The series of critical reviews, Advances in Soil Science, fills a gap between scientific journals and comprehensive reference books. Scientists can delve into particular subjects. The series was formulated to be international in scope and to cover all subjects relating to soil science. Volume 10 contains contributions from scientists from Canada, the Philippines, and the United States on subjects relating to soil classification, nitrogen availability in forest soils, denitrification, nitrogen management in irrigated rice, and heavy metal solubilities in soils. The technical information herein will be invaluable for anyone concerned with optimizing crop production while conserving the soil as a resource.