ABSTRACT
Soil, the thin layer of unconsolidated material that covers the Earth’s surface, is a natural resource that is perhaps uniquely responsible for human development and continued existence on this planet. Humans require food, water, shelter (including clothing and housing), and a means to separate themselves from their own waste products. Soil is the main reservoir that supplies water and essential nutrients for the growth of plants for food, fiber for clothing, and forests for building materials. At the same time, soil is the principal receptacle for waste material, including human, animal, and industrial wastes. Soil is expected to filter and process human and animal waste products, and to tie-up or degrade industrial waste substances to prevent toxic materials from being transferred back into the food chain and drinking water supplies. However, land development and population growth continue to consume and overtax soil resources such that productivity requirements and environmental demands require an increasingly precise level of management to optimize the performance of soils.
