http://www.vasat.icrisat.org/?q=node/142

It is only recently that deficiency of sulfur has become common in groundnut. The recent use of high analysis fertilizers like Di-Ammonium Phosphate (DAP) and organic pesticides containing very little sulfur is resulting in sulfur deficiency. Sulfur deficiency is characterized by stunted growth, and general yellowing of plants. In some cases and interveinal pattern appears, the veins remaining green. Sulfur deficiency may also delay maturity of groundnut crop. An acute sulfur deficiency causes the entire plant to turn yellow.

Yellowing of leaves also is characteristic of nitrogen deficiency.   But, in this case, yellowing always starts with older leaves (bottom leaves) and proceeds upward   . On the contrary, yellowing of leaves due to sulfur deficiency is more marked in the younger leaves (top leaves).