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Soils > Problem Soils > Flashcards

Problem Soils Flashcards

1
Q

Types of problem soils

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

one of the most important soil
fertility problems in the tropics

A

Acid soils

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3
Q

Soils become acidic when considerable portions of
the exchangeable cations are

A

hydrogen (H+) and
Al3+

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4
Q

acidic cations-

A

Fe, Al, H

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5
Q

basic cations-

A

Ca, Mg, Na, K

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6
Q

produced from soil organic matter
decomposition

A

Organic acids

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7
Q

Strong acids?

A

c. carboxylic acid
d. phenolic acid

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8
Q

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

A

Leaching

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9
Q

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

A

Deprotonation

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10
Q

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

A

Leaching

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11
Q

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

A

Weathered granite

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12
Q

H+ and Al3+ in the soil solution

A

Active acidity

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13
Q

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.

A

Exchangeable acidity

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14
Q

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

A

Residual acidity

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15
Q

sulfur oxidation in acid sulfate
soil

A

Potential acidity-

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16
Q

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

A

organic acids

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17
Q

contains oxides of Ca, Mg and K)

A

Wood ashes

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18
Q

Managing acid soil

A
  1. Using organic matter
  2. Wood ashes (contains oxides of Ca, Mg and K)
  3. Biochar
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19
Q

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

A

Calcareous soils

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20
Q

• CaCO3 content ranged from___%to___%
by weight

A

3% to more than 25%

21
Q

pH value of Calcareous soils

A

7.6-8.3

22
Q

Why calcareous soils have
alkaline pH

A

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

23
Q

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

A

calcareous soils

24
Q

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

A

calcareous soils

25
Q

True or false

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

A

True

26
Q

Problems associated with
calcareous soils

A
  1. Crust formation
  2. Ammonia volatilization
  3. Precipitation of soluble phosphate
  4. Precipitation of iron compounds
27
Q

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

A

Saline soils

28
Q

pH of saline soils

A

pH < 8.5

29
Q

Effect on plant growth?

ELECTRICAL CONDUCTIVITY: 8.1 to 16 , Strongly saline

A

Most cultivated plants are
inhibited

30
Q

1 mmhos/cm=?

A

100 S/m

31
Q

1 Siemens/cm= ?

A

1 mmhos/cm

32
Q

Is <640 ppm salt suitable for crops?

A

Uu hehe

33
Q

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

A

false

34
Q

How do salts accumulate in soils?

A
  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
35
Q

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

A
  1. None of the above
36
Q

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

A

Sodic soils

37
Q

Ph of sodic soils

A

pH at or above 8.5

38
Q

True or false

Sodic soils are dispersed soil condition

A

True

39
Q
  1. Dispersion of soil colloids leads to development
    of compact soils. true or false?
A

True

40
Q

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

A

False- BLACK CRUST

41
Q

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?

A

False- DECREASED

42
Q

• 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

A

Saline-sodic soils

43
Q

Saline sodic pH?

A

pH less than 8.5

44
Q

. Applying irrigation (flooding) approximately 1 foot
high can reclaim saline soils

T or f?

A

T

45
Q

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

A

50%

46
Q

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

A

80%

47
Q

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

T or f

A

F - 90%

48
Q

Ngano deman ko niya ge pursue

A

Its because i dasurv betterrrr😝😝😝🫵🫵🫵🫵

49
Q

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

A

D. Saline soils

Soils (4 decks)

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