Ammonium Sulphate Fertiliser – Sulphate Of Ammonia Uses, Benefits and Application


Ammonium sulphate is one of the most widely used inorganic fertilizers. This article provides a detailed overview of ammonium sulphate, its role as a nitrogen and sulphur fertilizer, and best practices for application in agriculture and horticulture.

As a premium soluble nitrogen and sulphur fertilizer, ammonium sulphate offers significant benefits which make it a popular choice for farmers and growers. Read on to learn more about maximizing the performance of this versatile compound.

What is Ammonium Sulphate?

Ammonium sulphate is an inorganic salt made up of 21% nitrogen and 24% sulphur by weight. Its chemical name is ammonium sulfate [(NH4)2SO4] and it possesses a highly soluble, crystalline form.

The manufacturing process involves reacting ammonia gas with sulphuric acid to produce a precipitated white powder. Granulating or crystallizing the powder results in the final pelletized product.

Key properties that underpin the usefulness of ammonium sulphate fertilizer include:

  • An immediately available source of nitrogen and sulphur for rapid plant uptake
  • 100% water soluble and non-volatile ammonium nitrogen form
  • Soil acidifying effect from the sulphur content
  • Compatibility with most pesticides and liquid fertilizer blends
  • Low risk of leaching or runoff compared to other nitrogen sources
  • Cost effectiveness as a straight nitrogen fertilizer

With these beneficial characteristics, ammonium sulphate is widely applied in broadacre cropping, pastures, horticulture, turf and other farming systems.

Why is it an Effective Fertilizer?

The sulphate form of ammonium nitrogen offers important advantages that enhance ammonium sulphate’s efficacy as a fertilizer.

Firstly, since the nitrogen is present as ammonium rather than nitrate, it is not prone to leaching or loss through denitrification. Secondly, the sulphur content boosts overall nutrient availability for plants.

Some key benefits include:

  • Readily available nitrogen – Present in the ammonium form which is instantly usable by plants upon application.
  • Non-volatile – Ammonium nitrogen does not volatilize or convert to gaseous compounds when broadcast, unlike urea.
  • Acidifying effect – The sulphur content reacts in soil to lower pH over time. This aids availability of certain nutrients.
  • Sulphur supply – An economical sulphur source, important for plant growth and as a soil conditioner.
  • Chloride-free – Unlike some nitrogen fertilizers, contains no chloride which can adversely accumulate in soils.
  • Compatible – Can be blended with other liquid or granular NPK fertilizers or applied concurrently with pesticides.

With a nitrogen to sulphur ratio of 2:1, ammonium sulphate is an efficient choice for delivering both of these key macronutrients.

How is Ammonium Sulphate Applied?


Ammonium sulphate fertilizer is suitable for solid broadcast application or liquid application via fertigation systems. Granular ammonium sulphate contains a minimum of 99% dry matter and spreads evenly.

  • Broadcast application – Evenly apply granular ammonium sulphate fertilizer to the soil surface pre-planting or as a top dressing. Lightly water in to move nutrients into the root zone.
  • Fertigation – Soluble ammonium sulphate is ideal for application through irrigation systems. Delivers a consistent nutrient supply directly to the root zone.
  • Foliar sprays – Dilute rates can be foliar applied but are generally less efficient than soil application. Foliar uptake risks leaf burn without adequate dilution.

Ammonium sulphate is highly water soluble so does not require extended watering in to take effect. It can be blended with other fertilizers to create custom NPK blends.

Ammonium Sulphate Use Rates

Recommended application rates for ammonium sulphate depend on factors like soil conditions, crop type, growth stage and yield targets. Some typical use rates include:

  • Cereal crops – 50-150 kg/ha
  • Pasture – 50-100 kg/ha
  • Cotton – 150-250 kg/ha
  • Sugarcane – 100-250 kg/ha
  • Turf – 25-75 g/m2
  • Vegetables – 250-500 kg/ha
  • Tree crops/vines – 250-600 kg/ha

Always follow manufacturer guidelines on maximum application rates. Excess nitrogen can cause issues like lodging and burning. Split applications spaced through the season are generally more efficient than a single large application.

Which Crops Respond Well to Ammonium Sulphate?

The rapid nitrogen supply suits high nitrogen-demanding crops while the sulphur boosts growth and quality. Crops that commonly receive ammonium sulphate fertilizer include:

  • Cereals – Wheat, barley, oats, sorghum
  • Cotton
  • Sugarcane
  • Corn
  • Pasture grasses
  • Brassicas – Canola, cabbage, broccoli
  • Alliums – Onions, leeks, garlic
  • Legumes – Soybeans, peas, lentils
  • Root vegetables – Carrots, potatoes, sweet potato
  • Tree fruits and vines
  • Ornamentals and turf

Leafy crops often show strong yield and quality responses from the combined nitrogen and sulphur nutrition provided by ammonium sulphate.

When Should You Apply Ammonium Sulphate?

Timing of fertilizer applications is an important factor in getting the most value from ammonium sulphate.

  • Pre-plant – Apply and incorporate before planting to support early root and crop establishment.
  • Post-emergent – Top dress after emergence, Before stem elongation provides nitrogen for rapid growth.
  • Fertigation – Frequent low dose applications through irrigation during rapid bulking delivers a steady nutrient supply.
  • Post-harvest – Autumn application emphasizes nitrogen storage in vegetative parts for yield next season.
  • Avoid hot conditions – Evaporation can lead to fertilizer burning leaves or roots in extreme heat.

Paying close attention to crop demand and seasonal conditions will optimize fertilizer efficiency.

Are There any Risks or Downsides to Ammonium Sulphate Use?

When used correctly ammonium sulphate is a safe and reliable fertilizer. However, some potential issues to be aware of include:

  • Overuse can push soil acidity too low over time
  • Nitrogen loss through leaching if excessively applied
  • Potential root or leaf burn if applied at very high rates
  • Contains no nutrients besides nitrogen and sulphur
  • Less concentrated than some nitrogen fertilizers

Following manufacturer guidelines on rates, paying attention to soil pH changes and alternating with other nutrient sources helps avoid most risks.


Q: What is ammonium sulphate fertilizer?

A: Ammonium sulphate fertilizer, also known as sulphate of ammonia, is a nitrogen fertilizer containing 21% nitrogen and 24% sulphur in the form of sulphate. It is commonly used for its high nitrogen content.

Q: What are the uses of ammonium sulphate fertilizer?

A: Ammonium sulphate fertilizer is primarily used as a nitrogen source for agricultural crops. It is also used in the manufacturing of other fertilizers, fire retardants, herbicides, and in certain industrial processes.

Q: What are the benefits of using ammonium sulphate fertilizer?

A: Ammonium sulphate fertilizer offers several benefits, such as providing readily available nitrogen to plants, promoting strong leaf growth in all plants, improving the greening effect, especially in leaf crop vegetables, and enhancing the uptake of magnesium in plants. It also contributes to better moisture retention in the soil.

Q: How is ammonium sulphate fertilizer applied to the soil?

A: Ammonium sulphate fertilizer can be applied to the soil using various methods, including broadcasting, side dressing, and incorporation into the soil before planting. The application method depends on the specific situation and the type of crop being grown.

Q: Can ammonium sulphate fertilizer be used on all types of soil?

A: Ammonium sulphate fertilizer can be used on a wide range of soil types, including sandy, clay, and loamy soils. However, it is important to note that the application rates may vary depending on the soil type and nutrient requirements of the crops.

Q: What is the recommended application rate for ammonium sulphate fertilizer?

A: The recommended application rate of ammonium sulphate fertilizer varies depending on factors such as crop type, soil fertility, and desired nutrient levels. It is best to consult a local agricultural expert or soil testing laboratory to determine the optimal application rate for your specific situation.

Q: Is it necessary to water in ammonium sulphate fertilizer after application?

A: Yes, it is recommended to water in ammonium sulphate fertilizer after application. Watering helps to dissolve the granules and allows the nutrients to be readily available for plant uptake. Watering also helps to prevent potential volatilization of the nitrogen content.

Q: Can ammonium sulphate fertilizer be used in conjunction with other fertilizers?

A: Yes, ammonium sulphate fertilizer can be used in conjunction with other fertilizers to meet the specific nutrient requirements of the crops. It is often blended with other nitrogen fertilizers, such as urea or ammonium nitrate, to provide a balanced nutrient supply.

Q: How often should ammonium sulphate fertilizer be applied?

A: The frequency of ammonium sulphate fertilizer application depends on the specific crop, soil conditions, and nutrient requirements. As a general guideline, it is recommended to apply ammonium sulphate fertilizer 2 to 4 times per year, with each application spaced evenly throughout the growing season.

Q: Are there any precautions to be taken when using ammonium sulphate fertilizer?

A: Yes, there are a few precautions to be taken when using ammonium sulphate fertilizer. It is important to avoid applying the fertilizer in extreme weather conditions, such as during very hot or very wet periods, to prevent the loss of nutrients through volatilization or leaching. It is also recommended to store the fertilizer in a cool, dry place away from direct sunlight.

Key Takeaways on Ammonium Sulphate Fertilizer

  • Provides an immediately plant-available nitrogen and sulphur source
  • Rapid uptake promotes leafy growth and plant quality
  • Ammonium nitrogen form resists leaching and volatilization losses
  • Useful asset for fertigation systems due to high solubility
  • Works well blended with other NPK fertilizers
  • Leafy crops, cereals and high N-demand plants respond best
  • Apply before planting, during early growth or through peak demand
  • Moderate rates split through the season provide optimal efficiency

With both nitrogen and sulphur deficiency increasingly common in soils worldwide, ammonium sulphate is a valuable fertilizer option. Follow best practice guidelines to harness the benefits it provides for agricultural and horticultural productivity.

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