The Sulfur Cycle

The Sulfur Cycle

For various reasons, sulfur (S) deficiencies are increasing in many areas of the country. Consequently, fertility programs use this nutrient more routinely. The most common forms of S used in fertilizers are sulfate S (SO42–) and elemental S (S0). But these two forms of sulfur react quite differently in soils.

The most common S fertilizers are based on the addition of sulfate to the soil (e.g., gypsum, ammonium sulfate, potassium sulfate), as sulfate is the form by which plant roots take up S. Sulfate fertilizers are immediately available to crops, but are prone to leaching below the root zone.

Elemental sulfur is immobile and is not immediately available to plants. Plants simply cannot absorb S0 through the root system. Elemental S is inert and water insoluble. Fertilizers containing S0 must first be oxidized by soil microorganisms into sulfate for crop uptake. Elemental S is oxidized throughout the season into sulfate sulfur in order to provide season-long sulfur availability. At the end of the season, grain and or forage removal from the field necessitates the need to replenish this nutrient from the soil.

Using a fertilizer technology, like MicroEssentials, that contains and supplies S in both its readily available SO42– form and in a slowly released elemental sulfur form means that S is available for early seedling growth and development and as the growing season progresses, ensuring a season-long supply that matches crop demand.

  1. Apply fertilizer that contains both elemental and sulfate sulfur.

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  2. Sulfate S is immediately available to the plant, but is prone to leaching.

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  3. The sulfate S is taken up by the plant.

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  4. Elemental S is oxidized throughout the season into sulfate sulfur in order to provide season-long sulfur availability.

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  5. At the end of the season, grain and/or forage removal from the field necessitates the need to replenish this nutrient from the soil.

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Topics: Fertilizer Application, Macronutrients, Soil Fertility, Nutrient Removal
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