The book is out come of the research work carried during Doctorate thesis at Gobind Ballabh Pant University of Agriculture and Technology, Pantnagar, India. Sulphur (S), the fourth major plant nutrient, helps in protein production and chlorophyll formation. The yield and quality of crops is declining over time despite adequate supply of major nutrients (nitrogen, phosphorous and potassium) that might be due to deficiency of other nutrients including sulphur. Therefore, for assessment of direct and residual effect of S on wheat-rice and wheat-soybean cropping sequences, field experiments were conducted on two farmer's fields deficient in S in Tarai soils of Mollisols. The different parameters like crop yield, agronomic efficiency, apparent sulphur recovery and percent response, forms (total S, organic S, potassium di-hydrogen phosphate extractable S, sulphate S and non-sulphate S) and depth wise distribution of sulphur in soil and sulphur balance were assessed. Besides, how the sulphur affects the carbon, nitrogen and sulphur ratio (C: N: S) and the soil properties affecting the different forms of sulphur in soils of low, medium and high in sulphur content were also studied.