Chapter 3 soil science

Question 1

The majority of the fine, absorbing roots of a tree are in the _____ and _____ horizons.

Answer 1

O, A

Question 2

Driving vehicles across wet soil will ________ the soil and destroy soil ________ _________

Answer 2

Compact, pore space

Question 3

__________ _________ is the soil property that resists changes to the ph.

Answer 3

Buffering capacity

Question 4

True/false-negatively charged clay particles hold cations near their surface

Answer 4

True

Question 5

5. In 1 ft of clay soil with 4 inches of water in the soil, approximately how many inches of water would be available to the tree?

Answer 5

1 in

Question 6

________ ________ modifies the effects of soil texture as the soil particles form clumps or aggregates

Answer 6

Soil structure

Question 7

7. True/false-soil can hold water so tightly in micropores that the ability of tree roots to absorb the water is restricted.

Answer 7

True

Question 8

On the ph scale, less than 7 is _________, 7 is __________ and more than 7 is __________.

Answer 8

Acidic, neutral, alkaline

Question 9

True/false-over time, mulching can improve soil structure, reduce compaction, and add organic matter to the soil.

Answer 9

True

Question 10

A ph of 5 is ______times more acidic than a ph of 7.

Answer 10

100

Question 11

12. The process in which ions of essential elements wash down through the soil profile and are lost is called

Answer 11

Leaching

Question 12

13. Many essential elements are dissolved in soil water in the form of positively charged particles called

Answer 12

Cations

Question 13

14. If the soil is too _________, iron and manganese may be in a chemical form that is unavailable to trees.

Answer 13

Alkaline

Question 14

15. The buffering capacity is the resistance of a soil to changes in ph. Clay soils and soils high in organic matter usually have a _______ buffering capacity

Answer 14

High

Question 15

16. The ________is the zone of intense biological activity near the actively elongating roots.

Answer 15

Rhizosphere

Question 16

17. The diversity of organisms living, moving and interacting in the soil is often referred to as the _____ ______ ______.

Answer 16

Soil food web

Question 17

18. Water that drains from the macropores is called ________ water. Following drainage, the soil is said to be at _________ ________.

Answer 17

Gravitational, field capacity

Question 18

19. True/false-most soil organisms cause disease or decay in tree roots.

Answer 18

False

Question 19

Field capacity

Answer 19

Maximum soil moisture content following the drainage of water due to the force of gravity

Question 20

CEC-cation exchange capacity

Answer 20

Ability of a soil to adsorb and hold cations. Measures soil fertility, clay composition, engineering characteristics.

Question 21

Cations

Answer 21

Positively charged ion.

Question 22

Horizons

Answer 22

Soil profile o,e,a,b,c

O-Organic layer,
A-absorbing roots and inorganic material
B-mix of surface material and parent material
C-weathered parent materia

Question 23

Aggregate

Answer 23

Cluster or mix of small particles of soil of differ sizes that are bonded.

Question 24

Bulk density

Answer 24

Mass of dried soil per unit of undisturbed soil volume.

Question 24

T/f soils with high percentage of fine particles are easily compacted.

Answer 24

True

Question 25

In acidic soils

Answer 25

Phosphorus maybe not available and other elements (copper and manganese) may become toxic.

Question 26

In alkaline soils

Answer 26

Iron, zinc and manganese are unavailable but calcium, magnesium and potassium are available

Question 27

What do you add to raise the soils ph

Answer 27

Lime

Question 28

To lower the ph, add

Answer 28

Sulfur

Question 29

T/f organic matter and clay have a high negative charge density

Answer 29

True

Question 30

Sodic soil

Answer 30

Soils in which cation sodium occupies an unusually high percentage of Cec.

Question 31

Mineralization

Answer 31

Organic bound plant nutrients are converted into inorganic plant available forms.

Question 32

Capillary water

Answer 32

Water that remains is held in micro pores

Question 33

Teacup effect

Answer 33

If plant is planted in clay soil and backfilled with coarser soil, bowl will retain too much water.

Question 34

Structural soils

Answer 34

Designed soils that can be compacted to meet engineering requirements and still allow root growth and development.

Question 35

Actinomycetes

Answer 35

Type of bacteria that is symbiotic with some species and helps decompose organic matter to form hummus.