Soil Layers
This term refers to a vertical section of soil consisting of horizons.
Soil profile
The horizon that is dark in color and contains the most organic matter.
A Horizon (Topsoil)
Dark soils are high in this type of organic material.
Humus (organic matter)
When soil particles cling together, they form these.
Peds
Good soil structure results in good aeration because it increases what?
Pore space
One factor that causes differences between soil layers, related to the arrangement of soil particles.
Particle arrangement
The horizon also known as the litter layer.
O Horizon
A soil that is gray in color indicates one of these conditions.
Wetness / lack of organic matter
The shape of a ped refers to this classification term.
Structure type
High organic matter increases both porosity and ____________________.
Water-holding capacity
Name any three properties that determine how horizons vary.
Any three: particle size, particle arrangement, color, parent material, drainage, organic matter content
This horizon is common for high clay content and lighter color.
B Horizon (Subsoil)
Brown or red soils indicate the presence of this element.
Iron
Name one structure type found in A horizons.
Granular
The term for the depth in which plant roots can grow easily.
Effective depth
This layer sits below parent material and is unweathered.
Bedrock (R Horizon)
The horizon formed from soft, weathered bedrock.
C Horizon (Parent Material)
Explain why dark soils are typically more fertile.
Dark soils contain more organic matter, which improves fertility and nutrient availability.
This structure describes large, vertically elongated peds, often with five sides.
Prismatic
List the four soil structure grades in order.
Strong, Moderate, Weak, Structureless
Explain how parent material influences the development of soil structure and texture.
should reference that parent material determines mineral makeup and influences texture, drainage, and later horizon formation.
Which horizon is best for root growth and why?
A Horizon, because it has high organic matter and aged minerals that support root development.
Soil color is mostly influenced by these two major components.
Organic matter and iron
Explain the difference between structure type and structure grade.
Structure type = shape of peds; Structure grade = how well the peds hold shape or how distinct they are.
Describe how organic matter contributes to improved soil structure at the microscopic level.
should mention organic matter binding particles into stable peds, improving aggregation, porosity, and structure.