Lecture 19: Soils

Question 1

What is MN’s state soda?

Answer 1

Lester (loam soil) found in south-central MN

Question 2

What type of soil do tubers like?

Answer 2

Sandy soil

Question 3

What type of soil do corn, wheat, and soybean like?

Answer 3

Silt loam (60% silt, 20% clay, 10% sand)

Question 4

What is soil texture?

Answer 4

Combinations of 3 soil particles (sand, silt, clay)

Question 5

Which soil particle holds the most nutrients?

Answer 5

Clay

Question 6

Drainage, aeration, and penetration (order particles from most to least)

Answer 6

1. Sand
2. Silt
3. Clay

Question 7

What determines soil types of an area?

Answer 7

Climate, topography, and crops planted

Question 8

What is loam?

Answer 8

A soil texture

Question 9

Cation

Answer 9

Positively charged

Question 10

Aggregation

Answer 10

“clumps of soil”

Question 11

Why do soil aggregates need holes?

Answer 11

So H2O, and gases can pass through (O2 availability and CO2 ventilation)

Question 12

What happens when soil is water logged?

Answer 12

CO2 build up

Question 13

What is tilth?

Answer 13

soil that holds water and nutrients, but also has good drainage and gas exchange

Question 14

Two ways to improve soil structure:

Answer 14

1) increase organic matter

2) decrease soil compaction

Question 15

Why can tillage be bad?

Answer 15

It exposes organic matter to O2 which degrades and can no longer hold aggregates together, leading to soil compaction

Question 16

What does soil organic matter refer to?

Answer 16

Carbon-based material in soil from plants, animals, microbes, etc.

Question 17

What is humus?

Answer 17

Transformed former living organisms into soil (can hold up to 6x its weight in water)

Question 18

Why does humus have a good electro chemical charge?

Answer 18

Organic matter is negatively charged and so it holds positively charged cations in calcium (important for plant growth)

Question 19

4 ways organic matter can be added to soils:

Answer 19

1) compost
2) raw organic matter
3) green manure
4) incorporating crop residues

Question 20

What is compost?

Answer 20

Decomposed organic matter added to soil

Question 21

What is raw organic matter?

Answer 21

uncomposted material is tilled into soil (more nutrients in the long run)

Question 22

What is green manure?

Answer 22

Crops grown with the sole purpose of being tilled into the land to increase organic matter

Question 23

How does one incorporate crop residues into soil?

Answer 23

bare minimum or no till…just plant right over residue in the spring

Question 24

How long must a field be out of conventional farming before it is considered organic?

Answer 24

3 years

Question 25

What do the numbers on a bag of fertilizer mean?

Answer 25

Nitrogen-Phosphorous-Potassium content