QUIZ # 10- ABE-1-MODULE 6

Question 1

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

Answer 1

Soil and water conservation (SWC)

Question 2

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

Answer 2

SWC technologies

Question 3

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

Answer 3

SWC approaches

Question 4

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)

Answer 4

Soil conservation practices

Question 5

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

Answer 5

SOIL EROSION

Question 6

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

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

Answer 6

“Erosion”

Question 7

most important agent of erosion in humid tropical areas

Answer 7

water

Question 8

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

Answer 8

wind

Question 9

important agent during landslides, mudflows and bankfalls

Answer 9

gravity (mass wasting)

Question 10

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

Answer 10

invisible

Question 11

Erosion arises from two types of problem:

Answer 11

◼ Geological problem
◼ Social and economic problem

Question 12

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

Answer 12

◼ Geological problem

Question 13

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

Answer 13

◼ Social and economic problem

Question 14

Erosion events are very _____________.

Answer 14

irregular

Question 15

Factors affecting Soil Erosion

Answer 15

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

Question 16

Soil erosion by water depends on:

Answer 16

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

Question 17

steep, sloping fields are more exposed to erosion;

Answer 17

slope:

Question 18

_____ soils are more sensitive to erosion

Answer 18

light

Question 19

_________ or ___________ flows induce more erosion

Answer 19

larger or rapid

Question 20

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

Answer 20

Erosion

Question 21

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 _____________.

Answer 21

reduced

Question 22

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

Answer 22

Newly irrigated

Question 23

Forms of Erosion by Water

Answer 23

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

Question 24

◼ 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.

Answer 24

Raindrop splash erosion

Question 25

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.

Answer 25

Sheet erosion

Question 26

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 _______________

Answer 26

sheet erosion

Question 27

◼ 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

Answer 27

Sheet erosion

Question 28

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

Answer 28

rill erosion

Question 29

◼ 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.

Answer 29

rill erosion

Question 30

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

Answer 30

Gully erosion

Question 31

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

Answer 31

gully erosion

Question 32

-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.

Answer 32

Stream channel erosion

Question 33

◼ 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.

Answer 33

Stream channel erosion

Question 34

Mechanics of Soil Erosion Process

Answer 34

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

Question 35

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

Answer 35

Soil detachment by rain fall

Question 36

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

Answer 36

Entrainment of Sediment

Question 37

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

Answer 37

3. Sediment Deposition

Question 38

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

Answer 38

SEDIMENTATION

Question 39

◼ 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

Answer 39

IMPORTANT FACTORS TO SOIL EROSION

Question 40

◼ 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

Answer 40

Universal Soil Loss Equation (USLE)

Question 41

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

Answer 41

The UNIVERSAL SOIL LOSS EQUATION

Question 42

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

Answer 42

The UNIVERSAL SOIL LOSS EQUATION

Question 43

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

Answer 43

The UNIVERSAL SOIL LOSS EQUATION

Question 44

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.

Answer 44

The UNIVERSAL SOIL LOSS EQUATION

Question 45

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

Answer 45

STANDARD EROSION PLOTS

Question 46

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.

Answer 46

Erosion Control Principles

Question 47

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

Answer 47

Three main principles

Question 48

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

Answer 48

stabilization

Question 49

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

Answer 49

Examples of stabilizing techniques

Question 50

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

Answer 50

Agronomic Measures

Question 51

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

Answer 51

Soil Management (Conservation Tillage)

Question 52

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

Answer 52

Mechanical Methods

Question 53

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

Answer 53

terrace

Question 54

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

Answer 54

Functions of a terrace

Question 55

TYPES OF A TERRACE

Answer 55

-BENCH -ZINGG -broad-based terrace

Question 56

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

Answer 56

BENCH

Question 57

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

Answer 57

BENCH

Question 58

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

Answer 58

ZINGG

Question 59

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

Answer 59

broad-based terrace

Question 60

◼ Terrace location ◼ Factors that influence terrace location (e.g. land slope, soil condition) Criteria for terrace location ◼ Minimum maintenance ◼ Ease of farming ◼ Erosion control

Answer 60

Planning the terrace system

Question 61

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.

Answer 61

Terrace Design