Chapter 4

Question 1

Adsorbed cations are also known as ____.

Answer 1

exchangeable cations

Question 2

What is the charge of agriculturally important soils?

Answer 2

negative charge

Question 3

The process whereby cations adsorbed on the surface of soil colloids is exchanged for those in the soil solution or in any medium that comes in contact with the soil colloids.

Answer 3

Cation exchange

Question 4

If nutrients are not absorbed by soil colloids, they are subject to what.

Answer 4

Loss through leaching

Question 5

Na-rich soils are in what state?

Answer 5

dispersed

Question 6

The element that is responsible in dispersing soil.

Answer 6

Na

Question 7

Ca-rich soils make the soil to be?

Answer 7

flocculated

Question 8

Element responsible in making flocculated soil

Answer 8

Ca

Question 9

Is dispersion a desirable characteristic of productive soil?

Answer 9

NOT desirable

Question 10

The CEC of permanent charge clays.

Answer 10

low CEC

Question 11

The buffering capacity of permanent charge clays?

Answer 11

low buffering capacity

Question 12

Accompanying ions

Answer 12

complementary ions

Question 13

What will happen to the ion of interest if the complementary ion is strongly adsorbed?

Answer 13

easily released

Question 14

The quantitative measure of the ability of soil to adsorb and exchange cations with those in the surrounding solution and with plant roots.

Answer 14

cation exchange capacity

Question 15

The sum of the negative charges of the soil.

Answer 15

cation exchange capacity

Question 16

The sum total of the exchangeable cations that a soil can adsorb.

Answer 16

cation exchange capacity

Question 17

The easily exchangeable cations.

Answer 17

electrostatically retained cations

Question 18

The cations that are readily available for plant uptake.

Answer 18

electrostatically retained cations

Question 19

The dissociation of H from OH- groups

Answer 19

deprotonation

Question 20

What will happen to the charge if there is deprotonation?

Answer 20

additional negative charge

Question 21

What is the CEC of OM?

Answer 21

100-300 cmolc/kg soil

Question 22

Tells us the degree to which the exchange sites are occupied by basic cations.

Answer 22

percentage base saturation

Question 23

Give examples of basic cations.

Answer 23

K
Ca
Mg
Na

Question 24

Give examples of acidic cations.

Answer 24

Al
H

Question 25

The atomic weight of Ca.

Answer 25

40 g/mol

Question 26

The atomic weight of Na.

Answer 26

23g/mol

Question 27

The atomic weight of K?

Answer 27

39g/mol

Question 28

The atomic weight of Mg.

Answer 28

24g/mol

Question 29

What will happen to the cations if there is high percentage cation saturation?

Answer 29

easily and rapidly released

Question 30

Enumerate the practical applications of CEC.

Answer 30

plant nutrition liming amelioration of Na affected soil environmental quality

Question 31

Enumerate the soil properties that determine CEC.

Answer 31

soil texture organic matter content nature of clay colloid pH percentage base saturation

Question 32

Enumerate the methods of determining CEC.

Answer 32

CEC determination at pH7 ammonium acetate:1N calculation of effective CEC CC determination using BaCl2

Question 33

Enumerate the soil processes that affect cation exchange.

Answer 33

weathering nutrient retention dispersion and flocculation buffering pH change

Question 34

The characteristics of cation exchange reactions

Answer 34

ER are stoichiometric and take place in equivalent amounts CE are instantaneous ER are reversible

Question 35

Factors affecting the extent of cation exchange.

Answer 35

1. Relative adsorbability of the cation on soil colloid or the relative replacing the power of the cation 2. Concentration of the solution 3. Nature of exchange materials 4. Geometric fit of ions into the mineral structure 5. Influence of complementary ions

Question 36

Between Kaolinite and Illite which has a rapid cation exchange?

Answer 36

Kaolinite

Question 37

Between kaolinite and illite which takes longer time?

Answer 37

illite

Question 38

High level of Ca is antagonistic to?

Answer 38

inhibit K

Question 39

High K would lead to

Answer 39

interfere Mg

Question 40

ESP stands for

Answer 40

Exchangeable Sodium Percentage

Question 41

Soils with high amounts of soluble sodium

Answer 41

Sodic soils