Precision: Spotting a Sulfur Deficiency Across All Plants

Precision: Spotting a Sulfur Deficiency Across All Plants


Sulfur (S) is supplied to plants from the soil by organic matter and minerals, but it is often present in insufficient quantities and at inopportune times for the needs of many high-yielding crops. Most S in the soil is tied up in the organic matter, and cannot be used by plants until it is converted to the sulfate (SO42–) form by soil bacteria.

When scouting crops, visual symptoms of sulfur (S) and nitrogen (N) deficiency are easily confused. For both N and S, mild deficiencies appear as stunted plants, with a general yellowing of leaves. Nutrients can be either mobile or immobile in the plant and understanding the level of phloem mobility can help to determine which part of the plant may express a nutrient deficiency. For example, as sulfur deficiencies worsen in corn, symptoms appear first in the younger leaves, demonstrating plant immobility. In contrast, nitrogen is mobile in the plant and expresses yellowing on the older leaves first, typically in a V-shaped pattern. In extreme cases of sulfur deficiency, younger leaves may even turn white. It is important to note that in minor deficiency situations, visual symptoms may not be noticeable at all, but can still be responsible for decreased yield. This is known as hidden hunger.

The best way to diagnose a deficiency is with a plant tissue analysis that includes both a sulfur and nitrogen test from a good and bad area of the field and addresses deficiencies accordingly.

Topics: Soil Fertility, Macronutrients
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