Yara recently announced plans to increase its production capacity of sulfur-enriched fertilizers at its plant in Sluiskil, the Netherlands. But, why is sulfur important for plants? Why isn’t there enough sulfur in the soil? Our Global Agronomist, Michael Basten, has the answers.

Sulfur is an essential part of many amino acids and proteins. It is one of the 16 elements essential for crop growth. Sulfur is also important for the protein quality of produces, and controls plant metabolism in enzymes. Plants take up sulfur in the form of sulfate. Because of the synergies between nitrogen and sulfur, it is most efficient to apply these two nutrients together. Learn more about crop nutrition.

 There are four main roles: 

1) Crops needs sufficient sulfate to make good use of nitrate nitrogen. 

2) Sulfur improves the protein quality. 

3) Sulfur enhances the taste, f. ex. in onions and cabbage, it adds pungency. 

4) Sulfur improves the protection mechanism against pests and diseases.

Sulfur deficient plants have yellow - green colored leaves. The discoloring is visible on younger leaves first. Overall growth, yield and harvest quality is reduced.

Picture of Yara Agronmist Michael Basten

Global Agronomist, Michael Basten - Based in Hanninghof, Dülmen, Germany. Years in Yara: 23 years.

Sulfur deficiency has become a main concern in modern-day agriculture. Twenty years ago, European farmers rarely encountered sulfur deficiencies in the soils. Today, however, it is a wide-spread problem. Until the late 1980s, industrial plants emitted large quantities of sulfur dioxide. This atmospheric sulfur was absorbed by the soil through rainfall (acid rain), thereby guaranteeing sufficient sulfur supply for plants. The adoption of emission abatement technologies by Europe's industrial sector led to a sharp drop in sulfur deposits from the atmosphere. The drop in sulfur dioxide emissions from industrial origins since the late 1980s, has been good for the soil since it has significantly reduced the acidification of the soil. Today, we are able to carefully adjust fertilization to the sulfur needs of the crops by adding the right quantity of sulfur to our products, thereby providing a balanced nutrition.

Whereas 20 to 30 years ago sulfur deposits were up to 100 kg per hectare/year, today they are only around 10 kg per hectare/year. Crops need between 10-40 kg of sulfur per hectare/year, so today the sulfur needs for many crops is no longer covered by the available sulfur supply in the soil. This is why farmers need to add this nutrient in the form of sulfate in mineral fertilizers. Our YaraVera Amidas product from Sluiskil, for example, contains sulfur in the form of ammonium sulfate, whereas the sulfur in our YaraBela product line comes either from calcium sulfate or ammonium sulfate.

The application of sulfur as part of the fertilization process increases crop yields by 10 to 30 percent on average depending on the crop. In trials in Canada, where the soil suffered from an extreme sulfur deficiency, the yield of oilseed rape was even doubled after applying10 kg S/ha.

Demand for sulfur in agriculture is growing by 2 percent a year in Europe. We estimate that global demand will continue to increase, hence the planned production capacity expansion in Sluiskil. With sulfur, we convert commodity fertilizers like urea and ammonium nitrate into differentiated products. The application of these fertilizers improves growers' profitability and allows us to increase margins and keep, or even increase our market share.