Soils vary in their content of clay very fine particles, silt fine particles, sand medium-size particles, and gravel coarse to very coarse particles.. Soils containing a mixture of clay,
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Tiếng anh chuyên ngành Thổ nhưỡngvà Môi trường đất NXB Đại học quốc gia Hà Nội 2007 Tr 92 – 100 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 10 Soil texture, porosity, acidity 2
A Reading 2
I Comprehension questions 3
II True-false questions 4
III Increasing your vocabulary 4
B Writing 5
C Further practice 6
D Translation 8
I Translate into Vietnamese 8
II Translate into English 8
E Vocabulary 9
Unit 10 Soil texture, porosity, acidity
Nguyễn Thị Minh Nguyệt
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Soil texture, porosity, acidity
• Warm-up activities
- Name the soils and their characteristics that you know
- Which soil is best for growing most crops?
Soils vary in their content of clay (very fine particles), silt (fine particles), sand (medium-size particles), and gravel (coarse to very coarse particles) The relative amounts
of the different sizes and types of mineral particles determine soil texture Soils containing
a mixture of clay, sand silt and humus are called loams
To get an idea of a soil's texture, take a small amount of topsoil, moisten it, and rub it between your fingers and thumb A gritty feel means that it contains a lot of sand A sticky feel means a high clay content, and you should be able to roll it into a clump Silt-laden soil feels smooth like flour A loam topsoil, best suited for plant growth, has a texture between these extremes-a crumbly, spongy feeling with many of its particles clumped loosely together
Soil texture helps determine soil porosity: a measure of the volume of pores or spaces per volume of soil and average distances between those spaces A porous soil (with many pores) can hold water and air than a less porous soil The average size of the spaces or pores in a soil determines soil permeability: the rate at which water and air move from upper to lower soil layers Soil porosity is also influenced by soil structure: how soil particles are organized and clumped together
Loams are the best soils for growing most crops because they hold lots of water but not too tightly for plant roots to absorb Sandy soils are easy to work, but water flows rapidly through them They are useful for growing irrigated crops or those with low water requirements, such as peanuts and strawberries
The particles in clay soils are very small and easily compacted When these soils get wet, they form large, dense clumps, explaining why wet clay can be molded into bricks and pottery Clay soils are more porous and have a greater water-holding capacity than sandy soils, but the pore spaces are so small that these soils have a low permeability Because little water can infiltrate to lower levels, the upper layers can easily become too waterlogged for most crops
Acidity and basicity of substances in water solution are commonly expressed in terms
of pH Soils vary in acidity, and the pH of a soil influences uptake of soil nutrients by plants Plants vary in the pH ranges they can tolerate
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Answer the following questions
1 How do soils vary? How can we give a concept of soil's texture?
2 Which soils are loams ? Why are they the best for growing crops?
3 Why can we roll soil with a high clay content?
4 Why does a porous soil hold more water and air than a less porous soil?
5 What does soil permeability mean? What can determine it?
6 Why can people mould wet clay into bricks and pottery?
7 What are characteristics of the particles in clay soil?
8 Are sandy soils useful for growing peanuts and strawberries?
9 What does the soil structure have influence on?
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10 Why are the upper layers easy to become waterlogged for crops?
Decide whether the following statements are true "T" or false "F" Correct the false statements
1 The relative amounts of the different sizes and types of mineral particles
determine loams
2 People have to depend on clay, silt, gravel and sand content to group soil into
textual classes
3 Loams are soils, which contain a mixture of clay, sand, silt, and humus
4 It's difficult to get an idea of soil composition
5 A less porous soil can hold less water than a porous soil
6 There are not many pores in porous soil
7 Sandy soil is good for growing peanuts and strawberries
8 Bricks and pottery are made from wet clay
9 Clay soils and sandy soils have the same water-holding capacity
10 The pore spaces of clay soils are very small
Complete the following statements with the appreciate words given below:
sand water and air mineral particles gravel wet clay sandy soil loams clay content soil texture
11 Soils containing a mixture of a clay, sand silt and humus are called (1)
12 Bricks and pottery are made from (2)
13 A porous soil (with many pores) can hold (3) than a less porous soil
14 (4) are easy to work, but water flows rapidly through them
15 A gritty feel means that it contains a lot of (5)
16 A sticky feel means a high (6)
17 The relative amounts of the different size and of (7) determine
Trang 518 Soils vary in their content of clay, silt, sand and (9)
Sentence-transforming
Finish each of the following sentences in such a way that it means the same as the sentence printed before it
1 Soil containing a mixture of clay, sand, silt and humus are called loams
Loams are soils which
2 A porous soil can hold more water and air than a less porous soil
A less porous soil
3 Loams are the best soils for growing most crops because they hold lots of water but not too tightly for plant roots to absorb
As
4 It is useful for growing irrigated crops in sandy soils
Sandy soils
5 People can mold wet clay into bricks and pottery
Brick and pottery
6 Clay soils have a greater water-holding capacity than sandy soils
Sandy soils
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C Further practice
Exercise 1: Expression of degree
Look at the following pairs of sentences Notice that the first half of each sentence describes a state and the second half expresses a consequence
Example: The soil was dry so the seed could not germinate
The soil was heavy and clayey and , as a result, it was unsuitable for root crops
We can express these sentences in another way using the expression of degree too:
Example: The soil was too dry for the seed to germinate
The soil was too heavy and clayey to be suitable for root crops
Rewrite the following sentences using too as in example (c) and (d) above and make any other changes that are necessary
7 The soil particles are fine so the water cannot percolate easily through the soil
8 Because the soil was compact, it was not suitable for root crops
9 Soil aeration was inadequate and consequently the plant could not receive a proper supply of oxygen
10 As a result of the land being waterlogged, it was not possible to produce a healthy crop
11 The soil profile was so shallow that it could not give the roots sufficient anchorage
12 As the root system was poorly developed, the plant could not produce a good top growth
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14 The current was so swift that the silt would not be deposited
Now look at the sentences you have written and rewrite them using not + adjective + enough, using the adjective given for each sentence
Example: The soil was too dry for the seed to germinate (wet)
= The soil was not wet enough for the seed to germinate
The soil was too heavy and clayey to be suitable for root crops (light and sandy)
= The soil was not light and sandy enough to be suitable for root crops
1 The soil particles are fine so the water cannot percolate easily through the soil
(coarse)
2 Because the soil was compact, it was not suitable for root crops
(loose)
3 Soil aeration was inadequate and consequently the plant could not receive a proper supply of oxygen
(adaquate)
4 As a result of the land being waterlogged, it was not possible to produce a healthy crop
(well-drained)
5 The soil profile was so shallow that it could not give the roots sufficient anchorage (deep)
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6 As the root system was poorly developed, the plant could not produce a good top growth
(well-developed)
7 It was dark as a result photosynthesis could not take place
(bright)
8 The current was so swift that the silt would not be deposited
(slow)
The soil is always an important component in the system comprising the lithosphere, the atmosphere and the biosphere Soil particles reflect the varying nature of the interactions with this system Soil is very essential for many human activities, and we can only successfully and sustainably undertake these activities if we understand how soil has been developed and how it is affected by changes in the system, particularly those in the biosphere caused by our manipulation of vegetation and soil
(Taken from "Environmental Sciences" by Wilson, R.)
1 ánh sáng mặt trời cung cấp năng lượng cho quá trình chuyển nước từ đất và cacbon điôxít từ không khí thành đường và hyđrát cacbon
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3 Nếu đất quá lạnh thì sự nảy mầm của cây cối không thể xảy ra
4 Thành phần cơ giới là đặc tính quan trọng của đất bởi vì ở một phạm vi nào đó nó sẽ quyết định tỷ lệ hút nước, sự tích trữ nước ở trong đất, tính thấm khí và nó sẽ ảnh hưởng đến độ phì nhiêu của đất Ví dụ, đất cát thô rất dễ canh tác, có tính thấm khí tốt cho sự phát triển của rễ và dễ làm ướt, nhưng loại đất này cũng khô rất nhanh và dễ bị mất các chất dinh dưỡng cho cây trồng Còn các loại đất sét lại rất khó làm ướt, khó canh tác và cũng khó tháo rút nước
1 absorb (v) : hấp thụ, ngấm
2 brick (n) : gạch
3 clay (n) : đất sét
4 clump (v) : tạo thành lùm, thành đống
5 coarse (adj) : thô, không mịn
6 compact (adj) : nén, rắn chắc
7 content (n) : hàm lượng
8 dense (adj) : dày đặc, chặt
9 grit (n) : hạt cát, hạt sỏi
10 infiltrate (v) : xâm nhập
11 irrigate (v) : tưới nước
12 loam (n) : đất giàu mùn, đất thịt
13 moisten (v) : làm ẩm
Trang 1014 mold (v) : đúc theo khuôn
15 permeable (adj) : dễ them
16 porous (adj) : lỗ rỗng, tính rỗng
17 pottery (n) : đồ gốm
18 roll (v) : cuộn tròn, vo viên
19 rub (v) : chà xát
20 sticky (adj) : dẻo, dính
21 spongy (adj) : mềm, xốp, đàn hồi
22 tolerate (v) : chịu đựng
23 volume (n) : khối lượng
24 waterlogged (adj) : ngập úng