What exactly is soil degradation?

The answer

Soil degradation is a decline in the soil's ability to support plants, store and filter water, cycle nutrients and shelter living organisms. FAO's soils portal describes it as a change in soil health that diminishes the capacity of the ecosystem to provide its normal goods and services. It can involve physical damage such as erosion and compaction, chemical change such as salt build-up or acidification, or loss of organic matter and soil life, and often all three happen together.