"Surface soils" refers to the top layer of soil that is closest to the ground's surface. It includes the soil that you see and touch, such as the dirt or mud on the ground. Full definition
They have incredibly long root structures, enabling them to pull incredible, intense nutrition from far below the depleted surface soil. (stylenectar.com)
For example, the report highlights a statement about decreases in surface soil moisture in the United States but leaves for the reader to unearth the statement that «Little evidence is found for a human influence on observed precipitation deficits.» (foxnews.com)
The spatiotemporal patterns of surface soil moisture in Northeast China based on remote sensing products (jwcc.iwaponline.com)