Chapter 10: Farming: Conventional and Susatainable Practices

Question 1

How many millimeters can severe erosion take off of soil?

Answer 1

25 mm

Question 2

What are the six components of soil?

Answer 2

1: Sand and Gravel
2: Silts and Clays
3: Dead Organic Material
4: Soil Fauna and Flora
5: Water
6: Air

Question 3

What are some variations of soil?

Answer 3

1: Abundant clay makes soil sticky and wet
2: Abundant organic material and sand makes the soil soft and easy to dig
3: Sandy soils drain quickly, depriving plants of moisture
4: Soils with abundant soil fauna quickly decay dead leaves and roots, making nutrients available for new growth
5: Compacted soils have fewer air spaces, making plants grow poorly
6: Reddish, iron-rich soils, including most tropical soils store few nutrients for plants
7: Deep, black soils are rich in dead organic material, which makes the soil rich in nutrients

Question 4

What is one of the most important characteristics of soils?

Answer 4

Soil texture

Question 5

What does the texture of a soil help determine?

Answer 5

Whether rainfall drains away quickly or ponds up and drowns plants

Question 6

What is one major geographical example for each red soil and black soil?

Answer 6

Most Brazilian tropical soils are red clays

The Corn Belt of the central U.S. has rich, black soil

Question 7

What is micorrhizal symbiosis?

Answer 7

An association between the roots of most plant species and certain fungi. The plant provides organic compounds to the fungus, while the fungus provides water and nutrients to the plant.

Question 8

In what layer of soil do most plants grow ?

Answer 8

The “O” or organic layer

Question 9

What layer of soil is below layer “O” and consists of mixed organic material and mineral soil material ?

Answer 9

The “A” horizon or surface soil

Question 10

What layer of soil is below layer “A” and is made up of richer clays than “A” and accumulates clays that seep through layer “A”?

Answer 10

The “B” layer or subsoil

Question 11

What is the “E” layer of soil and what is it made of?

Answer 11

The “E” layer is the rare layer between layers “A” and “B”. It is made up of clays and organic materials that are light-colored

Question 12

What layer of soil is below the “B” of soil and is made up of decomposed rock fragments ?

Answer 12

The “C” layer

Question 13

What layer of soil is below the “C” layer?

Answer 13

Parent material: The sand, windblown silt, bedrock, or other material on which the soil is built.

Question 14

What percentage of parent rock in the U.S. was put there by glaciers, wind, and water?

Answer 14

About 70%

Question 15

Under the best circumstances, at what rate does topsoil accumulate every year?

Answer 15

1 mm per yearly

Question 16

according to the U.S.D.A, how many different types of topsoils are there?

Answer 16

11 types

Question 17

What is the dominant soil type in the U.S. Corn Belt?

Answer 17

Mollisols (mollic=soft, sol=soil)

Question 18

What are two other and different types of topsoils other than mollisols?

Answer 18

Aridisols and alfisols

Question 19

What two topsoil types dominate most of the farming regions in the U.S?

Answer 19

Mollisols and alfisols

Question 20

What percentage of Earth’s land area is currently being used for agricultural production?

Answer 20

12.5% (or 16.6 out of 132.4 million km squared)

Question 21

How many hectares are being subject to wind and water erosion each year?

Answer 21

More than 43.7 million hectares (108 million acres)

Question 22

Where do the best agricultural lands occur?

Answer 22

Where the climate is not too cold or too dry, also where thick and fertile soils are found

Question 23

In developed countries, from what combination of things has 95% of agricultural growth in the past century?

Answer 23

Improved crop varieties, increased use of fertilizers, pesticides, and irrigation

Question 24

In the U.S, how many hectares have we lost in the past 30 years?

Answer 24

140 million hectares