John Stewart was a soil scientist at the University of Saskatchewan. He was born in Northern Ireland on January 18, 1936. He received his BSc, BAgr, and PhD at Queen's University, Belfast, and was later awarded a DSc from that university in 1988. Stewart came to the University of Saskatchewan in 1964 as a post-doctoral fellow in the Department of Soil Sciences. After joining the Department in 1966 he moved up through the academic ranks to become Head of Soil Sciences from 1981 to 1989, and then Dean of Agriculture from 1989 to 1999. He was recognized internationally for his research in soil science. His early research focused on phosphorus and sulfur cycling in geo-ecosystems; this led to the development of conceptual and predictive simulation models for phosphorus and sulfur in soil-plant systems, and to predicting the effects of climate change and land-use changes on ecosystems. His publications were wide-ranging, and his work extended to the United States, Brazil, the Philippines, Ghana, Nigeria, and the United Kingdom. Stewart has served on numerous national and international boards and committees, including the Scientific Committee on Problems of the Environment. His numerous awards include: fellowships from the Canadian Society of Soil Science (1987), Wissenschaftskolleg zu Berlin (the Berlin Institute of Advanced Study, 1989), and membership in the American Society of Agronomy (1990) and the Soil Science Society of America (1990).