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Sulfur (S) is a secondary nutrient, but it can be just as important as the primary (macro) nutrients. In fact, a plant’s sulfur requirements are similar to its needs for phosphorus, which is why some people call it “the fourth macronutrient.”

Sulfur is essential for plant growth, aiding in enzyme and vitamin activities, chlorophyll formation and nitrogen stabilization. It is an integral part of several amino acids which are essential for protein production and is necessary for nodule formation in legumes.

Another benefit to sulfur is its usefulness as a natural fungicide. It is highly effective at preventing and controlling biotropic fungi and powdery mildews, which can have a significant effect on crop health and yield.

Cereals, oilseeds and legumes can be sensitive to sulfur deficiency. Baking quality in wheat crops and oil content in some oilseed crops can be adversely affected by a deficiency of sulfur.

Deficiency symptoms present similar patterns to those of nitrogen deficiency, with uniformly pale green or yellow leaves; however, a sulfur deficiency will start in the new leaves, due to sulfur’s immobility within the plant. Purpling of interveinal areas and margins is also common on both young and old leaves. In legumes, nodules are smaller and pale, rather than pink, and the number of nodules is reduced. In flowering canola, sulfur deficiency manifests as pale petals and low oil content.

Sulfur is easily leachable and is often deficient in acidic, sandy soils, especially in areas experiencing heavy rain. Continuously cropped soils and soils low in organic matter also tend to be low in sulfur; however, even in soils high in organic matter, amendments may be required if the mineralization process is slowed, limiting available sulfur.

The Solution

To prevent or correct a sulfur deficiency, try Foliar Supreme, S720 or Thio-S56 liquid foliar fertilizers. These highly concentrated suspensions and solutions contain nitrogen, phosphorus, potassium and sulfur and are safe for foliar application even when humidity is low, and temperatures are high.

Foliar Supreme, designed for maximum uptake and utilization with 33 per cent sulfur, and S720, containing 51 per cent sulfur in a highly available form, can be used on a variety of crops. Thio-S56, on the other hand, is a solution that allows the correction of sulfur deficiency at any stage of the crop. Expect higher oil content in oilseed crops and higher protein with better milling and baking performance in wheat.

Talk to your retailer or OMEX sales representative for more information on a plant nutrition program, tailored to your crop’s unique requirements.

In our next post: Calcium – the building block of cell walls.