All of the major arable crops, including potatoes, sugar beet, tobacco, oilseed rape (canola), brassicas, alfalfa, wheat, barley, sorghum, maize, rice and cotton, are sensitive to a shortfall in soil sulphur levels.
Crops are affected directly by sulphur deficiency and indirectly because an alkaline pH decreases the availability of other nutrients, including phosphorous, potassium, calcium, iron, zinc, magnesium and manganese.
Significant yield losses can occur in low sulphur status soils of all arable crops and this is well documented in the scientific literature.
Typical sulphur requirements for some major arable crops
In cereals, a sulphur deficiency can also lead to lower protein levels in the grain, and given this affects the quality of the flour, the price received for this grain will be reduced.
In oilseed rape (canola) lack of sulphur will also affect the oil content and hence the price received for oilseed rape (canola).
The importance of sulphur can be summed up by looking at its effect, when in deficiency, on the world's oldest, most widely grown and traded staple crop - wheat - Triticum aestivum. Without some 20-30 kg sulphur/hectare, the normally grass-green wheat becomes yellow and yields slip, by anything from 200 to 1000 kg/hectare, depending on soil structure, weather, etc. But more than this, a short-fall in sulphur can drastically affect one of the essentials of life in communities throughout the world. For a well risen loaf of bread the baker requires flour rich in methionine and cysteine, and lack of these through sulphur deficiency in the bread wheat crop, reduces dough strength and loaf volume.
Increased milk production through better utilization of herbage
Sulphur deficiency is common in grassland, especially at second and later cuts in multi-cut silage systems using high rates of nitrogen. Deficiency is possible on all mineral soil types though is likely to be particularly severe on sandy and shallow soils and in areas of low atmospheric deposition.
Deficiency at first cut is less common but can occur on light sand and shallow soils. Grass on organic or peaty soils is not likely to show sulphur deficiency.
The symptoms of sulphur deficiency are a general paling of growth similar to nitrogen deficiency. Analysis of uncontaminated herbage sampled just before cutting is a useful indicator of deficiency. The information can be used to assess the need for sulphur for future cuts.
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