Soils are integral components of agro-, forest, and grassland ecosystems. They also influence watershed and coastal ecosystems, as well as urban ecosystems. Every management practice (timber harvest, fertilizer application, installation of irrigation or drainage system, application of biosolids) that we apply affects the soil and all soil organisms and higher plants growing in or on the soil. Likewise, the way how we manage plant communities affects the long-term stability and quality of the soils in which they grow. This section will introduce concepts of soil degradation, erosion, and soil quality.