Smart Sulfur Fertilizers Swellable Granules Maximize Nutrient Availability

Soil sulfur is an essential nutrient that many crops need for optimal growth and yield, yet sulfur availability in many agricultural regions is declining. The challenge isn’t adding sulfur to fertilizers-that’s straightforward chemistry. The real problem is making that sulfur available to plants. Elemental sulfur must oxidize in the soil to become plant-available sulfate, but the process is slow and uneven. This patent describes an elegant solution using swellable hydrogel technology to increase sulfur surface area and accelerate oxidation rates, transforming elemental sulfur from a marginal nutrient supplement into an effective and efficient crop input.

The Problem

Modern agriculture removed atmospheric sulfur deposits as a consequence of environmental regulations that reduced industrial pollution. This eliminated a major source of sulfur that had previously supplemented soil reserves. Simultaneously, crop breeding has pushed plant genetics toward increased yields and quality characteristics that demand more sulfur than heritage varieties required. The result is widening sulfur deficiency in soils worldwide, particularly in regions using intensive farming practices.

Elemental sulfur can address this deficiency, but not immediately. Plants require sulfate, the oxidized form of sulfur. Elemental sulfur particles must first undergo microbial and chemical oxidation in the soil-a process that’s slow, temperature-dependent, and spatially uneven. In cool weather, sulfur oxidation nearly stops. Even in warm conditions, sulfur particles sitting in tightly compressed granules oxidize inefficiently because microbial colonization and oxidation occur only at the particle surface.

Fertilizer formulations typically address this by mixing elemental sulfur with other nutrients to create a complete fertilizer. But again, the sulfur’s slow availability is the bottleneck. The crop may finish its primary growth phase before oxidized sulfur becomes available in meaningful quantities, resulting in suboptimal yields and quality.

What This Invention Does

This patent describes fertilizer granules containing elemental sulfur combined with hydrogel technology. The hydrogel, which expands or swells as it absorbs water in the soil, serves a critical function: it disperses the elemental sulfur throughout a much larger volume of soil, multiplying the particle surface area exposed to oxidizing conditions.

When the hydrogel absorbs soil moisture, it swells, physically separating sulfur particles and distributing them into the expanded gel matrix and surrounding soil. This dramatically increases the surface area available for microbial colonization and oxidation. The result is faster, more efficient sulfur oxidation and earlier plant availability.

The innovation describes two manufacturing approaches: coating elemental sulfur and hydrogel onto a base fertilizer granule, or co-granulating them together to form an integrated product. Both achieve the same result: sulfur that oxidizes more readily and becomes plant-available earlier in the growing season.

The patent notes this is a divisional application, indicating Mosaic’s systematic development of swellable fertilizer technology with progressively refined embodiments and claim structures addressing different application methods.

Key Features

Increased Surface Area Availability. The swelling action of the hydrogel disperses sulfur particles into and around the expanded gel matrix, exposing far more particle surface to soil conditions. This single innovation can increase oxidation rates by multiples.

Accelerated Oxidation Timeline. More available surface area plus increased water and microbial contact directly translate to faster sulfur oxidation. Elemental sulfur that might take months to become available under traditional granule conditions becomes plant-available in weeks.

Flexible Manufacturing Integration. The sulfur-hydrogel combination can be added to fertilizer formulations either as a surface coating or as co-granulated material, allowing producers to modify existing granule designs without complete production line redesign.

Enhanced Nutrient Synchrony. By accelerating sulfur availability, the formulation achieves better alignment between sulfur availability and crop demand. Sulfur becomes available when plants need it during growth phases that benefit from this nutrient.

Applicable to Various Fertilizer Types. The innovation works with any base fertilizer composition, making it compatible with both conventional NPK fertilizers and specialty products for different crop types.

Who Is Behind It?

The Mosaic Company, one of the world’s largest fertilizer producers based in the United States, brought together four inventors: Michael McLaughlin, Jozefien Degryse, Roslyn Baird, and Rodrigo Coqui Da Silva. This patent claims priority to a U.S. provisional application from May 23, 2017, and builds on divisional patent 2023270222, demonstrating Mosaic’s sustained innovation in fertilizer technology.

Why It Matters

Global agriculture faces simultaneous pressures to increase productivity while reducing environmental impact. Sulfur deficiency is increasingly recognized as a constraint on crop yields and quality in many regions. Products that make sulfur fertilizers more effective directly improve farm economics and enable higher production from existing land.

The technology is particularly important in regions where sulfur deficiency has become widespread-parts of North America, Europe, and other developed agricultural regions where atmospheric deposition is minimal. Farmers in these regions actively seek effective sulfur products, creating a ready market for innovations that improve sulfur availability.

From an environmental perspective, better utilization of applied sulfur means less product needed to achieve the same nutrient availability, reducing overall chemical loading on soils. The hydrogel approach represents efficient nutrient management aligned with sustainability goals.

The fertilizer market is enormous-exceeding 100 billion dollars globally-and innovations that improve nutrient efficiency have substantial commercial potential. The IPC classifications (C05G 3/00, C05G 1/00) confirm this is fertilizer science at a significant level of innovation and functionality.

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AU 2026201411 was published in the Australian Official Journal of Patents on 19 March 2026 and is open for public inspection. Patent applications represent inventions that are sought to be protected and do not necessarily reflect commercially available products.

Related Concepts

Hydrogels are water-absorbing polymer networks that can swell to many times their original volume, making them useful in agriculture as soil conditioners and controlled-release carriers. Sulfur deficiency has become a growing challenge in modern agriculture as clean-air regulations have reduced atmospheric sulfur deposition that historically supplemented soil reserves. Together, these trends are driving innovation in fertilizer technology – particularly slow-release formulations that synchronise nutrient availability with crop uptake windows.