A critical soil sulphur level for maize (Zea mays L.) grown in a glasshouse

Sulphur is an essential nutrient for the production of the amino acids cysteine and methionine, which are important for protein syntheses. Previous studies showed that sulphur deficiencies are becoming common because of the tendency to use more concentrated and liquid fertilisers. The objective of this study was determining the threshold concentration values for sulphur in different soils, above which no yield increase can be expected with increased sulphur fertilisation. Four soils, low in sulphur, were selected and treated with five sulphur levels. After four to five weeks the first deficiency symptoms appeared at the lowest sulphur levels. The plants were harvested after ten weeks. It was found that sulphur had a definite effect on yields and 10 mg kg-1 in soil can be used as a threshold value.