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Types and Uses of Nitrogen Fertilizers for Crop Production

Published:

September 3, 2024

Key Takeaways:

Nitrogen fertilizer is a necessity in most cases, but must be treated with care.
Monitor your soil closely, and only add as much fertilizer as is necessary for each specific crop.
Try to use natural fertilizers as your primary source of nitrogen, while saving synthetic options as "quick fix" options when needed.
Always be aware of the possibility of nitrogen escaping into the water, or the atmosphere, and mitigate this as possible.

Nitrogen is one of the basic substances needed for life on Earth. While nitrogen gas (N2) is plentiful in the atmosphere — making up approximately 78% of the air we breathe — most plants are unable to take nitrogen directly from the air. They must instead pull it from the soil, depleting the soil in the process.

This makes nitrogen-based fertilizers one of the single most important additives in modern farming. However, N fertilizers cannot be used mindlessly. Using the wrong type of fertilizer, or too much of it, can cause serious problems for your crops and your land overall.

Cropler wants to make farming easier through modern technology, and improved fertilization is a big part of that. So let's discuss fertilizers with nitrogen, and how to safely use them to improve your fields and harvests.

What Are Nitrogen Fertilizers?

N fertilizers are simply additives, in either solid or liquid form, that add nitrogen to the soil. They may come as part of a more comprehensive fertilizer that also includes compounds such as phosphates and potassium, or they may only add nitrogen.

The Three Forms of Nitrogen Fertilizer

Regardless of whether the source is organic or synthetic, nitrogen fertilizers come in three types: Nitrate, Ammonia/Ammonium, and Urea.

Nitrate (NO3) Fertilizers. Nitrate fertilizers dissolve readily in water and do not bind to substrate particles. This should make them a good choice for ensuring plants have access to the nitrogen they need. However, that dissolvability is a two-edged sword. This means that nitrite fertilizers are easily displaced by rainfall, and can sink deep into the ground beyond the reach of plants' roots. Or, in dry times, the water may evaporate, allowing the nitrogen to turn into a gas and escape back into the atmosphere. In worst case scenarios, nitrates may even wash away into local rivers or other water sources, creating pollution.
Ammonia (NH3) or Ammonium (NH4). Ammonia and Ammonium can become nitrites through the actions of soil microorganisms, a process called nitrification. Therefore, it's another viable option for providing nitrogen to crops. Further, NH3 ammonia will be converted into ammonium by water within the soil, so it becomes ammonium fertilizer one way or another. Unlike pure nitrates, ammonia-based fertilizers will bind to many materials in soil, such as clay and organic byproducts. This reduces the chances of the nitrogen leaching away. Be aware: chemical reactions going on within bioactive soil will still strip the nitrogen out, turning it back into gas and opening up the possibility of it escaping into the atmosphere.
Urea (CH4N2O). Urea — a component in many types of urine — can also be used as an N source. However, this requires a three stage process within the soil: 
- Soil enzymes process the urea into ammonia 
- The ammonia is converted into ammonium by water in the soil 
- Chemical reactions in the soil convert the ammonium into nitrogen 
If the urea fails to go through all three stages, it fails as nitrogen fertilizer. In addition, being water-soluble, it may leach. Fortunately, these processes are relatively quick, taking 3-4 days on average. In all cases, close monitoring of the soil is necessary for proper use of farm nitrogen fertilizer. Soils with high pH values (around 7) in warm weather will be most conducive to turning ammonium into nitrogen. Low pH values (below 5.5) and colder temperatures inhibit this process. Nitrification needs to be controlled so that the nitrates don't evaporate or leach away too quickly, while still being available to the plants' roots.

Organic vs Synthetic Nitrogen Fertilizers

Nitrogen fertilizers can be divided up into two broad types, natural or synthetic. Natural N fertilizers are derived from nitrogen-rich substances such as manure, fish emulsions, or compost. Synthetic fertilizers are created in a lab by using N2 gas and transforming it into solid or liquid forms.

The discussion over natural vs synthetic fertilizers is complicated, and we've covered it previously in more detail. To summarize:

Natural fertilizers tend to be more expensive and more labor-intensive. In addition, they take longer to work. However, they have been repeatedly shown to be much better for long-term soil health, as well as reducing environmental pollution.

Synthetic fertilizers are cheaper and faster, but that fast action comes at a cost. They tend to increase soil pH levels, and can also harm the soil's natural biological processes. Synthetic fertilizers can be life-savers if a planting suffers from lack of nutrients, but overuse will cause long-term harm.

Using Nitrogen Fertilizers

The amount, timing, and placement of nitrogen-based fertilizers will vary greatly depending on the crop. Wheat has very different requirements than tomatoes. As a few broad guidelines:

How much: Base this on soil samples. Take samples ranging from topsoil down to the maximum depth of the roots. Then compare that against the crop's need for nitrogen to determine amounts.
When to apply: Nitrogen fertilizers should typically be applied during the growing process, rather than pre-applied, based on the plants' health. Also, never apply nitrogen fertilizers during heavy rain or when heavy rain is expected; it'll wash away before reaching the roots.
Placement: In general, N fertilizers should be injected into the ground, near the roots, to guarantee uptake. However, some dry pellet forms of N fertilizer are intended to be placed at ground level and will slowly percolate into the ground—if they don't wash away.

Precautions When Using Nitrogen in Fertilizers

Fundamentally, nitrogen fertilizers are a necessity for most high-yield farmed crops. They boost plant health and yield, and you have numerous product options based on delivery methods and amounts.

However, there are drawbacks and dangers involved in nitrogen fertilizers which must be addressed:

Root shock. Too much nitrogen delivered too close to the roots can scorch them, damaging the plants.
Soil acidity. Nitrogen fertilizer use, especially synthetic fertilizer, will increase the acidity of the soil and harm the soil's microbiome.
Water contamination. If excessive nitrogen is leached from the soil via rains or other movement, the fertilizer can make its way into local water sources.
Atmospheric contamination. Nitrogen dioxide is a greenhouse gas, and will be produced by nitrogen fertilizers escaping into the atmosphere. Collectively, this is likely contributing to global climate change.

As an aside, planting legumes as a rotational crop can help here. Unlike other plants, legumes can fix nitrogen directly from the atmosphere, and will ultimately contribute nitrogen to the soil. So, legumes can reduce your reliance on nitrogen fertilizers.

When you have questions, we'll help you find the answers you need to take control of your fields and the harvest you care about. Contact Cropler to discover more about our products and the ways we help you proactively protect your operations from the effects of crop diseases. Discover More

In Summary

Cropler can make monitoring your fields easier! Our high-tech combination of weather-proofed agri-cameras with an easy-to-use web platform allows you to visually oversee your farm from anywhere. And coming soon are soil monitors which, combined, will provide even easier access to the data you need to optimize your yields, year after year.