Fall sulfur application: Selecting the best product
Sulfur has become an important crop nutrient applied to corn fields across Minnesota. Recent research has shown a benefit from applying sulfur in fields low in organic matter and in high residue situations where mineralization and release of sulfate sulfur from organic matter are limited. What can make sulfur application challenging is that the form of sulfur available for crop uptake is sulfate. Sulfate is an anion and, like nitrate, can leach deep in the soil profile where crop roots cannot reach. The addition of sulfur fertilizers to fall phosphorus and potassium applications leads to questions about what the best form of sulfur is. Choosing the right form is critical to ensure crops are not short of this necessary nutrient early in the growing season. Commercial sulfur fertilizer sources include either elemental or sulfate forms of sulfur. The difference between the two is that sulfate sulfur forms, such as gypsum or ammonium sulfate, contain readily available sulfur, while ele