Nitrogen 101: Everything Farmers Need to Know About Nitrogen

This guide includes the following sections:

• What Is Nitrogen?

• What Does Nitrogen Do in a Plant?

• Synthetic Nitrogen Fertilizers for Crop Production

• Organic Nitrogen Fertilizers for Crop Production

• When to Apply Nitrogen

• Determining Nitrogen Rates

• Nitrogen Management Best Practices

• Buy Nitrogen at FBN^®

What Is Nitrogen?

Nitrogen is a chemical element that makes up 78% of the Earth’s atmosphere and forms a part of all living tissue. In terms of crop production, nitrogen is one of the three primary macronutrients required by all plants for healthy growth and development. 

Nitrogen is generally included in all balanced crop nutrition programs. It exists in several forms for agricultural production, influencing application timing, cost, and management requirements. Understanding its role, forms, and management practices can help you optimize yield and profit potential while limiting negative environmental impacts. 

Want to know more about what it takes to feed your crop? Check out Crop Nutrition 101.

What Does Nitrogen Do in a Plant?

Nitrogen is often considered the foundational nutrient of crop production. Here are some essential functions that it performs:

• Component of amino acids: Amino acids are the building block of plant proteins and enzymes that carry out critical plant functions, including photosynthesis, hormone regulation, and nutrient transport.

• Component of chlorophyll: Chlorophyll molecules capture sunlight to drive plant photosynthesis and, ultimately, crop yield. 

• Nutrient balance: Adequate plant nitrogen helps crops take up other essential nutrients more effectively. 

• Improved agronomics: Sufficient plant nitrogen improves crop agronomics, including root development, stalk integrity, and biomass production.

Synthetic Nitrogen Fertilizers for Crop Production

With the exception of legume crops, most plants can’t fix atmospheric nitrogen and instead rely on synthetic or organic fertilizers to meet crop nutrient needs. There are several synthetic nitrogen fertilizer sources, each requiring slightly different management approaches. Basic information about the most common nitrogen fertilizers is included below.

Pros vs. Cons of Ammonium Nitrate | NH₄NO₃

Ammonium nitrate is a dry fertilizer that contains two forms of plant-available nitrogen, NH₄ and NO₃. It typically contains 34% nitrogen by weight and is broadcast as a soil application.

Pros: 

• Low volatilization losses compared to other N sources

• Very plant-available form for fast plant uptake

Cons:

• Long-time use can reduce soil pH

• Higher risk of leaching and denitrification than other NH₄ fertilizers

• Very hygroscopic, requiring special care for handling and storage

Pros vs. Cons of Anhydrous Ammonia | NH₃

Anhydrous ammonia is an efficient and widely used compressed liquid nitrogen fertilizer. It contains 82% nitrogen by weight and is applied using special pressurized application equipment. 

Pros: 

• Contains high nitrogen content; highly efficient nitrogen source

• Cost-effective nitrogen source

• Readily available

• Excellent option for fall applications

Cons:

• Can only be applied via soil injection to prevent nitrogen loss to the air as a gas

• Requires special equipment for application

• Significantly increased safety risks for handling and application

• May injure emerging crops when applied near planting time

• Not ideal for heavy-textured soils

• Can have negative impacts on soil microbes

Pros vs. Cons of Urea 

Urea is a dry-solid nitrogen fertilizer that contains approximately 46% nitrogen by weight.  

Pros: 

• Relatively high nitrogen content

• Excellent adaptability for fall, spring, and sidedress applications

• Can be applied as a solid, solution, or foliar spray for some crops

• Cost-effective and efficient form of nitrogen

• Reduces handling, storage, and transportation costs over other dry N forms

Cons:

• May be prone to surface volatilization; generally requires soil incorporation to limit loss

• Can contribute to soil acidification if used over time

Pros vs. Cons of Urea Ammonium Nitrate | UAN

UAN is a liquid urea and ammonium nitrate solution that typically contains 28–32% nitrogen. 

Pros: 

• Liquid source of nitrogen that can be mixed with other crop protection products and fertilizers to add application efficiencies 

• Safe and easy to handle

Cons:

• May be prone to surface volatilization; generally requires soil incorporation to limit loss

• Not recommended for fall applications due to rapid nitrification

Phosphorus fertilizers like diammonium phosphate (DAP) and monoammonium phosphate (MAP) also contain significant nitrogen levels, varying between 11% and 18%. These products are a popular choice for farmers looking for a phosphorus and nitrogen source in one.   

As well, sulfur fertilizers like ammonium thiosulfate contain significant nitrogen levels.

Organic Nitrogen Fertilizers for Crop Production

Plants may also receive nitrogen from organic sources, including:

• Manure

• Soil organic matter

• Crop residue or cover crops

• Fixed atmospheric nitrogen

• Compost   

Organic nitrogen sources typically take longer to mineralize into plant-available forms crops can take up. They may also have more inconsistent nutrient content that requires synthetic fertilizer supplements to meet crop nutritional demands. One advantage is that they may help improve soil health, including physical and biological characteristics. 

When to Apply Nitrogen

Nitrogen application timing will depend on several factors, including:

• Crop type

• Nitrogen source used

• Environmental conditions

Applications can be made in the fall, spring, at-planting, or in-season as a sidedress application. Not all sources of nitrogen are suitable for all of these application timings. See the summary table below for more details about nitrogen sources and application timing in corn.

Applying nitrogen in the fall can reduce spring workloads, but there may be a greater risk of nitrogen loss without proper management. Some growers choose split applications, applying the season’s nitrogen over multiple applications, such as a pre-plant application in the spring followed by a sidedress application during the vegetative growth stages. 

Source: Purdue University Fertilization Agronomy Guide

 Learn how an in-season sidedress nitrogen application can benefit your crop.

Determining Nitrogen Rates

Determining nitrogen application rates may not be as simple as it was even a decade ago due to several factors, including:

• More access to variable-rate fertilizer technology

• Better seed genetics that improve nitrogen use efficiency

• Higher-yielding crops that may demand more fertility

• Dynamic fertilizer prices

• Changes in production practices, such as cover cropping and conservation tillage

Finding the most economical nitrogen rate will vary depending on yield goals, production practices, crop removal rates, and fertilizer prices. A nitrogen rate calculator can help determine the most profitable nitrogen rates depending on your application.  

Nitrogen Rate Calculations

Once you’ve determined the ideal nitrogen rate, it’s time to figure out how much fertilizer product to apply to reach those target rates. The calculations are relatively simple for dry nitrogen fertilizers measured by weight; however, the math gets a bit more tricky for liquid fertilizers, where volume and weight come into play. 

Example Dry Weight Fertilizer Calculation

Target nitrogen rate: 125 lbs/acre

Fertilizer analysis: 46-0-0 urea

Amount of fertilizer to apply: Target nitrogen rate/percentage weight of N in the fertilizer

Calculation: 125/0.46 = 271.7 or ~272 pounds of urea required to meet 125 lb N/acre goal

Example Liquid Fertilizer Calculation 

To determine the amount of liquid fertilizer, such as UAN, to apply, use the conversions in the table below to identify how many pounds per gallon your fertilizer source has. Anhydrous ammonia is a liquid when applied but quickly changes to gas. Therefore, to determine appropriate anhydrous rates, you can use the dry calculation formula mentioned above.

Target nitrogen rate: 125 lbs/acre

Fertilizer analysis: 28-0-0

Amount of fertilizer to apply: Target nitrogen rate/pounds N per gallon of fertilizer source

Calculation: 125 lbs/2.9 lbs N per gallon = 43 gallons UAN 28 applied to meet 125 lbs/acre goal

If you prefer to do a split application of 70 lbs UAN 32/acre in the spring + 55 lbs UAN 28/acre with a sidedress application, the calculation would be:

Lbs UAN 32: 70 lbs/3.5 lbs N per gallon = 20 gallons per acre UAN 32 applied in spring

Lbs UAN 28: 55 lbs/2.9 lbs N per gallon = ~19 gallons per acre UAN 28 applied as a sidedress

Get more in-depth recommendations for determining nitrogen rates for corn here.

Nitrogen Management Best Practices

Managing nitrogen effectively not only reduces your production costs, it also ensures your crops have the nitrogen they need during critical uptake periods to maximize yield potential. Nitrogen management is also essential to reduce the environmental impacts of fertilizer applications, which may be prone to leaching, volatilization, and off-target movement due to erosion. Your nitrogen application strategy should include considerations of rate, timing, source, and placement.

6 Ways to Manage Nitrogen More Effectively

1. Use soil testing: Soil tests can help you determine a baseline nitrogen level in your soil, so you can adjust fertility rates depending on your crop’s expected yield potential. Learn how to read a soil analysis test here.

2. Spoon-feed crops: If possible, consider splitting nitrogen applications. Applying nitrogen as close to a crop’s critical uptake period as possible helps reduce the risk of environmental losses and ensures nutrients are available when crops need them.

3. Leverage technology: Variable rate fertilizer applications allow you to adjust fertilizer rates throughout the field to apply only what’s necessary, reducing input costs and the risk of overfertilization. 

4. Protect nitrogen applications: Nitrogen stabilizers are an excellent way to reduce the risk of nitrogen losses due to leaching and volatilization. These products help keep more nitrogen in the root zone by reducing losses due to volatilization and leaching. There are nitrogen stabilizers available for use with nearly every nitrogen source and application timing. FBN nitrogen stabilizer is a great option for minimizing volatilization with urea and UAN applications. 

5. Reduce erosion risks: Reduced tillage and cover crops can keep soils covered to reduce erosion risks and also help to build soil health to improve nutrient cycling. (Learn how you can get rewarded for regenerative ag practices here.)

6. Manage irrigation: When using irrigation, develop a watering schedule that increases efficiency and uniformity to avoid excess drainage and nitrogen leaching risks.  

Wondering which nitrogen stabilizer is a good fit for your application? Find out here.

Buy Nitrogen from FBN

FBN offers a complete crop nutrition portfolio, including high-uptake nutrients like Farmers First™ Inhabit N™, a highly available nitrogen source that can be applied in-furrow at planting, sidedress, or via soil/foliar broadcast to support a growing crop’s nitrogen demands; bulk liquid fertilizer products; carbon sources; and soil prebiotics and probiotics to supplement your crop nutrition program. Spoon-feeding your crop through foliar applications during the season with products like Atarrus^TM or Nourish Vitals^TM can also deliver N and other micronutrients your crop may need.

With a user-friendly online platform, transparent pricing, and direct-to-farm delivery available on your schedule, FBN puts Farmers First^®. 

Related Resources

• How Can the Maximum Return to Nitrogen Calculator Increase Your Profit Potential?

• See Nitrogen Efficiency of Top Varieties

• Crop Nutrition 101: Everything Growers Need to Know About Crop Nutrition

• Herbicides 101: Everything Growers Need to Know About Herbicides

• Adjuvants 101: Understanding the “Extras” In Your Tank

• Surfactants 101: Understanding the “Extras” In Your Tank

• Fungicides 101: Everything Farmers Need to Know About Fungicides

• Insecticides 101: Everything Farmers Need to Know About Insecticides

• Inoculants 101: Everything Farmers Need to Know About Inoculants

• Biostimulants 101: Everything Growers Need to Know About Biostimulants

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