Continuing the international tradition, Volume 49 of Advances in Agronomy highlights current areas of interest to both researchers and students of agronomy. Areas covered include phosphogypsum in agriculture, nutrient cycling and soil fertility in the grazed pasture ecosystem. It also discusses the current use of computer assisted tomography (CAT) in studying water movement around plant roots as well as future applications of CAT in agronomy, and electrical conductivity methods for measuring and mapping soil salinity.