The sulphur distribution in relation to properties of black soil in northeastern China

Sulphur is an essential element for the crop growth. Black soil is one of the fertile soils in China, but sulphur deficiency has been reported in recent years. Sulphur content, forms and distribution in black soil were studied by determination of the soils sampled from three typical areas in the northeastern China. The main results obtained are as follows: 1)The average content of total S in 0-20cm depth in black soil is 405mg/kg, ranging from 190 to 1210mg/kg and 295mg/kg in 20-40cm depth, ranging from 160 to 690mg/kg. In the three areas tested, the total S content is in the order: Beian(north) Hailun(middle north) Gongzhuling(south); 2)Total S content in soil decreased apparently at earlier stages of reclamation and tended to be unchanged progressively; 3) Total S was significantly correlated to organic matter, CEC, clay and pH; 4)Total S decreased with the increasing of profile depth, but reached a peak in 145cm depth; 5)Three forms of organic S content (C-O-S, C-S and UO-S) accounted for 78% of the total S.