Unit 10

Read the text and do the tasks.

METHODS OF IRRIGATION (PART 2)

Sprinkler or spray irrigation applies water to the surface of the soil in the form of a spray, and is a form of artificial rain. A common type of sprinkler head is the revolving one, which distributes water radially. This form of irrigation has advantages over other surface irrigation. It can be adapted for use on almost all types of soil, especially sandy soils which absorb water rapidly. It enables erosion to be controlled on steep land and can often be used on soils that are too shallow, too steep or too rolling to be irrigated by surface methods. Small streams of water can be used efficiently with this method, and it is adaptable to all the major crops with the exception of those, like rice, that require standing water. A uniform application of water is made possible, and the amount arid timing of the irrigation can be easily controlled. Land is not needed for irrigation structures, and so larger areas are available for cropping.

There are, however, a number of disadvantages of sprinkler systems. The water distribution is easily affected by the wind, which may disturb the pattern of wetting so that some parts get too much water and some too little. The power requirements necessary to maintain the water pressure are usually greater than for other methods of irrigation, and the water used must be clean and free from debris. To ensure the most economical use of the equipment, a constant supply of water is needed. Most important of all, the initial costs of installing such systems are very high. It is especially popular as a form of supplemental irrigation in areas with adequate rainfall, as it requires the least alternation of normal techniques of cultivation.

Subirrigation or subsoil irrigation applies water beneath the ground rather than on the surface. By means of lateral ditches or mole or tile drains, a water-table is maintained at some predetermined depth below the soil surface. From the water-table the water seeps upwards to the plant roots through capillary action. This method of irrigation requires complete control of the elevation of the water-table to ensure that the plant root zone in the soil is kept free from excess water.

Lands suitable for this method of irrigation are rather limited, since it requires a special combination of natural conditions. It needs a layer of permeable soil immediately below the surface to allow the free movement of water, and a level surface which should be approximately parallel to the water-table.

TASKS

1. Translate the following words into. Be sure of their pronunciation.

1. to apply, to distribute, to adapt, to enable, to require, to be affected, to disturb, to maintain, to install, to seep, to keep, to limit, to need, to allow.

2. artificial, common, sandy, shallow, steep, rolling, adaptable, major, possible, arid, available, economical, constant, important, initial, supplemental, adequate, lateral, complete, suitable, natural, permeable.

3. sprinkler, surface, use, erosion, the exception, application, the amount, disadvantages, distribution, requirements, debris, the equipment, a supply, costs, alternation, techniques, cultivation, mole, tile drains, a water-table, depth, root, condition, a layer.

4. radially, rapidly, efficiently, easily, however, upwards, rather, immediately, below, approximately.

2. Sav to what parts of speech the words from task № 1 under letters А. В, C. D refer. Rewrite suffixes and prefixes typical to these parts of speech.

3. Write out all the predicates from the sentences. Say in what tense and voice they are. Translate the sentences into Russian.

I. This form of irrigation has advantages over other surface irrigation. 2. The water distribution is easily affected by the wind.

3. Subirrigation or subsoil irrigation applies water beneath the ground rather than on the surface. 4. There are, however, a number of disadvantages of sprinkler systems. 5. The initial costs of installing such systems are very high.

4. Put all types of questions (general, special, alternative, disjunctive) to the sentences. Translate the sentences into Russian.

1. A common type of sprinkler head is the revolving one, which distributes water radially. 2. Sprinkler irrigation can be adapted for use on almost all types of soil, especially sandy soils which absorb water rapidly. 3. A uniform application of water is made possible, and the amount arid timing of the irrigation can be easily controlled. 4. To ensure the most economical use of the equipment, a constant supply of water is needed. 5. Lands suitable for this method of irrigation are rather limited, since it requires a special combination of natural conditions.

5. Translate into English.

1. Текст, который я только что прочитал, называется «Методы орошения». 2. Он рассказывает нам о четырех основных способах орошения. 3. Это орошение затоплением, полив по бороздам, орошение дождеванием, внутрипочвенное орошение. 4. При орошении дождеванием почва увлажняется опрыскиванием. 5. Обычный тип опрыскивателя вращающийся, он разбрызгивает воду по кругу. 6. Этот способ орошения имеет преимущества перед другими поверхностными способами: он подходит для всех типов почв, культур; воду можно расходовать рационально; время орошения легко контролируется. 7. Тем не менее, у него есть и ряд недостатков, т.к. нужно поддерживать чистоту и давление воды. 8. Внутрипочвенное орошение - это способ, при котором подпахотный слой увлажняется через поперечные, кротовые или трубчатые дрены. 9. Этот способ орошения требует полного контроля над поднятием уровня воды и др. 10. В заключение я бы хотел сказать, что очень важно выбрать правильный способ орошения, чтобы он был подходящим и эффективным.

6. Translate the text in the written form. . ¹

7. Make up a plan of it.

8. Retell the text according to vour plan.

9. Learn the following words bv heart.

1.	debris	остатки, наносы
2.	elevation	возвышение
3.	moie drain	кротовая дрена
4.	permeable soil	проницаемая почва
5.	revolving	вращающийся
6.	rolling	холмистый
7.	shallow	поверхностный, мелкий
8.	steep	высокий
9.	tile drain	трубчатая дрена
10	enable	давать, создавать возможность
11	uniform application	постоянное использование
12	water-table	уровень воды, высота отметки грунтовых вод