Exam 2

Question 1

Be able to describe the basics of the color description system for soils

Answer 1

There’s three main components of the Munsell System
Hue - specific color
Value - lightness/darkness
Chroma - color intensity

Question 2

How do you find the hue?

Answer 2

It’s the value number / chroma

Question 3

What affect does increasing organic matter have on soil color?

Answer 3

Organic matter is darker because of all the carbons. (same thing with the degree of wetness)

Question 4

What sorts of thing would the variety of color of the soil tell you?

Answer 4

The red/yellow leaning shows the state of oxidation
The darker colors have a chance to represent the presence of organic matter

Question 5

What is a gleyed soil?

Answer 5

When low oxygen soil conditions (such as a high water table) cause Iron and Manganese to reduce and ultimately make the soil grey

Question 6

What is the difference between particle size and structure in a soil?

Answer 6

Soil structure is how the soil particles all together are arranged/held/structured while the particle size refers to the size of the individual soil particles

Question 7

What is the relationship between mineralogy of the parent rock and the dominant particle size of the soils?

Answer 7

Well, the parent material determines what is more commonly present in the soil
If the parent material is more resistant, it will be hard to wear it down

Question 8

Feeling good with a soil triangle?

Answer 8

Yep!

Question 8

What are soil aggregates?

Answer 8

It’s a group of soil particles that have stuck/cohered together more strongly than the other soil particles
It’s typically clay sticking together
The space between the aggregates provides pore space which can hold more air and water

Question 8

What is mineral density?

Answer 8

A measure amount of minerals contained in a certain volume of the soil

Question 8

What is soil bulk density? How is it calculated

Answer 8

Bulk density is the oven-dried weight of soil per volume of unit at the field moisture capacity

Question 9

Is it better to have a higher or lower bulk density in a soil or does it depend on what the soil is used for?

Answer 9

Obviously it depends
higher bulk density can head to poor soil structure, reduced water infiltration, root growth
low bulk density indicates a more porous and aerated soil has better root growth and water retention

Question 10

What is the shrink-swell potential of soil?

Answer 10

The volume change that occurs as a result of changes in the moisture content of clay-rich soils
Causes structures to come in and out of the soil and lean

Question 11

What are the different subsurface “zones” for water?

Answer 11

There’s the unsaturated and saturated zone with the water table in the middle

Question 12

How does the water content vary in these different zones?

Answer 12

The saturated zone has more water?

Question 13

Is there a typical direction of water flow in soils?

Answer 13

It flows from high pressure to low pressure

Question 14

What are the different types of forces or potentials that drive the direction of water flow?

Answer 14

Pressure forces
Capillary forces

Question 15

Which particle size usually contains the most water per unit of water potential?

Answer 15

Clay

Question 16

How does the degree of compaction and bulk density affect the water content of a soil?

Answer 16

Compaction increases bulk density and decreases total pore space, reducing available water capacity