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2nd year > QUIZ # 10- ABE-1-MODULE 6 > Flashcards

QUIZ # 10- ABE-1-MODULE 6 Flashcards

1
Q

are those activities which maintain or enhance the productive capacity of the soil, water and vegetation in areas prone to degradation through
* prevention or reduction of soil erosion,
compaction, salinity;
* conservation or drainage of water and
* maintenance or improvement of soil fertility

A

Soil and water conservation (SWC)

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2
Q

are agronomic, vegetative, structural and management measures that control soil degradation and enhance productivity in the field

A

SWC technologies

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3
Q

are ways and means of support
that help to introduce, implement, adapt and apply SWC technologies in the field.

A

SWC approaches

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4
Q

are those farming operations and management strategies conducted
with the goal to control soil erosion by preventing or limiting soil particle detachment and transport in water or air (Baumhardt et al., 2014)

A

Soil conservation practices

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5
Q
  • the detachment of soil materials (gravel, sand, silt, and clay) and subsequent transport by an agent to an area of deposition
A

SOIL EROSION

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6
Q

comes from erodere, a Latin verb meaning “to gnaw”

___________ gnaws away at the earth like a dog at a bone

A

“Erosion”

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7
Q

most important agent of erosion in humid tropical areas

A

water

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8
Q

important agent in many parts of the world (in areas with arid climates)

A

wind

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9
Q

important agent during landslides, mudflows and bankfalls

A

gravity (mass wasting)

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10
Q

Over a short period, the process of erosion is almost ___________.

A

invisible

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11
Q

Erosion arises from two types of problem:

A

◼ Geological problem
◼ Social and economic problem

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12
Q

◼ weathering of surface layers of rock by water and biosphere
◼ Normal geologic erosion - 0.1 t/ha/yr

A

◼ Geological problem

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13
Q

◼ Urbanization and population growth
◼ Accelerated erosion - 10 to 700 t/ha/yr

A

◼ Social and economic problem

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14
Q

Erosion events are very _____________.

A

irregular

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15
Q

Factors affecting Soil Erosion

A
  1. Climate ( rainfall, wind )
  2. Soil erodibility
    ◼ Soil texture
    ◼ Soil structure
  3. Vegetation or plant cover
  4. Relief (Slope)
  5. Man’s activities
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16
Q

Soil erosion by water depends on:

A

(1) the slope
(2) the soil structure
(3) the volume or rate of flow of surface
runoff water

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17
Q

steep, sloping fields are more exposed to erosion;

A

slope:

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18
Q

_____ soils are more sensitive to erosion

A

light

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19
Q

_________ or ___________ flows induce more erosion

A

larger or rapid

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20
Q

usually heaviest during the early part
of irrigation, especially when irrigating on slopes.

A

Erosion

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21
Q

The dry surface soil, sometimes loosened by cultivation, is easily removed by flowing water. After the first irrigation, the soil is moist
and settles down, so erosion is _____________.

A

reduced

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22
Q

__________ areas are more sensitive to erosion, especially in their early stages.

A

Newly irrigated

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23
Q

Forms of Erosion by Water

A

◼ Raindrop splash erosion
◼ Sheet erosion
◼ Rill Erosion
◼ Gully erosion
◼ Stream channel erosion

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24
Q

◼ The first step in the erosion
process begins as raindrops
impact the soil surface.
◼ Raindrops typically fall with a
velocity of 20-30 feet per second.
The energy of these impacts are
sufficient to displace soil particles
as high as two feet vertically.
◼ The impact of a rainfall on a bare
soil can compact the upper layer of
soil, creating a hard crust that
inhibits plant establishment.

A

Raindrop splash erosion

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25
Q

is the even removal of a very thin layer or “sheet” of topsoil from sloping land.

occurs as runoff travels over disturbed ground, picking up and transporting
particles dislodged by splash erosion.

The process of _______________ is uniform, gradual and difficult to
detect until it develops into rill
erosion.

A

Sheet erosion

26
Q

The potential for _____________ is
dependent on the soil type,
velocity, and quantity of flow over
the surface. Long slopes, steep
slopes, and slopes that carry
higher volumes of runoff are
more susceptible to _______________

A

sheet erosion

27
Q

◼ only a thin layer of topsoil; or
the subsoil is partly exposed;
sometimes even parent rock
is exposed
◼ quite large amounts of coarse
sand, gravel and pebbles in
the arable layer, the finer
material has been removed
◼ exposure of the roots
◼ deposit of eroded material at
the foot of the slope

A

Sheet erosion

28
Q

occurs as runoff begins to form small
concentrated channels. As __________begins, erosion rates increase dramatically due to the resulting
concentrated higher velocity flows.

A

rill erosion

29
Q

◼ Construction sites that show signs of ________________ need to be re-evaluated and additional erosion control techniques employed. Rilling can be repaired by tilling and should be repaired as soon as possible in order to prevent gullies
from forming.

A

rill erosion

30
Q

is the removal of soil by a concentrated water
flow, large enough to form channels or gullies;

results from water moving in rills, which concentrate to form larger
channels (when rill erosion can
no longer be

must typically be repaired utilizing earthmoving equipment. _______________ can be prevented by quickly repairing rill erosion and
addressing the cause

A

Gully erosion

31
Q

The signs of _____________ on an irrigated field are:
◼ irregular changes in the shape and length of the furrows
◼ accumulation of eroded material at the bottom of the furrows
◼ exposure of plant roots

A

gully erosion

32
Q

-consists of both stream bed
and stream bank erosion.
◼ Stream bed erosion occurs as flows cut into the bottom of the channel, making it deeper and reaches a stable
slope. - The resulting slope is dependent on the channel materials, and flow properties.

A

Stream channel erosion

33
Q

◼ Stream bank erosion can also occur as soft materials are eroded from the stream bank or at bends in the channel. This type of stream bank erosion results in meandering waterways.
◼ One significant cause of both steam bed and stream bank
erosion is due to the increased frequency and duration of
runoff events that are a result of urban development.

A

Stream channel erosion

34
Q

Mechanics of Soil Erosion Process

A
  1. Soil detachment by rain fall
  2. Entrainment of Sediment
  3. Sediment Deposition
35
Q

process by which raindrops splash
sediment from the soil surface into the water of overland flow or runoff water.

A

Soil detachment by rain fall

36
Q

the process whereby overland flow
picks up sediments from the soil surface, whether in rills, between
rills and in sheet flow.

A

Entrainment of Sediment

37
Q

the process which is the result of sediment settling out under the action of gravity.

The rate depends on sediment size, being very rapid for coarse (sand) and very slow for fine ( silts and clay) particles, thus the silts and clays are transported and deposited farther away from where they

A
  1. Sediment Deposition
38
Q

occurs when eroded material that is being transported by water, settles out of the water column onto the surface, as the water flow slows

A

SEDIMENTATION

39
Q

◼ Kinetic energy
◼ Slope of the land
◼ Cover
◼ Resistance of the soil to detachment
and transport based on chemical and
physical properties of soil
◼ Conservation factors

A

IMPORTANT FACTORS TO SOIL EROSION

40
Q

◼ predicts the long term average annual rate of erosion on a field slope based on rainfall pattern, soil type, topography, crop system and management practices

A = R x K x LS x C x P

Threshold level of soil loss
- 8-12 tons/ha/yr
- 4 tons/ha/yr (thin topsoil)

Limitations:
can be used for splash erosion only
cannot be used in other country unless you modify R

A

Universal Soil Loss Equation (USLE)

41
Q

was developed using the English system of units. Its equivalent form in the metric unit system is presented by Kent Mitchell and Bubenzer (1981) as

E = 0.224 R K L S C P

where:
E = sheet erosion loss in kg/m2
R = rainfall erosivity factor
K = soil erodibility factor
L = slope length factor
S = slope gradient factor
C = cropping management factor
P = erosion control practice/conservation factor

A

The UNIVERSAL SOIL LOSS EQUATION

42
Q

has gained wide acceptance in the United States. It has recently been adapted by soil conservationists in many other countries.

A

The UNIVERSAL SOIL LOSS EQUATION

43
Q

was developed from agricultural plots with certain ranges of variations in soil, climatological and slope conditions.

A

The UNIVERSAL SOIL LOSS EQUATION

44
Q

Very simple to use, however, the validity of the _______ depends on how close the conditions to which it is
being applied at are to the range of conditions from which it was developed. It is best suited to small areas with low to moderately intense rainfall.

A

The UNIVERSAL SOIL LOSS EQUATION

45
Q

◼ 72.6 ft long
◼ 6 ft wide
◼ 9% slope
◼ Bare
◼ plowed up and down the slope
◼ no conservation measure

A

STANDARD EROSION PLOTS

46
Q

The control of soil erosion and
sedimentation needs to be based on the correct identification of source areas of sediment, a knowledge of the processes by which water and sediment are moved over the land surface, and an understanding of
how these processes are affected by the physical environment and socio-economic factors.

A

Erosion Control Principles

47
Q

◼ use land according to its capability
◼ protect the soil surface with some form of cover
◼ control runoff before it develops into an erosive force

A

Three main principles

48
Q

◼ The method used to prevent erosion from raindrop splash and sheet erosion is _____________.

A

stabilization

49
Q

-temporary and permanent vegetation
-mulching
-compost blankets
-erosion control products that absorb the impact of raindrops

A

Examples of stabilizing techniques

50
Q

Under erosion control practices

  1. Mulching
  2. Cover cropping
  3. Strip-cropping
  4. Crop Rotation
  5. Relay Cropping
  6. High Density Planting
  7. Multiple Cropping
  8. Alley Cropping (Sloping
    Agricultural Land Technology )
  9. Agroforestry
A

Agronomic Measures

51
Q

Under erosion control practices
1. Contouring
2. Minimum Tillage
3. Strip of Zone Tillage
(Precision Tillage)
4. Mulch Tillage
5. Subsoiling
6. Ridge-tying

A

Soil Management (Conservation Tillage)

52
Q

Soil Management (Conservation Tillage)
1. Terracing bench
Zingg or conservation bench terraces
broad-based
2. Grassed Waterways
3. Structures (Farm ponds and check dams)
4. Toward Soil Conservation – oriented Farming Systems

A

Mechanical Methods

53
Q

is an earth embankment or a ridge
and channel constructed across the slope at an acceptable grade.

A

terrace

54
Q
  1. reduce sheet and rill erosion
  2. prevent gully formation
  3. moisture conservation
  4. moderate flood or overland flows
A

Functions of a terrace

55
Q

TYPES OF A TERRACE

A

-BENCH
-ZINGG
-broad-based terrace

56
Q

e.g. Banaue Rice Terraces
➢ used for maximum moisture conservation
➢ used where land is at a premium
➢ conventional

A

BENCH

57
Q

e.g. Banaue Rice Terraces
➢ used for maximum moisture conservation
➢ used where land is at a premium
➢ conventional

A

BENCH

58
Q

◼ easier to farm than conventional
◼ used for maximum soil and water
conservation

A

ZINGG

59
Q

may either be graded or level.
◼ grade – fall in channel
◼ slope – fall in natural land surface

A

broad-based terrace

60
Q

◼ Terrace location
◼ Factors that influence terrace location (e.g. land slope, soil condition)

Criteria for terrace location
◼ Minimum maintenance
◼ Ease of farming
◼ Erosion control

A

Planning the terrace system

61
Q
  1. The allowable soil loss should be first estimated using relevant information on soil depth, fertility, land value, siltation damage downstream, etc.
  2. In the absence of soil loss information, the spacing may also
    be estimated from appropriate erosion equations such as the universal soil loss equation.
  3. No hard and fast rules can be laid down to follow in terrace layout because every field has its own individual problems.
  4. Good judgment and consideration of all factors are required to obtain the best possible layout terraces on each field.
A

Terrace Design

2nd year (13 decks)

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