Fertile soil is valuable because there is a limited supply. Less than one eighth of land on Earth has soil that are well suited for farming.
The thick, fertile soil of the prairies took many thousands of years to develop.
The two ways that the value of soil can be reduced is help use soil correctly, peanuts were once a corp to help soil, and still can be. The soil value recycle rocks and bedrock.
The value of soil is reduced when it loses its fertility and when topsoil is lost due to erosion. Soil can be conserved through contour plowing, conservation plowing and crop rotation. The thick mass of tough roots at the surface of the soil.