Sulphur Content and Distribution in Paddy Soils of South China

Abstract

In the hilly areas of South China, where the content of available sulphur in paddy soils usually appears low, farmers used to dip the roots of rice seedlings into a suspension of gypsum or sulphur before transplantation. Old practice has been proved beneficial to the growth and yield of rice plant. Over recent decades, most of the S-containing fertilizers, such as (NH₄)₂SO₄ and superphosphate have been replaced by NH₄HCO₃, urea and alkaline fused rock phosphate. The return of plant ashes to agricultural field, which is actually a complete mineral fertilizer, has been greatly reduced and the most of the K-fertilizer is given in the form of KCl. Thus, the elimination of sulphur-containing fertilizers induces the expanding of sulphur deficiency areas. On the other hand, owing to the increasing yield of rice, the removal of soil sulphure by the crop has also increased and consequently more sulphur fertilizer is needed.