Павлова Н.Ю. УП_АЯ_Ч1

2.Answer the questions:

1.What parts of plants derive energy from cell respiration?

2.What property is called soil aeration?

3.How is soil aeration reduced?

4.The term pH is used to measure only the acidity of any solution, isn’t it?

5.Do most plants (as well as animals) require pH acidic or alkaline?

6.What must all living cells contain to function properly?

3.Translate into English:

1.Корни получают энергию от клеточного дыхания.

2.Диффузия кислорода из атмосферы через почву называется аэрацией почвы.

3.Чтобы аэрация была достаточной, почва должна быть рыхлой и пористой.

4.Все живые клетки должны содержать определенное количество воды.

5.Растительные клетки получают воду через корни растений.

6.Но некоторые растения, такие как эпифиты, могут поглощать воду через свои листья.

7.Образование солей в почве делает невозможным для корней впитывать воду.

Soil Organisms, Humus, and Topsoil

The residue of organic matter that remains for a time after most of the feeding and digestion have occurred is called humus. Composting is the process of fostering the decay of organic wastes under more-or-less controlled conditions, and the resulting compost is the same as humus.

The activity of soil organisms integrates humus with mineral particles to create soil structure. For example, as earthworms feed on detritus, they ingest inorganic soil particles as well. As much as 15 tons per acre (37 tons per hectare) of soil may pass

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through earthworms each year. The sand, silt, and clay particles are bound together with humus into larger clumps and aggregates. The burrowing activity of organisms keeps the clumps loose. This loose, clumpy characteristic is referred to as soil structure.

Humus forms and soil structure develops mainly in the upper 4 to 12 inches (10 to 30 cm) of soil, the zone in which soil organisms are active. Thus, a layer of darkcolored soil with a clumpy, aggregate structure develops on of the lighter-colored, humus-poor, compacted soil. This layer of humus-rich soil is called topsoil; the soil below is subsoil. A careful cut through a natural, undisturbed soil reveals this layering, referred to as the soil profile.

Humus has phenomenal holding capacity for both water and nutrients, as much as 100-fold greater than clay on the basis of weight. The clumpy aggregate structure of topsoil greatly enhances infiltration, aeration, and workability. Regardless of soil texture, then, attributes are enhanced with humus and the soil structure it imparts. Sandy soils may be given significant water-holding capacity, clayey soils may be given sufficient aeration and infiltration, and loamy and silty soils may be enhanced in all regards.

A productive soil must be recognized as the entirety of a dynamic system of mineral particles, detritus, and soil organisms all interacting together in a way that optimizes all the attributes that support plant productivity. An important point to remember is that the system is dynamic. Although resistant to digestion, humus does decompose at the rate of about 20 to 50 percent of its volume per year, depending on conditions. Consequently, without additions of sufficient detritus, soil organisms starve, humus content declines, and there is a loss of soil structure. This loss of humus and the consequent collapse of topsoil is called mineralization because what is left is just the gritty mineral content – sand, silt, and clay – devoid of humus. Topsoil is formed and maintained only through continual additions of detritus.

Growth of plants, whether grasses or forests, provides a continuous source of detritus which supports soil organisms. In turn, soil organisms support the growth of

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1.What is called humus?

2.Which activity creates soil structure?

3.How much soil may pass through earthworms each year?

4.Where do humus and soil structure develop?

5.Is humus-rich or humus-poor soil called topsoil?

6.How do we call the soil below topsoil?

7.Why is the loss of humus and the consequent collapse of topsoil called mineralization?

8.Does a vegetation cover or soil organisms protect the soil form erosion?

3.Translate into English:

1.Деятельность почвенных организмов объединяет гумус с минеральными частицами, чтобы создать почвенную структуру.

2.Гумус образуется и почвенная структура развивается в верхней зоне (10-30

см), где почвенные организмы активны.

3. Этот слой богатой гумусом почвы называется верхним слоем. 4.Почва ниже верхнего слоя называется подпочвой.

5.Срез через естественную ненарушенную почву называется почвенным профилем.

6.Гумус имеет удивительную способность удерживать как воду, так и питательные вещества.

7.Необходимо помнить, что почвенная система является динамичной.

8.Потеря гумуса и разрушение верхнего слоя почвы называется минерализацией.

9.Верхний слой почвы формируется и сохраняется только через непрерывное добавление детритов.

10.Растительный покров защищает почву от эрозии.

Speaking Activities

1. Use the information from additional texts to speak about:

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1.Weathering

2.Leaching

3.Soil’s nutrient-holding capacity

4.Organic and inorganic fertilizers

5.Soil’s water-holding capacity

6.Soil aeration

7.Humus

2.Roleplay. Choose one of the following situations to act out:

1.Two young researches are discussing the results of their experiments on testing different effects of soil texture on infiltration, aeration, water-holding capacity and nutrient-holding capacity.

2.Two students are discussing the relationships between soil texture and its various properties with their lecturer. They are asking him some questions.

3.A group of students is asking their instructor about processes of weathering and leaching. They are especially interested in problems of pollution resulting from leaching.

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Unit 2

PRACTICES LEADING TO BARE SOIL AND EROSION

Vocabulary Practice

1. Divide the words and expressions given below into two lists:”protectors

of the soil” and “threats to the soil”:

vegetation; topsoil; removal; clumpy soil; well-anchored grass; loose topsoil; litter mat; vegetative cover; dislodged particles; erosion; erosion control; grass; gully; humus; desertification; raindrop

2. Match word combinations with their translations:

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7.The finer particles of …, …, and … are carried away by runoff or wind.

8.As erosion removes the finer materials, the remaining soil becomes coarser - …, …, and rocky.

9.Soil that is left unprotected erodes as a result of the action of … and ….

5.Translate into English:

1.С хорошей инфильтрацией сток минимальный.

2.Трава особенно хороша для борьбы с эрозией.

3.Растительность уменьшает скорость ветра и удерживает почвенные частицы.

4.Почва сильно подвержена эрозии, когда она голая и незащищѐнная

5.Разрушительной особенностью эрозии является дифференцированное вымывание почвенных частиц.

6.Эрозия вымывает тонкие материалы, более легкие частицы глины и ила.

7.Эрозия также сильно снижает водоудерживающую способность почвы.

8.Глина и гумус являются самыми важными компонентами способности почвы удерживать питательные вещества.

Bare Soil and Erosion

Read and translate the text. There are four parts in it. While reading it Match a heading to each one:

Water-holding and nutrient-holding capacity of soils.

Removal of soil particles.

Results of water and wind erosion.

Devastating feature of erosion.

1. Most destructive to soil is erosion, the process of soil particles being picked up and carried away by water or wind. The removal may be slow and subtle as soil is gradually blown away by wind, or it may be dramatic as gullies are washed out in a single storm.

In natural terrestrial ecosystems other than deserts, a vegetative cover protects against erosion. The energy of falling raindrops is dissipated against the vegetation,

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and the water infiltrates gently into the loose topsoil without disturbing its structure. With good infiltration, runoff is minimal. Any runoff that does occur is slowed as the water moves through the vegetative or litter mat, and so the water does not have sufficient energy to pick up soil particles. Grass is particularly good for erosion control because when runoff volume and velocity increase, well-anchored grass simply lies down, making a smooth mat over which the water can flow without disturbing the soil underneath. Similarly, vegetation slows the velocity of wind and holds soil particles.

2.When soil is left bare and unprotected, however, it is highly subject to erosion. Water erosion starts as the impact of falling raindrops breaks up the clumpy structure of topsoil. The dislodged particles wash into spaces between other aggregates, clogging the spaces and thereby decreasing infiltration and aeration. The decreased infiltration results in more water running off the surface, causing further stages of erosion.

As further runoff occurs, the water converges into rivulets and streams, which have greater volume, velocity, and energy and hence greater capacity to pick up and remove soil particles.

A very important and devastating feature of erosion is that it always involves the differential removal of soil particles. This is true of both wind and water erosion. The lighter particles of humus and clay are the first to go, while rocks, stones, and coarse sand remain behind. Consequently, as erosion removes the finer materials, the remaining soil becomes progressively coarser – sandy, stony, and rocky. Such coarse soils are frequently a reflection of past or ongoing erosion. Did you ever wonder why deserts are full of sand? The sand is what remains; the finer, lighter clay and silt particles have been blown away.

3.Recall that clay and humus are the most important components for nutrientholding capacity. As these components are removed, most of the nutrients are removed as well because they are bound to these particles. Then waterways receiving these materials may get an oversupply of nutrients.