Application of Ammonium Sulfate in Agriculture: A Comprehensive Guide for Professional Farmers
Why Ammonium Sulfate is a Strategic Fertilizer in Agriculture
Modern agriculture is no longer limited to traditional farming methods. Today, farmers’ goals are not only crop yield but also quality, high performance, economic profit, and soil sustainability. To achieve these objectives, selecting the right fertilizer becomes crucial.
Among nitrogen fertilizers, ammonium sulfate holds a unique position. This chemical not only provides the nitrogen plants need but also serves as a valuable source of sulfur—a nutrient that is deficient in many soils in Iran. For this reason, farmers worldwide, from wheat and rice fields to orchards and vegetable farms, use this fertilizer to enhance productivity.
According to the FAO, over 25% of the world’s agricultural soils are sulfur-deficient. In Iran, due to alkaline and calcareous soils, this deficiency is more severe. Therefore, using ammonium sulfate is not merely a choice but a necessity.
Using ammonium sulfate increases crop yield while improving the quality of grains, fruits, and vegetables. For example:
In wheat, it increases protein content and improves bread quality.
In rice, it enhances the aroma and taste of grains.
In onions, it increases sulfur compounds, giving them a stronger flavor.
Thus, ammonium sulfate is not just a simple fertilizer but a strategic tool in farm management.
Chemical Composition and Key Features of Ammonium Sulfate
Ammonium sulfate, with the chemical formula (NH₄)₂SO₄, is one of the most stable and widely used nitrogen fertilizers. Its composition provides two essential elements for plant growth simultaneously:
| Element | Content | Role |
|---|---|---|
| Nitrogen | 21% | Main driver of plant growth. Vital for chlorophyll, proteins, and enzymes. Unlike nitrate nitrogen, ammonium nitrogen (NH₄⁺) is more stable in Iran’s calcareous soils and is gradually available to plants. |
| Sulfur | 24% | Essential for amino acids and certain enzymes. Important for sulfur-loving crops like onion, canola, and garlic. Sulfate (SO₄²⁻) is highly water-soluble and immediately available to roots. |
Important Features of Ammonium Sulfate
High solubility in water: Makes it ideal for drip and sprinkler irrigation systems.
Gradual reduction of soil pH: Improves uptake of micronutrients like iron, zinc, and manganese in alkaline soils.
Greater stability than urea: Unlike urea, which volatilizes quickly in hot and dry conditions, ammonium sulfate remains stable.
Safety: Unlike ammonium nitrate, it has lower explosion risks and fewer regulatory restrictions.
Practical Example: Wheat Field Study
In a field experiment in Khorasan Razavi Province, wheat fields treated with ammonium sulfate showed:
15% increase in yield
Better bread quality (due to higher sulfur and protein content)
This demonstrates how the combination of nitrogen and sulfur can make a significant difference.
1. Ammonium Sulfate Applications in Cereals: From Wheat to Rice and Corn
Wheat: The Backbone of Iranian Agriculture
Wheat is Iran’s most important crop, and food security relies on it. Growth and yield are heavily influenced by nitrogen and sulfur levels.
Benefits of using ammonium sulfate in wheat fields:
Increased grain protein: Improves bread quality. Studies at the University of Tehran showed a 2% increase in protein content.
Improved bread quality: Sulfur enhances gluten content and dough texture, resulting in better bread.
Better yield: Ammonium nitrogen promotes uniform growth and increases tillers.
Farmers in regions like Isfahan and Khorasan report that ammonium sulfate also prevents leaf yellowing caused by sulfur deficiency, unlike urea.
Rice: Improving Grain Aroma and Quality
Rice is one of Iran’s staple crops. The quality of Iranian rice (e.g., Tarom, Hashemi) depends on aroma and yield.
Benefits of ammonium sulfate in rice:
Increased panicle number: Nitrogen promotes tillering and panicle formation.
Enhanced grain aroma: Sulfur increases aromatic compounds. Research by the Rasht Rice Research Institute confirmed better aroma in ammonium sulfate-treated rice versus urea-treated rice.
Reduced lodging: Sulfur and nitrogen strengthen cell walls, making stems more resistant.
Corn: A Strategic Crop for Food and Feed
Corn is used both for human consumption and livestock feed. Adequate nitrogen is essential for high-yield corn production.
Benefits of ammonium sulfate in corn:
Increased chlorophyll and leaf growth: Promotes faster vegetative growth.
Improved grain quality for feed: Sulfur helps synthesize essential amino acids like methionine and cysteine.
Prevents sulfur deficiency: Common in Iran’s alkaline soils, symptoms include yellowing of young leaves.
Studies by the Ministry of Agriculture show ammonium sulfate increases corn yield by 10–15%.
2. Applications in Fruit Orchards
Citrus: Oranges, Lemons, Mandarins
Iran is a major citrus producer, especially in Mazandaran, Fars, and Hormozgan. Citrus requires nitrogen and sulfur for growth, yield, and fruit quality.
Benefits:
Improved fruit color and flavor
Thicker fruit peel for reduced drop and longer shelf-life
Prevention of leaf yellowing due to sulfur deficiency
Research: Citrus orchards using ammonium sulfate showed 15% higher yield and 10% better juice quality.
Grapes
Benefits:
Increased sweetness and Brix percentage
Enhanced color of grapes
Longer post-harvest shelf-life
Apples
Benefits:
Larger fruit size
Better skin color and brightness
Improved storage life
Other Fruits: Peach, Pomegranate, Pistachio
Peach and apricot: Higher sugar content and better color
Pomegranate: Uniform seeds and improved red color
Pistachio: Increased yield and reduced kernel hollowing
3. Applications in Vegetables and Herbs
Tomatoes
Better red color: Sulfur enhances lycopene synthesis
Improved taste and acidity: Nitrogen boosts sugars and organic acids
Increased disease resistance: Sulfur has antifungal properties
Studies at Shiraz University reported 8% yield increase and 12% improved fruit color with ammonium sulfate versus urea.
Cucumbers
Uniform growth and greener fruits
Improved skin quality and transportability
Potatoes
Higher tuber yield
Better frying quality due to reduced reducing sugars
Prevention of sulfur deficiency
Studies in Hamedan Province: 20% yield increase and better cold storage life.
Onions
Increased sulfur compounds for stronger flavor and antimicrobial properties
Improved skin quality and storage
Better exportability
Leafy Vegetables: Lettuce, Spinach, Fresh Herbs
Greener leaves due to higher chlorophyll
Improved taste and nutritional value
Faster growth and earlier harvest
Recommended Application Rates (Summary Table)
| Crop | Recommended Dose | Practical Effects |
|---|---|---|
| Wheat | 150–200 kg/ha | Increased yield, improved gluten quality |
| Rice | 100–150 kg/ha | Increased panicle formation, better cooking quality |
| Fruit Orchards | 2–3 kg/tree | Better color and flavor |
| Vegetables | 50–70 kg/ha | Increased growth and shelf-life |
| Corn | 120–180 kg/ha | Increased kernels per cob |
| Sugarcane | 200–300 kg/ha | Increased stalk growth and sugar content |
| Potatoes | 100–150 kg/ha | Higher starch content, improved cooking quality |
Advantages and Disadvantages of Ammonium Sulfate
Advantages
Provides nitrogen and sulfur simultaneously
Corrects alkaline soils and improves nutrient uptake
Improves crop quality (color, taste, shelf-life)
Reduces fungal diseases by strengthening plant tissue
Disadvantages
Can lower pH excessively in acidic soils
Lower nitrogen content than urea (21% vs 46%)
Higher transportation cost due to weight
Comparison with Other Fertilizers
| Fertilizer | Comparison |
|---|---|
| Urea | Higher nitrogen but lacks sulfur; less effective on alkaline soils |
| Ammonium Nitrate | Quick absorption but higher explosion risk; ammonium sulfate safer |
| Potassium Sulfate | Provides K and S, but not N; ammonium sulfate necessary for N requirement |
Application Methods
Basal application (pre-planting): Mix with soil for gradual nutrient availability.
Top-dressing: Applied during vegetative growth to boost yield.
Foliar spray: Especially for orchards or crops needing sulfur.
Furrow placement (for trees): Fertilizer placed near roots for direct uptake.
Environmental Effects
Reduced groundwater contamination: Gradual nitrogen release lowers nitrate leaching.
Compatible with sustainable agriculture: Supports better soil and water resource management.
Pricing and Purchasing Guide
Factors Affecting Price
Purity (99% ideal for sensitive crops)
Country of origin (Iran, China, India, Turkey)
Packaging (25 kg bags, 1000 kg bulk)
Currency fluctuations and transport costs
Purchasing Recommendations
Buy from suppliers providing Certificate of Analysis (COA)
Ensure quick solubility and absence of impurities
Choose a reputable ammonium sulfate brand
Why choose a professional-grade ammonium sulfate brand?
Ammonium sulfate is a strategic fertilizer in Iran:
Supplies N and S simultaneously
Reduces pH in alkaline soils
Boosts crop yield and quality
A reputable brand ensures high purity, standardized packaging, and competitive pricing, helping farmers increase profitability and crop quality. Contact expert consultants for guidance.
References:
FAO – Fertilizer Use by Crop
IFA – Ammonium Sulfate Overview