In modern agriculture, having just water and soil is no longer enough; proper soil nutrition is the key to achieving high-yield and high-quality crops. One of the essential elements that has naturally decreased in soils in recent decades—due to factors such as soil erosion, leaching, and reduced organic matter—is sulfur. The deficiency of this element not only hinders plant growth but also disrupts the absorption of other nutrients. Among the solutions, granular sulfur has emerged as a scientific, sustainable, and effective answer, earning a place among the best soil amendment fertilizers. If you are also looking to enhance your farmland, stay with us in this article by Faraz Oil.
Granular Sulfur Production Method
Granular sulfur can be considered a refined petroleum by-product that, when combined with specific additives, is transformed into a form that is absorbable by plants or usable in various industries. In fact, the sulfur used in producing granular sulfur is usually extracted during the refining process of crude oil and natural gas. This material is obtained as a by-product of the desulfurization process, which aims to reduce the sulfur content in oil and gas to prevent environmental pollution. After extraction, the raw sulfur is melted and then mixed with substances like bentonite to be transformed into solid and stable granules. This form is more stable and more practical for agricultural and industrial applications.
What Is Granular Sulfur Fertilizer?
As explained above, granular sulfur fertilizer is a chemical fertilizer composed of compact and granulated particles, typically made by combining elemental sulfur with bentonite or other swelling agents. This fertilizer swells upon contact with soil moisture and gradually releases sulfur particles into the soil. The bentonite acts as a swelling agent, helping sulfur to break down more uniformly and efficiently, thus increasing its absorption by plant roots.
In terms of composition, this fertilizer usually contains 75% to 90% sulfur and 10% to 25% bentonite. Its granulated form makes it easier to transport, store, and spread evenly across the field, and it has greater resistance to wind and leaching compared to other forms of sulfur fertilizer.
What Is the Difference Between Granular, Powdered, and Liquid Sulfur?
Powdered sulfur generally reacts more quickly in soil, but due to its light weight and high dispersion, using it over large areas is challenging. It may be blown away by wind or washed away by rain before the plant can absorb it. Additionally, it oxidizes rapidly, increasing the risk of sulfur loss before plant uptake.
In contrast, liquid sulfur is mostly used for foliar spraying and has limited root absorption. On the other hand, granular sulfur provides a slow and controlled release, offering plants long-term access to sulfur and leading to a more stable improvement in soil pH and structure.
Bentonite granular sulfur comes in various types with different ratios of sulfur (typically 70% to 90%) and bentonite (10% to 30%). Each type can be selected based on soil type, plant needs, and the method of application. These characteristics make it an ideal choice for amending alkaline and calcareous soils.
How Does Granular Sulfur Work in Soil?
After being applied to the soil, granular sulfur swells due to moisture. The bentonite in the granules helps facilitate the gradual breakdown of sulfur. In this process, sulfur is first converted into elemental sulfur and then, with the help of microorganisms such as Thiobacillus bacteria, it is transformed into sulfate, the absorbable form for plants.
The presence of bentonite in the fertilizer helps retain moisture around the sulfur particles, which enhances the speed and uniformity of oxidation. As a result, sulfur is released slowly, providing a continuous effect on soil and plant health. This slow-release function not only boosts efficiency but also prevents sulfur loss through leaching.
Benefits of Granular Sulfur in Agriculture
Thanks to its smart combination of sulfur and bentonite, granular sulfur offers numerous advantages for both soil and plants, making it one of the most effective fertilizers in agriculture.
1. Amending Alkaline and Calcareous Soils
One of the key benefits of granular sulfur is its ability to reduce soil pH. In many regions, soils are naturally alkaline, which prevents the roots from absorbing many essential nutrients. Granular sulfur gradually releases sulfur and converts it to sulfuric acid, causing localized acidification of the soil and enabling better nutrient absorption—especially effective in calcareous and saline soils.
2. Increasing Access to Nutrients
Sulfur plays a crucial role in improving the availability of key nutrients such as nitrogen, phosphorus, potassium, iron, manganese, and zinc. When soil pH decreases, these nutrients shift from insoluble forms to forms that roots can absorb. As a result, plant nutrition improves significantly and signs of nutrient deficiencies decrease.
3. Improving Soil Structure
Using granular sulfur helps enhance soil porosity and aeration. The bentonite content improves the soil’s ability to retain water and makes it softer and more permeable. This is especially beneficial in dry regions or heavy soils, where water and air penetration to the roots is often a challenge. It also boosts biological activity in the soil.
4. Enhancing Plant Growth and Product Quality
Granular sulfur fertilizer creates optimal conditions for nutrient uptake, resulting in faster and stronger plant growth. It also increases protein content in grains, oil content in oilseeds, and flavor in fruits and vegetables. Many crops such as garlic, onions, and radishes, which have strong taste and aroma, rely heavily on sulfur.
5. Antifungal and Soil Disinfectant Properties
Another important benefit of granular sulfur is its ability to control soil fungal diseases like powdery mildew. Sulfur creates an acidic and disinfecting environment that is unfavorable for fungi and some pests. This function not only protects plant health but also reduces the need for chemical pesticides.
6. Stimulating Beneficial Microbial Activity in Soil
Due to its organic content and bentonite base, granular sulfur fosters an environment conducive to beneficial soil bacteria and fungi. These microbes play a key role in decomposing organic matter and releasing nutrients. Moreover, the conversion of sulfur to sulfate is carried out by these bacteria, leading to improved soil fertility and biological health.
How to Use and Apply Granular Sulfur
To achieve the best results with granular sulfur, the timing and method of application are crucial. The ideal time for application is usually late autumn to before planting, or in the early growing season. During these periods, the soil is most prepared to absorb nutrients, and microbial activity is high.
The method of application also varies depending on the type of crop. Granular sulfur can be applied through surface broadcasting, banding near tree roots, or mixed with animal manure.
Recommended application rates vary by field and soil conditions:
- In orchards: About 1 to 3 kilograms per tree
- In field crops: 500 to 1000 kilograms per hectare
- In greenhouses: Around 250 grams per square meter
For better results, it is recommended to till the soil after applying the fertilizer to ensure proper mixing and maximize nutrient absorption.
Conclusion
In modern, high-yield agriculture, sulfur is no longer optional; it is an essential and vital element for maintaining productivity, crop quality, and soil health. The use of bentonite granular sulfur, with its slow-release mechanism, soil stability, and effectiveness in amending alkaline soils, represents a scientific and proven approach to plant nutrition management.
It is highly recommended to test your soil before using this fertilizer and to consult with agricultural experts to determine the exact dosage and timing. Choosing the right type of sulfur and using it strategically can significantly boost your land’s productivity. You’ve been reading this article in collaboration with Faraz Oil, a producer and supplier of petroleum-based products.