Answer to Question 1
The loss of humus and the consequent collapse of topsoil is referred to as the mineralization of the soil, because what is left is just the gritty mineral contentsand, silt, and claydevoid of humus. The loss of topsoil would mean the mutually supportive relationship between plants and soil is broken. When mineralization occurs, the soil is no longer able to support plants.
Answer to Question 2
Detritus is the food source for decomposers and detritus feeders. These organisms consume the detritus for energy and nutrients and release carbon dioxide, water, and minerals into the soil. The undigested portion of detritus excreted by the soil organisms is called humus. As minerals go through the guts of detritus feeders (e.g., worms), the minerals adhere to the humus. The clumps of humus create the structure of soil. The soil structure is the arrangement of soil particles. Humus improves a soil's ability to hold water and nutrients and increases its workability and aeration, while improving the ability of water to infiltrate the soil.
Water potentials decrease (become more negative) as one moves from soil to plant to atmosphere
Soil as Habitat
Soil and the terrestrial reservoir for carbon
Soil Conservation
Desert soil profile
The functional consequences of mutation