Satya Prasad Raychaudhuri obtained DSc (1932) from University of Calcutta; and another DSc (1945) from University of London, UK. He was Head, Division of Soil Science and Agricultural Chemistry (1949-50), Chief Soil Survey Officer (1958-61), Indian Agricultural Research Institute (IARI), New Delhi; Senior Specialist (Land Resources), Planning Commission (1961-69); and also Chief Agronomist, Shriram Khad Programme, New Delhi.

Academic and Research Achievements: Dr Raychaudhuri initiated research on red and lateritic soils in India, prepared the soil map of India and initiated soil- and land- use survey. His work on soil testing and the use of balanced fertilizers led to the development work in these fields. His study on agriculture in ancient India led to the publication of several books and bulletins on the subject. Along with Professor JN Mukherjee, Raychaudhuri was pioneer in the field of colloid chemistry. Their work established that colloids possess electrochemical properties; the charges on colloid particles are influenced by electrolytes and non-electrolytes and are responsible for their absorptive properties. These observations led to the postulation that soil colloids possess colloidal properties and the cation exchange phenomenon of soil can be explained on the basis of charges on soil colloids. Still significant is the finding that soil acidity was due to the presence of exchange hydrogen and aluminium ions on the surface of soil colloidal particles.

Other Contributions: Dr Raychaudhuri served as Member of the Indian Chemical Society, Indian Society of Agricultural Chemists, Soil Conservation Society of India, Soil Conservation Society of America, Indian Society of Agronomy, Royal Institute of Chemistry, London, and World Academy of Arts and Science. As Secretary of Indian Society of Soil Science, he started a journal - Journal of the Indian Society of Soil Science in 1953.

Awards and Honours: Dr Raychaudhuri was elected Fellow of the National Academy of Sciences (India), Allahabad; President, Agricultural Sciences Section, Indian Science Congress (1955-56) and International Society of Soil Science; and Honorary Member, USSR Society of Soil Scientist. Lectureship awards won by him include: Baradanada Chatterjee Memorial Lecture (1975); RV Tamhane Memorial Lecture (1977); and JN Mukherjee Lecture by Indian Society of Soil Science (1983).