Problem Soils

Question 1

Types of problem soils

Answer 1

1. Acid soils
2. Calcareous soils
3. Salt affected soil

Question 2

one of the most important soil
fertility problems in the tropics

Answer 2

Acid soils

Question 3

Soils become acidic when considerable portions of
the exchangeable cations are

Answer 3

hydrogen (H+) and
Al3+

Question 4

acidic cations-

Answer 4

Fe, Al, H

Question 5

basic cations-

Answer 5

Ca, Mg, Na, K

Question 6

produced from soil organic matter
decomposition

Answer 6

Organic acids

Question 7

Strong acids?

Answer 7

c. carboxylic acid
d. phenolic acid

Question 8

organic matter forms Soluble complexes with
non-acid nutrient cations (Ca & Mg) thus,
facilitating the loss of these cations by_____.

Answer 8

Leaching

Question 9

removal
of H+ ions from
functional group of
organic matter.

Answer 9

Deprotonation

Question 10

rain water or irrigation water that moves
downward through the soil dissolves nutrients
and move with water

Answer 10

Leaching

Question 11

soils that developed from_____
are likely to be more acidic than those
developed from shale or limestone

Answer 11

Weathered granite

Question 12

H+ and Al3+ in the soil solution

Answer 12

Active acidity

Question 13

portion of H+ and Al3+ ions
that are adsorbed by soil colloids (e.g., clay and
organic matter) that can be replaced by salt
solution such as KCl or NaCl.

Answer 13

Exchangeable acidity

Question 14

refers to bound H+ and Al3+ ions
that cannot be replaced by salt solution.

Answer 14

Residual acidity

Question 15

sulfur oxidation in acid sulfate
soil

Answer 15

Potential acidity-

Question 16

can form soluble complexes with
Al ions that are non-toxic to plants and microbes.

Answer 16

organic acids

Question 17

contains oxides of Ca, Mg and K)

Answer 17

Wood ashes

Question 18

Managing acid soil

Answer 18

2. Using organic matter
3. Wood ashes (contains oxides of Ca, Mg and K)
4. Biochar

Question 19

A Soil with high calcium carbonate (CaCO3)
content and give effervescence visibly releasing
CO2 gas treated with hydrochloric acid (HCl)

Answer 19

Calcareous soils

Question 20

• CaCO3 content ranged from___%to___%
by weight

Answer 20

3% to more than 25%

Question 21

pH value of Calcareous soils

Answer 21

7.6-8.3

Question 22

Why calcareous soils have
alkaline pH

Answer 22

Dissolution of CaCo3 in water produces OH- which
raises soil pH

Question 23

• Formed largely by the weathering of parent
material rich in CaCO3 such limestone, chalk, marl

Answer 23

calcareous soils

Question 24

Commonly found in arid and semi-arid region
(evapotranspiration>precipitation)

Answer 24

calcareous soils

Question 25

True or false • Application of acid forming fertilizers such as ammonium sulfate and urea fertilizers can manage calcareous soils

Answer 25

True

Question 26

Problems associated with calcareous soils

Answer 26

1. Crust formation 2. Ammonia volatilization 3. Precipitation of soluble phosphate 4. Precipitation of iron compounds

Question 27

• White alkali salts • Salty white crusts on the soil surface due to accumulation and precipitation of CaSO4, CaCO3 and MgCO3, CaCl2 , MgSO4, MgCl2, NaC

Answer 27

Saline soils

Question 28

pH of saline soils

Answer 28

pH < 8.5

Question 29

Effect on plant growth? ELECTRICAL CONDUCTIVITY: 8.1 to 16 , Strongly saline

Answer 29

Most cultivated plants are inhibited

Question 30

1 mmhos/cm=?

Answer 30

100 S/m

Question 31

1 Siemens/cm= ?

Answer 31

1 mmhos/cm

Question 32

Is <640 ppm salt suitable for crops?

Answer 32

Uu hehe

Question 33

TRUE OR FALSE >1,600 ppm salt is suitable for crops

Answer 33

false

Question 34

How do salts accumulate in soils?

Answer 34

1. Weathering of primary minerals 2. High evaporation, low precipitation 3. Irrigation water containing high levels of salts 4. Application of fertilizers, amendments and manure containing high salts

Question 35

The following are effects of saline soils on plant. EXCEPT 1. Wilting 2. Root injury 3. Poor germination 4.Leaf burn 5. Stunted growth 6. Death 7. None of the above

Answer 35

7. None of the above

Question 36

• Black alkali soils • EC < 4 dSm-1 • Exchangeable Na (>15 %)

Answer 36

Sodic soils

Question 37

Ph of sodic soils

Answer 37

pH at or above 8.5

Question 38

True or false Sodic soils are dispersed soil condition

Answer 38

True

Question 39

1. Dispersion of soil colloids leads to development of compact soils. true or false?

Answer 39

True

Question 40

White crust on the surface formed from dispersed organic matter is a symptoms of sodic soil. True or false

Answer 40

False- BLACK CRUST

Question 41

Soil particles will disperse if concentrations of (Ca2+ + Mg+) are INCREASED relative to the concentration o f Na* (SAR i s increased). T or F?

Answer 41

False- DECREASED

Question 42

• EC > 4 dSm-1 • Exchangeable Na is greater than 15 % • pH less than 8.5 • Contains large amount of total soluble salts • Good soil physical properties as long as an excess of soluble salts is present

Answer 42

Saline-sodic soils

Question 43

Saline sodic pH?

Answer 43

pH less than 8.5

Question 44

. Applying irrigation (flooding) approximately 1 foot high can reclaim saline soils T or f?

Answer 44

T

Question 45

• 6 inches or 15.24 cm can remove___% of salt within the topsoil (1,524,000 million L ha-1)

Answer 45

50%

Question 46

12 inches or 30.48 cm can remove__ % of salt within the topsoil (3,048,000 million L ha-1)

Answer 46

80%

Question 47

24 inches or 60.96 cm can remove70 % of salt within the topsoil (6,096,000 million L ha-1) T or f

Answer 47

F - 90%

Question 48

Ngano deman ko niya ge pursue

Answer 48

Its because i dasurv betterrrr😝😝😝🫵🫵🫵🫵

Question 49

Symptoms: 1. Wilting 2. Root injury 3. Poor germination 4. Leaf burn 5. Stunted growth 6. Death The following symptoms above are the effects of ___ soils on plants a. Sodic soil B. Saline-sodic soils C. Calcareous soils D. Saline soils

Answer 49

D. Saline soils