Everything you need to know about the most important Fertilizer: Nitrogen Fertilizer

Nitrogen is always around plants, just like it is around us. That’s because nearly 80% of the air on Earth is nitrogen. But plants can’t use nitrogen in the atmosphere in its simple molecular form. It should be in the form of other compounds, such as ammonium nitrate, often used as a nitrogen fertilizer. Blood meal and manure, more complex organic fertilizers, are also good nitrogen sources. Nitrogen fertilizer is chemical fertilizer among different types of fertilizers.

Role of Nitrogen

 Nitrogen is one of the three nutrients that botanists and soil scientists consider to be primary nutrients. The other two are phosphorus and potassium. Plants also need smaller amounts of secondary nutrients and so-called micronutrients. Nitrogen is one of the primary nutrients in fertilizers, and plants need a lot of it. In fact, of the 16 essential plant nutrients, nitrogen is the one that plants need the most. 

Nitrogen is a vital part of how plants work. It is a crucial part of photosynthesis, the process by which plants make food from sunlight. Also, nitrogen is needed for plants to make proteins and for almost everything else that goes on in their bodies. Plants that don’t get enough nitrogen don’t grow well, and their leaves turn yellow.

Forms of Nitrogen Fertilizers

Most Fertilizers used to grow crops have nitrogen in one or more of these forms: nitrate, ammonia, ammonium, or urea. You can use different kinds of fertilizer when, where, and how according to their properties. Here is a short explanation of these four types of nitrogen, what they do, and when they should or shouldn’t be used. 

1.Nitrate (NO3) Form 

Nitrates “dissolve” in water, so they move around in the soil as water moves around in the soil. Rain will wash nitrates down through the soil profile, where they may end up in drains or tiles and be lost for farming. This is called “leaching,” the main way coarse-textured sandy soils lose nitrogen. Several researches have studied the leaching of nitrate form in soil.

During dry times, when the water leaves the soil through evaporation, nitrates can move upward and may build up at the soil’s surface. But once nitrates have been washed below the root zone, it is unlikely that they will move back up in large amounts, so they are thought to be lost to the crop. 

When soils get too wet, the organisms in the soil take the oxygen they need from the nitrates. This leaves nitrogen as a gas that goes up into the air. This is denitrification, the most common way fine-textured clay soils lose nitrogen. 

2.Forms of Ammonia (NH3) and Ammonium (NH4) 

Ammonia is a gas at room temperature and pressure, but it can be pressed down to become a liquid, like the nitrogen fertilizer anhydrous ammonia. When anhydrous is used, the ammonia in the soil reacts with the water and becomes ammonium. 

Ammonia in water, known as aqua ammonia, can easily escape into the air; therefore, when you use it as a nitrogen fertilizer, you must place it below the soil surface. 

Even though ammonium dissolves in water, it sticks easily to clay and organic matter particles, much like iron sticks to and stays on a magnet. This keeps it from washing away. Then, when it’s time for plants to grow, microorganisms in the soil change the ammonium into nitrate, the main form that plants use. The soil conditions that help this process called nitrification, the most are:

  • A soil pH of 7.
  • Moisture at 50% of the soil’s water-holding capacity.
  • A soil temperature of 80F.

Soil pH below 5.5, a waterlogged moisture condition, and a temperature under 40F. are unfavorable conditions.

nitrogen fertilizers

3. Urea (COCNH) Form 

Urea usually undergoes a three-step change before crops take it up:

  1. The soil or plant residue enzymes convert the urea N to ammonia N.
  2. The ammonia reacts with soil water and changes to an ammonium form.
  3. Soil microorganisms’ activity converts the ammonium form to nitrate N. 

Like nitrates, urea dissolves in soil water and moves with it. If it is not turned into ammonia and then ammonium, it can be lost through leaching. When the soil is moist and the temperature is suitable for plants to grow, the change to ammonia takes only 2 to 4 days. Even if it freezes, the process will continue, though it will take longer. Because of this, there aren’t a lot of leaching losses in the field.

When urea is spread on the soil’s surface, it turns into ammonia. Some of this ammonia will “volatilize,” or escape into the air. How much will depend on the number of soil conditions? You can expect to lose the most when the soil pH is above 7. The soil is dry and has a high temperature. On the other hand, urea applied below the soil’s surface quickly turns ammonia into ammonium, which can’t move with water or evaporate into the air.

Application Suggestion of Nitrogen Fertilizer

  1. Three of the four liquid nitrogen fertilizers—anhydrous ammonia, aqua ammonia, and low-pressure 37-41% N solutions—must be incorporated into the ground to stop ammonia (gaseous nitrogen) from escaping into the air. On the other hand, you can spread dry or solid fertilizers and liquids with 28–32% N on the surface. On sloped cropland, you should also mix them into the soil to keep them from washing away. 
  2. You can use ammonium sulfate, diammonium phosphate, anhydrous ammonia, aqua ammonia, and urea in the fall before planting corn, except on soils that don’t drain well or drain too well. You shouldn’t apply it until the temperature of the soil at a depth of 4 inches has dropped to at least 50F. 
  3. Ammonium and fertilizers that make ammonium will make the soil more acidic over time (lower the pH). Soil samples should be taken where these fertilizers are often used to see if limestone is needed.

Management of Nitrogen Fertilizers

According to research, 40 and 60% of the nitrogen put into cropping and grazing systems is usually lost to the environment. Changing how farming is done can cut down on these losses, boost productivity, and save money. 

Right Amount  

Using soil or plant tests to figure out how much nitrogen is available to plants. Apply the amount of nitrogen fertilizer based on the yield you want and how much nitrogen the crop or pasture needs over the growing season. 

Support decisions about fertilizer that are more timely and accurate by taking into account the soil’s moisture level and seasonal forecasts. 

Avoid putting on a lot of nitrogen in one application (never exceed recommended rates, split applications may be more effective and adjust rates according to rainfall and temperature). 

nitrogen fertilizers

Right Time

When you can, try to time how much nitrogen fertilizer you use with how much your crops and pastures need. When growth rates are high, people want crops and pastures the most. Don’t put nitrogen fertilizer on wet and warm soils (above 10°C). Don’t till the soil when it’s wet and also avoid overwatering.

Check a 7-day weather forecast to see if there is a chance that the soil will get too wet and, if so, delay applying nitrogen fertilizer. In the summer, don’t put urea fertilizer on the ground after watering because this could cause more water to evaporate. 

When turning long-term pasture into crops, keep the length of fallow as short as possible, especially in areas with a lot of rain and water crops. 

Please find out how plants get nitrogen and make it easier for them to get it by improving the health and nutrient status of the soil. Adding nitrogen to soils that aren’t good for plant growth won’t likely make them more productive and make you more money. 

Right Type

Avoid fertilizers that are made with nitrates because they are more prone to loss. Enhanced Efficiency Fertilisers, coated for slow release or with nitrification inhibitors, may better match the fertilizer supply and plant demand for soil nitrogen.

With the help of chemicals called “inhibitors,” nitrate leaching and ammonium volatilization can be stopped. But it is best to ask an expert for help when choosing inhibitors. You should mix in fertilizer at the top of raised beds or ridges to keep it from getting concentrated and lost in furrows and wet areas. 

Excess of Nitrogen Fertilizers

Having too much nitrogen in fertilizer can be just as bad as having too little. It can make the plant grow too much foliage, stopping it from flowering and making fruit. In addition to these harmful effects on the crop or plant, too much nitrogen can harm the environment. The extra nitrogen from fertilizers can get into groundwater or surface water when it rains. When this happens, nitrogen starts to hurt the environment. In surface waters, it makes algae and other annoying plants grow too much.

nitrogen fertilizers

(Also Read- Difference between soil fertility and productivity)


Nitrogen fertilizers are essential in ensuring an adequate supply of nutritious food though numerous factors affect soil fertility. However, careful management is necessary to keep N fertilizer in the form and area where it can be most effective for sustaining healthy plant growth. We must balance the enormous benefits of N fertilizer against the potentially disruptive environmental effects. It may occur when N travels into regions where it is not needed so you can also use DIY fertilizer for houseplants in order to minimise it’s use.

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