Organic wastes are traditionally applied to land to recover their fertilizer value, but the microbial turnover of such organic matter in soil is often out of phase with the requirements of growing plants. Therefore, nutrients may be lost and may even act as potential pollutants of water and air, posing a particular challenge to agricultural and environmental engineers.This book addresses both experimental and modeling methodology under the main headings of nitrogen and carbon transformations, gaseous losses, chemical means of controlling nitrification, and nitrate leaching. The articles are based on material presented at a specialized seminar held under the auspices of ISWA and DAKOFA at Aalborg University, Denmark, in September, 1988.

The Cary Conferences, as we have envisaged them, are different from most scientific meetings in that they provide a forum for major issues in ecology from a more philosophical point of view. It appears to many of us that ecologists have limited opportunities to come together in small groups to address in a more philosophical way some of the major questions and issues that matter very much to the future of humankind and to us as ecologists. Moreover, we hope that the setting ofthe Mary Flagler Cary Arboretum promotes strong interaction and dis cussion between Conference participants with a minimum of distraction. We are proud to make our facilities available for such meetings, and we hope that over the years these Conferences might provide direction and leadership for the whole field of ecology. We have the broad goal of attempting to advance the field of ecology by bringing together leading ecologists and other scientists to address major issues. The first Cary Conference, in 1985, considered the status and future of ecosystem science. This first Conference was rather loosely structured but was successful in stimulating discussion, ideas, and enthusiasm (Likens et al. , 1987). The goals for this second Cary Conference in 1987 were: 1. to identify the roles of long-term studies in ecology; 2. to identify the options for study of long-term ecological phenomena; 3.