Ch.1 The Importance of Soil
The process by which carbon is recycled directly back to the atmosphere by plants and animals
Respiration
Water molecules join with the crystalline structure of minerals
Hydration
Soil characteristics that can be seen or felt
Physical property
Generate, absorb, or degrade greenhouse gases such as carbon dioxide, nitrous oxide, and methane
Microbes
Conversion of dry grasslands to desert
Desertification
Organic soils contain ____% or more organic matter.
20
Medium-sized particles; silky or powdery to the touch
Silt
Fungi that help plants absorb water and nutrients
Mycorrhizae
The process of storing carbon in soils, plants, or elsewhere
Carbon sequestration
Horizontal layers that develop as a soil ages
Soil horizon
Tend to occupy lower B and C horizons; peds are 1/5 to 4 inches, forming angular columns that stand upright in the soil
Prismatic structure
The ____ is an area of high biological activity that takes place close to the surface of the soil, near plant roots.
rhizosphere
Equal amounts of ____ and water are ideal for plant growth.
air
Soil formation
Soil genesis
Small particles; many small pores; consisting mostly of tiny sheet-like crystals
Clay
A large, diverse group of microscopic segmented worms that are especially numerous in soil.
Nematodes
Hardpans, water-logged soil, and ____ prevent roots from growing deeply.
bedrock
Minerals react with the hydrogen in water molecules and split the water
Hydrolysis
The measure of the rate of water movement through a soil
Hydraulic conductivity
Some fix nitrogen and some produce antibiotics
Actinomycetes