a1 Sustainable Agriculture Project Manager, Department of Crop and Soil Sciences, Washington State University, Pullman, WA 99164-6420.
a2 Professor of Soils, Department of Crop and Soil Sciences, Washington State University, Pullman, WA 99164-6420.
Our knowledge of soil is based primarily on quantitative analysis of isolated physical, chemical, and biological properties. However, the interaction of these quantitative aspects determines soil quality. Integrative tools are needed by researchers, farmers, regulators, and others to evaluate changes in soil quality from human activity at a local and global level. An index needs to be adaptable to local or regional conditions. For example, the parameters needed to determine changes in soil quality may differ between a semi-arid wheat field and a rice paddy. Suitable reference points and optimum ranges are needed for soil quality attributes. The present challenge is to integrate a suite of soiltests into a meaningful index that correlates with productivity, environmental, and health goals.