Sulphur in crop production ¯¯ invited paper

The fact that crop deficiencies of sulpher (S) have been reported with increasing frequency over the past several years greater attention has been focused on the importance of this element in plant nutrition. In many regions in the world S deficiency has been recognized as a limiting factor for crop production. Especially in Western Europe incidence of S deficiency has increasingly reported in Brassica over the last decade. While sulphate in soil is a direct S source for plants, generally more than 95% of soil S is organic bonded and divided into sulphate ester S and carbon-bonded S. Although not readily plant available, organic S compounds may potentially contribute to the S supply of plants via mineralization. While sulphate esters play an important role in the short term release of sulphate, carbon-bonded S seems to be responsible for long-term mineralization. Predicting the S requirement of plants has become increasingly importance in European agriculture. To predict S delivery of soils different soil testing methods are suggested, which take the most important soil characteristics into consideration. It is suggested to elaborate a sulphur test in field experiments with the most sensitive crop in rotation, like oilseed rape. Besides soil test tissue analysis assist in identifying S deficiencies. However, in general they are used very seldom for making fertilizer S recommendations. To achieve high yields and to minimize S leaching, rates of fertilizer S should be recommended on the basis of available soil S and crop requirement.