitrate.

3. Nitrate fertilizers have no inhibitory effect on crop absorption of nutrients such as calcium, magnesium, and potassium.

4. Nitrate is a negatively charged anion and cannot be adsorbed by soil colloids.

5. Nitrate is easily reduced to gaseous states (NO, N2O, N2) through denitrification and lost from the soil.

Amide nitrogen fertilizers

Urea: molecular formula CO(NH2)2, N content 44-46%. It is a high-quality solid fertilizer with the highest nitrogen content and is a chemically synthesized organic small-molecule compound. It is easily soluble in water, and its aqueous solution reacts neutrally; it easily deliquesces in high-temperature and humid environments. It is a physiologically neutral fertilizer. After application to soil, a small portion is absorbed in molecular form, and most is converted into (NH4)2CO3 through urease action and then absorbed. Its fertilizer effect is slower than NH4+—N and NO3-—N. When used as a topdressing, it should be applied 4-5 days in advance; it has no adverse reaction on soil. It can be used as a base fertilizer or topdressing, is not recommended as a seed fertilizer, and is most suitable as a foliar topdressing; it is suitable for various soils and crops. When applied to calcareous and alkaline soils, it should be applied deeply and covered with soil to prevent ammonia volatilization.

Long-acting nitrogen fertilizers

Also called slow-acting or slow-release nitrogen fertilizers, controlled-availability nitrogen fertilizers. These are fertilizers that are difficult to dissolve in water or difficult for microorganisms to decompose, and that slowly release nutrients in the soil.

Common characteristics of long-acting nitrogen fertilizers:

1. Low solubility, slow nutrient release, reducing losses from nitrogen leaching, volatilization, fixation, and denitrification.

2. Stable and long-lasting fertilizer effect, able to meet nitrogen supply throughout the crop's entire growth period.

3. Can be used in large amounts at one time, saving labor and effort.

Simple identification of nitrogen fertilizer

The most common counterfeit nitrogen fertilizers on the market, such as fake urea, generally occur in two situations: first, the contents of the entire bag are inconsistent. If the material at the upper opening of the packaging bag has good flowability, while the material below does not flow or even caking occurs, and a relatively strong volatile ammonia smell can be detected, then it can basically be judged that the upper part is urea and the lower part is falsely mixed ammonium bicarbonate. If both the upper and lower parts have good flowability, but the color and particle size of the granules are inconsistent, then it may be falsely mixed ammonium nitrate; the other situation is that the contents of the entire bag of fertilizer are consistent. Common counterfeit substances include granular ammonium nitrate and some macromolecular organic substances such as polyols. Although the particles, color, and solubility of the above substances are very similar to urea, the following methods can still be used to identify it.

Appearance

Urea is white, semi-transparent granules with no reflection on the surface; ammonium nitrate granules have obvious luster and reflection on the surface; polyols are opaque milky white granules with no luster and no reflection.

Feel

Urea is smooth, loose, and has no moist feeling; ammonium nitrate, although smooth, has a damp feeling; polyols, although loose and not damp, are not very smooth.

Burning

Place the three substances separately on red-hot charcoal or an iron plate. Urea melts, emits white smoke, and has an ammonia odor; ammonium nitrate burns violently, emits strong light and white smoke, and is accompanied by a “chi chi” sound; polyols decompose and burn, but have no ammonia odor.