Comparing Ammonium Sulfate and Ammonium Nitrate Fertilizer (Application &Timing)

Choosing between ammonium sulfate and ammonium nitrate depends on more than nitrogen content. Both are nitrogen fertilizers, but they differ in nutrient concentration, nitrogen forms, sulfur supply, and effects on soil acidity. Understanding these differences helps farmers select a fertilizer that matches their crops’ needs and soil conditions. Ammonium sulfate typically contains 21% nitrogen and 24% sulfur, while ammonium nitrate commonly contains 33–34% nitrogen and no sulfur. This makes ammonium sulfate useful when crops need both nitrogen and sulfur, whereas ammonium nitrate provides a more concentrated source of nitrogen.

However, neither fertilizer is automatically the better choice for every crop or field. Soil pH, nutrient requirements, application timing, local availability, handling requirements, and fertilizer costs all influence the decision. This guide compares ammonium sulfate vs ammonium nitrate and explains when each fertilizer may be more suitable for agricultural use.

Ammonium Sulfate vs Ammonium Nitrate at a Glance

The table below summarizes the main differences between these two fertilizers.

Feature	Ammonium Sulfate	Ammonium Nitrate
Nitrogen content	Typically 21%	Commonly 33–34%
Sulfur content	Typically 24%	None
Nitrogen forms	Ammonium nitrogen	Ammonium and nitrate nitrogen
Main purpose	Supplies nitrogen and sulfur	Supplies concentrated nitrogen
Immediate nitrate nitrogen	None in the standard product	Approximately half of its nitrogen
Soil acidification	Generally strongly acidifying	Also acidifying over time
Main advantage	Supplies two essential nutrients	Supplies more nitrogen per unit of product
Main consideration	Sulfur demand and soil pH	Availability, handling, regulations, and nitrogen management

Actual nutrient content can vary by product, so always check the guaranteed analysis on the label or technical data sheet. The most important difference between ammonium sulfate and ammonium nitrate is their nutrient profile. Ammonium sulfate supplies nitrogen and sulfur, while ammonium nitrate supplies more nitrogen per ton and provides nitrogen in two forms: ammonium and nitrate.

Nitrogen Content: Which Fertilizer Supplies More Nitrogen?

Nitrogen content is one of the most practical differences in this fertilizer comparison. Ammonium sulfate typically contains 21% nitrogen. This means one metric ton supplies approximately 210 kg of nitrogen and 240 kg of sulfur when the product contains 24% sulfur.

Ammonium nitrate commonly contains 34% nitrogen. One metric ton of this product supplies approximately 340 kg of nitrogen. As a result, ammonium nitrate supplies substantially more nitrogen per ton than ammonium sulfate. For example, to supply 100 kg of nitrogen, the theoretical product requirements would be:

• Ammonium sulfate at 21% N: Approximately 476 kg of fertilizer.
• Ammonium nitrate at 34% N: Approximately 294 kg of fertilizer.

These figures are nutrient calculations, not application recommendations. The actual rate should follow the crop’s nitrogen requirement, soil-test results, and local agronomic guidance. The difference in nitrogen concentration also affects transportation, storage, and field application. Where logistics costs are high, a more concentrated fertilizer may reduce the amount of product that must be transported and handled to supply the same quantity of nitrogen. However, a lower application volume does not automatically mean a lower total fertilizer cost. Prices, sulfur requirements, transport costs, and application expenses must all be considered.

Nitrogen Forms and Availability

Another important difference between ammonium sulfate and ammonium nitrate is the form in which they supply nitrogen. Plants can take up nitrogen mainly as ammonium (NH₄⁺) and nitrate (NO₃⁻). Both forms support plant growth, but they behave differently in soil.

Ammonium nitrate: Ammonium and nitrate nitrogen

Ammonium nitrate supplies nitrogen in both forms. A typical product contains approximately equal amounts of ammonium nitrogen and nitrate nitrogen, although the exact analysis should be checked. The nitrate portion is already in a form that roots can absorb without waiting for nitrification. The ammonium portion becomes available for uptake and can also undergo nitrification. This combination makes ammonium nitrate a useful option when a fertilizer program requires both immediately available nitrate nitrogen and ammonium nitrogen. However, having nitrate nitrogen does not guarantee better crop performance in every situation. Nitrate can move readily with soil water, so rainfall, irrigation, soil texture, and application timing remain important. The practical distinction is that ammonium sulfate relies on ammonium nitrogen, while ammonium nitrate supplies both ammonium and nitrate directly.

Note: Ammonium nitrate is suitable for plants growing in alkaline soils.

Ammonium sulfate: Ammonium nitrogen

Ammonium sulfate supplies its nitrogen in the ammonium form. After the fertilizer dissolves in soil moisture, ammonium becomes available for plant uptake. Soil microorganisms can also convert ammonium into nitrate through a process called nitrification. The speed of this process depends on factors such as soil temperature, moisture, aeration, and microbial activity. Ammonium is positively charged and can be held on negatively charged soil particles. This can reduce its immediate movement through soil compared with nitrate, although the extent depends on soil properties. Once ammonium is converted into nitrate, it becomes more mobile and may be lost through leaching if rainfall or irrigation moves it below the root zone.

Note: Ammonium sulfate has an acidic pH and is more suitable for plants growing in acidic soils.

Sulfur Content: The Main Advantage of Ammonium Sulfate

Sulfur is the clearest reason to choose ammonium sulfate over ammonium nitrate when both fertilizers are being considered as nitrogen sources. Ammonium sulfate typically supplies 24% sulfur in addition to 21% nitrogen. Sulfur is essential for amino acid and protein formation, enzyme activity, and normal plant development. Crops that require substantial sulfur may benefit from a fertilizer that supplies nitrogen and sulfur together. This can simplify nutrient management when both elements are needed.

When is ammonium sulfate the better option?

Ammonium sulfate may be preferable when:

• Soil testing or crop recommendations indicate a sulfur deficiency or a need for additional sulfur.
• The crop requires nitrogen and sulfur during the same growth period.
• A single fertilizer source can meet part of both nutrient requirements.
• The fertilizer program needs to correct nitrogen and sulfur shortages without adding unnecessary phosphorus or potassium.

For example, sulfur demand can be important in crops such as canola, other oilseed crops, and some legumes. Actual requirements vary with crop species, yield goals, soil conditions, and the amount of sulfur already available.

What if the soil already has enough sulfur?

If sulfur is sufficient, ammonium nitrate may be a practical alternative nitrogen source, provided it is legally available and suitable for the farm’s operation. Using ammonium sulfate when no additional sulfur is needed may still be agronomically possible, but its sulfur contribution should be included in the nutrient budget. The fertilizer should be selected based on the total cost and value of its nutrients, not nitrogen price alone. To understand sulfur-related crop symptoms, see our guide to the signs of nutrient deficiency in plants.

Soil pH and Acidification

Soil pH is another important factor when comparing ammonium sulfate vs ammonium nitrate. Both fertilizers can contribute to soil acidification, so it is inaccurate to describe ammonium sulfate as acidic and ammonium nitrate as neutral. The main process involves the conversion of ammonium nitrogen into nitrate through nitrification. This process releases hydrogen ions, which can lower soil pH over time.

Ammonium sulfate is generally considered a strongly acidifying nitrogen fertilizer. Ammonium nitrate can also acidify soil because its ammonium component undergoes nitrification. The long-term effect depends on the nitrogen rate, crop uptake, nitrate leaching, soil buffering capacity, and the wider nutrient management program.

What does this mean for acidic soils?

If the soil is already acidic, repeated applications of either fertilizer should be managed carefully. Applying more nitrogen than the crop needs can increase nutrient losses and contribute to further soil acidification. Before choosing a nitrogen source, consider:

• Current soil pH and the soil’s buffering capacity.
• Crop tolerance to acidic conditions.
• The planned nitrogen rate and application frequency.
• Whether lime or another suitable amendment is needed.
• The potential for nitrate leaching under local rainfall and irrigation conditions.

Ammonium sulfate can still be appropriate in an acidic soil when sulfur is required, but the nutrient benefit must be weighed against the need to manage soil acidity. Learn more about managing acidic soil before making repeated fertilizer applications to fields with low pH.

Which Fertilizer Is Better for Sulfur-Deficient Soil?

When a crop needs both nitrogen and sulfur, ammonium sulfate is generally the more direct choice of these two fertilizers. Its typical 21% nitrogen and 24% sulfur content allows farmers to supply both nutrients through one product. This may be particularly useful when soil tests show that sulfur availability is low and the crop also requires nitrogen.

Ammonium nitrate cannot correct sulfur deficiency because it does not contain sulfur. If ammonium nitrate is selected to meet the nitrogen requirement, sulfur must be supplied through another suitable source when the crop needs it. However, not every plant showing yellow leaves has a sulfur deficiency. Nitrogen deficiency, root problems, poor drainage, unsuitable soil pH, and other nutrient disorders can produce similar symptoms.

Use soil or plant testing, where appropriate, to identify the cause before changing the fertilizer program. Also consider the sulfur already supplied by manure, irrigation water, previous fertilizer applications, and other amendments. The aim is to meet the crop’s total sulfur requirement, not to apply the maximum possible amount.

Which Fertilizer Is Better When Only Nitrogen Is Needed?

When the crop requires nitrogen but does not need additional sulfur, ammonium nitrate may be a suitable option if it is available and permitted for the intended use. Its higher nitrogen concentration means less product is required to supply the same amount of nitrogen compared with standard ammonium sulfate. Its nitrate component is also immediately available for plant uptake, while the ammonium component can be absorbed or converted through nitrification.

Nevertheless, ammonium nitrate is not the only option for nitrogen-only fertilization. Urea and other nitrogen fertilizers may also suit the crop, soil, climate, and application method. The choice should consider the complete nutrient plan rather than nitrogen concentration alone. A fertilizer with more nitrogen per ton may not be the most economical choice if its price is higher or if transport, storage, and handling requirements increase costs.

Ammonium nitrate also faces additional transport, storage, and regulatory requirements in many jurisdictions because of its oxidizing properties and potential security risks. Availability and permitted uses vary by country. Agricultural buyers should confirm applicable rules and supplier requirements before selecting it. For this reason, the practical answer to whether you should choose ammonium sulfate or ammonium nitrate depends on both agronomic needs and local operating conditions.

Ammonium Sulfate vs Ammonium Nitrate: Which Should You Choose?

The right fertilizer depends on the nutrients your crop needs and the conditions in which you will apply it.

Choose ammonium sulfate when:

• The crop requires both nitrogen and sulfur.
• Soil testing or crop recommendations indicate a need for additional sulfur.
• You want to supply nitrogen and sulfur through one fertilizer product.
• Its nutrient value, price, and handling characteristics suit your operation.
• Soil pH is monitored and the fertilizer’s acidifying effect can be managed appropriately.

Consider ammonium nitrate when:

• The main requirement is nitrogen rather than sulfur.
• Both ammonium and nitrate nitrogen are suitable for the crop and application schedule.
• A higher nitrogen concentration offers a practical advantage in transport or application.
• The product is legally available and appropriate for your operation.
• Its total cost and handling requirements compare favorably with other nitrogen sources.

Before deciding, calculate the required nitrogen rate and account for all other nutrient sources. If sulfur is required, include its cost and value in the comparison. If soil acidity is a concern, consider the long-term effect of the entire nitrogen program rather than judging a fertilizer by its name alone.

For buyers comparing standard crystalline products, check the specifications for the 21-24 ammonium sulfate grade and review the guaranteed nutrient analysis before purchase. BARNO’s crystalline ammonium sulfate fertilizer may be suitable for agricultural programs that require a nitrogen and sulfur source, depending on the crop and soil requirements.

How to Use Ammonium Sulfate and Ammonium Nitrate

The best time to apply ammonium nitrate fertilizer is during the early stages of plant growth. In these initial phases, plants require more nitrogen. Receiving additional nitrogen accelerates plant growth. For some crops, applying ammonium nitrate in later growth stages is also necessary. For fruit-bearing trees, using ammonium nitrate fertilizer during flowering and fruit formation stages can help increase yields. The type of crop, weather conditions, and soil conditions are factors that influence the timing of ammonium nitrate application. For crops with short growth periods, ammonium nitrate is typically applied in the early growth stages. In hot and dry climates, it’s better to apply ammonium nitrate early to prevent nitrogen evaporation. The amount of ammonium nitrate used also depends on the crop type, weather, and soil conditions.

The method of applying ammonium sulfate fertilizer is determined based on the plant’s and soil’s needs. However, there is generally a global standard for using ammonium sulfate. Ammonium sulfate is applied in three periods, usually in the months of April, June, and September. As a final note, we emphasize that determining a plant’s needs, along with the amount and timing of fertilization, is a highly specialized matter. For fertilizing farmland or orchards, it’s best to seek the expert opinion of an agricultural specialist.

Conclusion

The main difference between ammonium sulfate and ammonium nitrate is their nutrient composition and nitrogen forms. Ammonium sulfate typically supplies 21% ammonium nitrogen and 24% sulfur, while ammonium nitrate commonly supplies 33–34% nitrogen split between ammonium and nitrate forms. Ammonium sulfate is particularly useful when a crop needs both nitrogen and sulfur. Ammonium nitrate provides more nitrogen per ton and supplies nitrate nitrogen directly, but it does not meet sulfur requirements.

Both fertilizers can contribute to soil acidification, and both must be applied according to crop needs and appropriate nutrient recommendations. The best choice is the one that meets the required nutrient balance, suits local soil conditions, and makes economic sense for the operation. A soil test, a clear nutrient budget, and a review of local product availability provide a stronger basis for choosing a fertilizer than nitrogen concentration alone.