Technical Abstract: This is a preface to a Special Issue of Geoderma, entitled 'Quantifying Agricultural Management Effects on Soil Properties and Processes'. The issue presents the state-of-the-science research and synthesis of knowledge on this subject, in order to stimulate further research in this area. Contributions of a leading international group of scientists on various aspects of the subject also include many more needs and much greater challenges that lie ahead. The Preface provides a list of important areas for predictive research in the future.