Soils

Question 1

What is soil?

Answer 1

an open system composed of weathered rock material and organic material (50%) and air and water (50%)

Question 2

What are the five factors of soil formation?

Answer 2

• parent material: the material the soil is derived from
• climate: temperature and moisture characteristics
• biological activity: vegetation, root systems, animals, microorganisms, etc.
• topography and slope orientation: level slopes have thicker soil; steep slopes have thinner soil
• time: the rate of soil development varies by parent material and climate

Question 3

How does agriculture impact soil?

Answer 3

soil building is a very slow process and poor farming practices can inhibit that process

Question 4

What are two sustainable farming techniques?

Answer 4

• contour plowing: farmers plow perpendicular to the slope of the hill to decrease runoff
• no-till agriculture: farmers leave crop stubble to reduce moisture loss and decrease soil erosion

Question 5

What problems does soil experience in dry environments (3)?

Answer 5

• desertification: the increasing expansion of desert territory, frequently caused by poor agricultural techniques
• salinization: build up of salt in the soil
• global climate change

Question 6

What is a soil profile?

Answer 6

a vertical section of soil from the surface down to the deepest roots

Question 7

What is a pedon?

Answer 7

the smallest unit of soil that contains all of the characteristics used in soil classification

Question 8

What are the six soil horizons?

Answer 8

• O: predominance of organic material; humus
• A: “topsoil;” much organic material
• E: sand/silt; leach-resistant materials
• B: accumulation of leach materials
• C: primarily weathered bedrock and parent material
• R: rock

Question 9

What are the six physical properties of soil?

Answer 9

• color: determined by chemical makeup of soil
• texture: the proportion of different particles of different sizes in the soil
• structure: the size and shape of different particles in the soil
• consistence: the cohesion of the soil
• porosity: the space between the soil particles which control the flow of air and water in the soil
• moisture: how much moisture the soil can contain