Introduction

Sulphur is a key macronutrient in modern fertilizers and plays a major role in improving crop yield and quality. Many farming regions face sulphur-deficient soils due to intensive cultivation and lower atmospheric deposition. As a result, sulphur fertilizers are now essential for balanced plant nutrition, especially in cereal, oilseed, and vegetable production.

In the fertilizer industry, sulphur is mainly used in elemental form and as sulphates. These forms support soil pH management, improve nutrient uptake, and work closely with nitrogen and phosphorus. Today, global sulphur use still meets only about half of total crop demand, making sulphur fertilization an important focus for growers and fertilizer producers.

Core Chemical Functions of Sulphur

Sulphur supports plant growth in several direct and indirect ways. In soil, elemental sulphur is converted by natural bacteria into sulphuric acid. This process lowers soil pH, which is especially useful in alkaline soils. As pH drops, key nutrients such as phosphorus, nitrogen, iron, and zinc become easier for plants to absorb.

Plants take up sulphur mainly as sulphate. This form is vital for protein formation, enzyme activity, and chlorophyll production. Without enough sulphur, crops show poor growth, pale leaves, and reduced yield quality.

Elemental sulphur releases nutrients more slowly than sulphate fertilizers. This slow release reduces nutrient loss from leaching, especially in sandy or high-rainfall areas. Granular sulphur products blended with bentonite absorb water and break apart in the soil, helping sulphur spread evenly and oxidize at a steady rate over time.

Industrial Production and Fertilizer Manufacturing

Sulphur is added to fertilizers at different production stages, depending on the product type. In nitrogen fertilizers, sulphur is often combined with urea to form urea plus elemental sulphur (U+ES). Very fine sulphur particles are mixed into molten urea with stabilizing agents, then shaped into granules or prills. These products supply both fast nitrogen and slow-release sulphur.

Urea ammonium sulphate (UAS) is produced by adding sulphuric acid to urea solutions. This process is efficient and uses reaction heat to reduce energy use. UAS products are widely used in large-scale farming due to their balanced nitrogen and sulphur content.

Sulphur bentonite fertilizers are made by forming molten sulphur into small pastilles with clay. Once applied to soil, they swell and break apart, releasing sulphur gradually. In phosphate fertilizers, sulphuric acid is essential for converting phosphate rock into plant-available forms such as superphosphate.

Modern fertilizer plants use advanced granulation and blending systems to manage sulphur levels while avoiding handling and storage issues.

Use Across Fertilizer Sectors

Elemental sulphur is widely used for long-term soil improvement, especially in regions with strong sulphur shortages such as parts of India and Africa. It is best suited for base applications before planting, where slow nutrient release is an advantage.

Sulphate fertilizers like ammonium sulphate are preferred when crops need fast sulphur uptake. These are often applied during planting or early growth stages but may require careful management in wet climates due to leaching risk.

In nitrogen-intensive crops such as cereals and oilseeds, sulphur improves nitrogen efficiency and protein formation. Orchards, vineyards, and saline soils benefit from sulphur bentonite due to its long-lasting effect and soil-conditioning properties. Liquid sulphur products are mainly used in specialized foliar or fertigation systems.

The choice of sulphur form depends on crop type, soil condition, climate, and timing of application.

Operational Value and Efficiency

Sulphur improves nitrogen use efficiency by helping plants convert nitrogen into usable proteins. On average, each kilogram of sulphur allows crops to use 5 to 10 kilograms more nitrogen. This reduces fertilizer waste and lowers overall input costs.

Yield improvements of around 10 percent are common in sulphur-deficient soils. Slow-release sulphur products reduce nutrient loss and improve return on investment, especially in bulk fertilizer programs. Acidification from sulphur also improves soil structure, airflow, and microbial activity, supporting long-term soil health.

Transport and storage costs are also optimized with high-analysis sulphur fertilizers, which deliver more nutrients per tonne. Growing demand from large fertilizer markets such as India and Brazil continues to support sulphur use despite price fluctuations linked to fertilizer and energy markets.

Conclusion

Sulphur plays a vital role in the fertilizer industry by improving nutrient balance, soil health, and crop performance. Its ability to support nitrogen efficiency, correct soil pH, and improve yield quality makes it essential in modern agriculture. With widespread sulphur deficiencies and rising demand for higher crop productivity, sulphur fertilizers will remain a key component of sustainable farming systems. For fertilizer producers and buyers, choosing the right sulphur form and application method is critical to achieving both agronomic and economic benefits.