|Sulfur deficiency symptoms in corn|
Although S exists in many different chemical forms in nature, plants primarily absorb it in the SO4 form. The SO4 molecule carries a negative charge, so it moves freely with soil moisture. As a result, SO4 concentrations are sometimes greater with increasing depth in the soil below the rootzone. There are several excellent sources of plant-available SO4 that will provide immediate crop nutrition. These include materials such as potassium-magnesium sulfate, ammonium sulfate, or potassium sulfate.
|Large particles of sulfur will be slow to convert to sulfate|
The physical properties of elemental S are also important. Small-sized particles have the most surface area and the most rapid reaction. However, fine particles of S can be difficult to apply. Fertilizer manufacturers have developed useful techniques where very fine S particles are clumped together with expandable clay to form a pellet which disintegrates in the soil.
|Dr. Tim Hartz examines sulfur pastilles|
Thiosulfate has also become a popular source of S nutrition for crops. Thiosulfate generally converts to SO4 within a few weeks in typical summer growing conditions. Thiosulfate has also been shown to have beneficial effects on N transformations and may offer some unique benefits for plant metabolism.
|Sulfur burners are sometimes used to treat irrigation water with high concentrations of bicarbonate|