Tiếng anh chuên ngành thổ nhưỡng và môi trường đất ( unit 15 )

These changes can happen very easily, having profound effects on the soil and the landscape such as vegetation reduction, soil erosion, slope instability, increased flooding, and more se

Tiếng anh chuyên ngành Thổ nhưỡngvà Môi trường đất NXB Đại học quốc gia Hà Nội 2007 Tr 142 – 154 Tài liệu trong Thư viện điện tử ĐH Khoa học Tự nhiên có thể được sử dụng cho mục đích học tập và nghiên cứu cá nhân Nghiêm cấm mọi hình thức sao chép, in ấn phục vụ các mục đích khác nếu không được sự chấp thuận của nhà xuất bản và tác giả Mục lục Unit 15 Human impact on soils 2

A Reading 2

I Comprehension questions 3

II True-False sentences 4

I Comprehension questions 6

II True-False sentences 8

III Increasing your vocabulary 8

B WRITING 9

I Sentence-building 9

II Sentence - transforming 10

C FURTHER PRACTICE 11

Gap-filling 11

D TRANSLATION 12

I Translate into Vietnamese 12

II Translate into English 12

E Vocabulary 13

Unit 15. HUMAN IMPACT ON SOILS

Nguyễn Thị Minh Nguyệt

Unit 15

HUMAN IMPACT ON SOILS

• Warm-up Activities

- What are the good and the bad effects of human activities on soils?

-

part I

Soil is a great natural resource It is a combination of mineral and organic matter, structurally arranged in layers, and capable of supporting plant and animal life Soils cannot exist without plants, and plants are dependent on soils for support, air, water, and nutrients Soils are highly variable in nature This variation includes their structure, layering, color, range of particle sizes, chemistry, nutrients, acidity, temperature, water content, thickness, organic content, and its associated biota These properties vary because of differences in the parent material, climate, topography, organic content, and the amount of time it has had to develop Changes in one or more of these factors may drastically alter the soil properties, changing its nature and ability to support particular plant species These changes can happen very easily, having profound effects on the soil and the landscape such as vegetation reduction, soil erosion, slope instability, increased flooding, and more sediment in rivers The major changes induced by human activities include chemical changes (salinization and laterization), structural changes (compaction), hydrological changes, and soil erosion

There are many chemical changes within a soil which can be initiated by humans The most widespread and problematic are salinization and laterization

Salinization involves the accumulation of salts such as sodium chloride, potassium

chloride, calcium sulphate, and sodium carbonate within a soil This makes the soil alkaline, caustic, and generally restricts or inhibits plant growth Salinization may also lead to secondary problems such as soil erosion resulting from poor plant growth Salinization may occur naturally in semi-arid and arid areas where evapotranspiration or direct evaporation from the soil exceeds precipitation It may also occur in coastal regions which have saline groundwater

In areas where the evaporation of water from the soil is high, water is drawn upwards and evaporated from the soil surface Hence salts are left behind and are concentrated near the surface of the soil These results in a hard salty layer within the soil called a salt pan Salinization can be induced by irrigation and water abstraction

The abstraction of water leads to a rise in the groundwater table, driving salts towards the surface In coastal regions, withdrawal of underground freshwater, which floats on top of underground saline water (originating from the sea), pulls the saline water beneath it nearer to

the ground surface, contaminating the fresh water in the soil In addition, water in wells may become saline and therefore useless This is a particularly big problem in coastal regions such

as California and Israel, and islands such as Bahrain and Long Island, New York This was also a problem in cities such as London and Liverpool during the middle of the last century, until effective management of groundwater resources was introduced

Irrigation also enhances salinization by increasing the height of the water table in the immediate and adjacent areas over which irrigated water is spread This leads to the evaporation of water from within the soil, providing a process by which soil salts can be concentrated and drawn towards the ground surface With the rapid expansion of irrigation schemes in the last 20 years, the UN estimates that as much as 25 per cent of irrigated areas have become affected by salinization, making it a major land management problem For example, the percentage of soils affected and water logged amounts to 50 per cent of the irrigation areas in Iraq, 23 per cent in Pakistan, 30 per cent in Egypt, and 15 per cent in Iran

(Taken from "Environment Soil Biology" by Martin, W)

Answer the following questions

1 What is the two-sided dependence of soil and plants?

2 What does the variation of soil consist of?

3 What make the soil properties change? How do these changes occur?

4 Give examples of these changes' effects on soil and landscape

5 What are the most widespread and problematic chemical changes?

6 What does salinization involve? What makes the soil alkaline, caustic, and generally restricts or inhibits plants growth?

7 Where does salinization take place?

8 Where are salt left behind and concentrated near surface of the soil?

9 When there are a lot of salts in a soil layer, what do you call this phenomenon?

10 What is the big problem in coastal regions?

11 How does irrigation enhance salinization?

12 What does the UN estimate?

II True-False sentences

Decide whether the following statements are true "T", false "F" or there’s no information "N" according to the text Correct the false statements

1 There's an interaction between soil and plants

2 Changes to a soil structure can also have a profound effect on its properties

3 Because of having differences in the parent material, climate, topography,

organic content, and the amount of time it has had to develop, the soil properties change

4 Alteration in topography can not make the soil properties alter

5 Vegetation reduction and soil erosion are the most serious effects of changes of

soil properties on the soil

6 Human beings cause many chemical changes

7 Salinization takes place in coastal areas only

8 Salinization prevent plants from growing

9 The great impact on soil is caused by soil erosion

10 The soil in coastal areas with high evaporation of water from the soil is very

salty

11 In coastal regions, fresh water is not polluted and wells are not salty

12 London is the only city in the world suffering water problem for the last

decades

PART II

Laterization of the soil is a major problem in the tropics where soils are enriched in

aluminum and iron oxides These metal oxides accumulate due to strong tropical weathering Minerals in rocks are decomposed releasing metal ions into the soil water These are transported and concentrated by seasonal wetting and drying of the soil as layers of metal oxides Problems start to occur when these lateritic layers become exposes to air They become hard and inhibit plant growth leading to soil erosion and its associated problems Exposure of these layers may also be due to soil erosion, often as a result of deforestation In addition, deforestation may lead to increased evaporation of water from the soil, enhancing the process of laterization The extent to which laterization is a problem has not been fully assessed, but particular problem areas include northern India, the Cameroon, and central Africa Unfortunately, populations in these countries are heavily dependent on soil for subsistence agriculture and often degradation is difficult to reduce due to increasing pressures

of population growth on those lands

Changes to a soil structure - its mutual arrangement of grains - can also have a profound effect on properties These include the soil ability to retain water, to allow water to enter and flow through it, the strength of the soil, the degree to which the plant can penetrate it as well

as the withdrawal of water from it, and it resistance to erosion The main way soil structure can be altered is through the compaction, the pushing together of soil grain This may be done

by vehicles driving over its surface, overgrazing, trampling along public footpaths, or by ploughing, which compress the soil immediately below the ploughed surface

Compaction reduces the ability of a soil to retain water, to hold air, and to allow water to enter the soil and it increases its hardness This retards or inhibits plant growth and it may

enhance processes such as soil erosion by wind and water Soil compaction is a worldwide problem, but it is often greatest in developed countries where vehicles are common Soils are commonly ruined adjacent to building sites, and on old battlefields or military training areas where heavy vehicles are particularly common Unfortunately, compaction of soil is one of the hardest soil problems to remedy and it may take many decades before a soil can regain its original structure

Human also alters the chemistry of soil by the addition of organic or artificial fertilizers This may help increase the agricultural productivity, but it may also be detrimental to the soil, especially if the fertilizers are incorrectly applied This may lead to the deterioration of the soil, a reduction in vegetation, soil erosion and other associated phenomena

By far the greatest impact on the soil is caused by soil erosion This includes the abrasion

of water running over the surface, the breakup of soil due to the impact of raindrops, and the deflation of soil particles by the wind The various causal factors that may initiate soil erosion have already been discussed, such as deforestation, grazing, salinization, laterization, and compaction Many of these factors are inter-linked and should not be considered in isolation Bad farming techniques, urbanization, construction, mining, wars, and fires may also accelerate them Some of the worst affected areas are the result of a combination of these These areas include many of the coastal regions of the Mediterranean Sea, where fires and wars have led to vast areas of badlands Particularly, problematic are the consequences of soil erosion These include the increased likelihood of flooding, increased sediment loads often leading to silting up of reservoirs, and landsliding

Much can be done to try to retard soil erosion and conserve soil resources These include re-vegetation, crop management, slope run-off control, construction of gabions, and retaining walls and the dissemination of information regarding good land-use practices There is still, however, much to be achieved with regard to the correct use of one of the most valuable natural resources

(Taken from "Environment Soil Biology" by Martin,W.)

Answer the following questions

1 What is the main problem in the tropics? What are thesoils in the tropics enriched in?

2 What do the decomposed minerals in rocks release into the soil water? What may lead to increased evaporation of water from soils?

3 People in what countries depend on soil for substance agriculture heavily?

4 Why is it difficult to reduce soil degradation in these countries?

5 How do changes to a soil structure affect soil properties? What do these include?

6 What is soil compaction caused by? What effects does compaction have on soils?

7 How long does it take to regain soil original structure?

8 How do people change the chemistry of soils?

9 What are good and bad sides of the addition of organic and artificial fertilizers to soils?

10 What are the causal factors initiating soil erosion?

11 What should we do to retard soil erosion and conserve soil resources?

12 In your opinion, what have we done wrong with our soil resources?

Decide whether the following statements are true "T", false "F", or there’s no information given "N" according to the text Correct the false statements

1 Soil erosion is the most serious impact on the soil

2 If the fertilizers are used properly, agricultural productivity will be increased

3 Neither organic fertilizers nor artificial fertilizers have bad effects on soils

4 Careful monitoring and management of erosional and depositional processes

have to be undertaken to care for this environment

5 Before minerals in rocks are decomposed, they emit metal ions into the soil

water

6 When lateritic layers are exposed to air, they become hard and it is difficult to

grow plants on

7 Soil erosion is one of the crucial problems in the world today

8 Soil degradation in India, the Cameroon, and Central Africa is blamed on the

growth of human population

9 In developed countries soil compaction is not a problem because of the number

of vehicles in these countries

10 The pushing together of soil grains is called soil compaction

11 Rapid degradation of the forest soil accompanies deforestation

12 Compaction allows water to enter the soil and make the soil softer

Synonyms: Which words or phrases in part II have the same meaning as:

13 delay a progress

14 hasten

15 find access into

16 lying near

17 become worse

18 wearing away

19 link together

20 thrust out

B WRITING I Sentence-building Make necessary changes and additions to complete the following sentences from the prompts given below 1 It / be / clear / that / man / be / now / one / major factors / soil formation / development

2 Deforestation / the degradation / other vegetation, / particularly / near / margins / deserts / have caused / vegetated land / become barren / in / process / called / desertification

3 Many scientists / argue / desertification / have not / occur / as / result / human / activities

4 Organic soils / develop / mostly / plants / have / fall / stagnant water / where

decomposition / be / slow

5 Soil organic matter / be / a / very / active / important / portion / soil

6 Organic materials / be / decompose / microorganisms / particularly / bacteria / fungi

7 Today, human activity / may / play / role / soil / degradation / world

II Sentence - transforming

Change the following sentences from passive voice into active voice and vice versa

8 Our effects on soils are highlighted by catastrophic events

9 People have classified soils according to their texture

10 Carbonates may be found in all the particles-size classes of soil

11 Two of them are doing a research on soil formation

12 Agricultural management causes seasonal changes particularly in the topsoil through cultivation and fertilization