The term "alkali soil"is employed to refer to soils that have a high exchangeable-sodium-percentage; and "saline soil" is used in connection with soils having a high value for the electrical conductivity of the saturation extract. This handbook was first issued in multilithed form in 1947, and it has been widely distributed in this country and abroad. The handbook is intended primarily as a practical guide for those who are confroted with soil, plant, and water problems involving salinity and alkali The first five chapters provide a basis for the evaluation and interpretaion of measure-ments The procedures and measuring methods given in chapters 6,7, and 8 are those with which the Laboratory has had experience, and they are believed to have general applicability in the diagnosis and improvement of saline and alkali soils. This handbook is the result of the combined efforts of the entire staff of the salinity Laboratry.