Surface irrigation methods

 

There are three general methods of applying irrigation water to the land.

In the surface irrigation the water either is ponded on the soil or allowed to flow continuously over the soil surface for the duration of the irrigation.

In sprinkler irrigation the water is conveyed above the field in pipes, and the soil acts as a storage reservoir.

In subirrigation the water flows underground, and the capillary water moves upward toward the surface of the land.

Surface irrigation includes the general methods of flood and furrow and corrugation irrigation. (1)

In flood irrigation, water is permitted to cover the surface of the land in a continuous sheet. (2)

Flood irrigation includes several methods: border strip, basin, contour or bench border irrigation, wild flooding and others. (3)

The object of border strip irrigation is to advance a sheet of water down a narrow strip between low ridges or borders and to get the water into the soil as the sheet advances. The ridges should be low and rounded so they can be planted with the strips and no land lost to production.

Border strip irrigation is well adapted for all close – growing crops and is used for some row crops, such as cotton.

Basin irrigation is adapted especially to flat lands. It consists of quickly filling a diked area with water to the desired depth and allowing the water to percolate into the soil. It is desirable for close – growing crops and orchards and for rice.

Contour, or bench border, irrigation is adapted to fairly uniform, moderate slopes. Border strips are laid out across the slope and the ridges are constructed parallel to each other.

In wild flooding the stream of water is diverted from its course and allowed to spread out over the field at random. It is not recommended, because the low spots in the field will get too much water and the high spots will receive none.

Furrow irrigation is the most common method of applying water to row crops. Water is applied in the furrows between the rows of plants. As water runs down the row, parts of it is being absorbed all along the furrow. It is adapted to all row crops, truck crops, orchards, vineyards, and berry patches on gentle slopes.

Corrugation irrigation is well adapted to close – growing crops on sloping lands and to soil slow to take water. The water is applied in small furrows running down the slope from the head ditch. Corrugation irrigation provides uniform wetting and prevents erosive water accumulation on land too steep for borders or basins and make use of small irrigation streams.

 

NOTES

 

1. flood irrigation орошение сплошным заливом

furrow irrigation орошение по бороздам

corrugation irrigation орошение по мелким бороздам

2. in a continuous sheet непрерывным тонким слоем

3. border strip irrigation полив напуском по полосам

basin irrigation лиманное орошение

contour or bench border irrigation контурно – бороздное орошение

напуском

wild flooding метод дикого напуска

 

1. Ответьте на вопросы.

1. What are the general methods of applying irrigation water to the land?

2. How is the water applied to the land in surface irrigation?

3. What are the methods of surface irrigation?

4. How is the water applied in furrow irrigation?

5. How is the water applied in corrugation irrigation?

 

2.Составьте небольшие, предложения используя следующие слова.

General method, surface irrigation, across the slope, to make use, the stream of water, in this method, between field ditches, land too steep, close – growing crops, to be under way, arid areas.

 

3.Переведите предложения на английский язык.

1. Когда вода протекает по бороздам, она всегда уносит с собой некоторое количество почвы.

2. Наиболее частой проблемой при бороздном поливе является проблема эрозии.

3. Метод полива по бороздам особенно удобен, когда источники воды слишком малы для орошения методом напуска по полосам или затопление по чекам.

4. Хлопчатник обычно высевается на заранее подготовленные гряды, которые перед самым посевом обильно (heavily) поливаются.

5. Для пастбищ рекомендуется поливы по полосам или по чекам.

4.Перескажите текст.

TEXT 2

Sprinkler irrigation

 

In sprinkler irrigation the water is sprayed into the air and allowed to fall on the land surface in a uniform pattern. This method came into widespread use because it could be adapted to most sites and crops.

The advantages of sprinkler irrigation, properly installed and operated, are:

Erosion can be controlled. Safe irrigation is possible on land too steep for the efficient use of other methods.

Uniform application is possible on all kinds of soil. On sandy soils that have high intake rates, (1) sprinkler irrigation distributes water better than other methods do.

Land preparation is not required. More land is available for cropping. Field ditches, corrugations, and dikes are not needed.

Small streams of irrigations water can be used efficiently.

The limitations are: rather high initial cost of installation. Much water may be lost due to evaporation and wind.

A constant water supply is needed for the most economical use of equipment. The water must be clean and free of sand and debris.

Tight soils, which have slow intake rates, cannot be irrigated efficiently in hot, windy climates.

Three types of sprinkler systems are used to irrigated farm crops: rotating sprinkler heads, fixed jets, perforated pipes. (2) Rotating sprinkler – head systems are the more widely used type.

Each rotating sprinkler head applies water to a given area. This area is governed by the nozzle size and the water pressure. Sprinklers in the low – pressure range (3) have small area of coverage. Medium – pressure sprinklers (4) cover larger areas and have a wide range of precipitation rates. (5)

High – pressure sprinklers cover larger areas, and precipitation rates are higher than for the moderate or medium pressures.

The sprinkler system includes the pumping plant to provide needed pressure, the sprinkler, the riser pipe, the main pipeline, and the lateral distribution pipe. Sprinkler systems are classified as (1) permanent installations, with buried main and lateral lines, (2) semipermanent, with fixed main lines and portable laterals, and (3) fully portable systems.

Sprinklers with perforated pipes deliver water through very small holes, drilled at close intervals along a segment of the circumference of a pipe.

Electric motors and internal – combustion engines are used to drive the pumps.

Notes

 

1. intake rates скорость поглащения

2. rotating sprinkler heads дождевальный аппарат с

вращающимися насадками

fixed jets неподвижные аппараты

perforated pipes перфорированные трубы

3. sprinklers in the lowpressure range низконапорные дождевальные

системы

4. medium – pressure sprinklers средненапорные дождевальные

аппараты

5. precipitation rates интенсивность дождя

 

1. Ответьте на вопросы.

1. Why did the method of sprinkler irrigation come into widespread use?

2. What are the advantages of sprinkler irrigation?

3. What types of sprinkler system are used to irrigate farm crops?

4. What does the sprinkler system include?

5. How are sprinkler systems classified?

 

2. Закончите предложения данными ниже словами.

1. The uniformity of distribution with sprinkler method is directly affected by … . 2. Portable mains are more economical when a sprinkler system is to be used on any of a number of … . 3. The permanent lines should be buried so as to be out of the way of farming … . 4. Water supplies, including source, quantity, and quality, should be investigated as an early step in the design of a … .

……………………………………………..

sprinkler system, operations, fields, wind.

 

3. Переведите предложения на английский язык.

1. Дождевальную систему следует проектировать так, чтобы полив производился с наименьшим расходом средств в течение года.

2. Ширина полосы, орошаемой перфорированной трубой, зависит от размера отверстий и напора воды.

3. Им надо будет использовать средненапорные дождевальные системы на тех полях.

4. Орошение дождеванием можно использовать почти для всех сельскохозяйственных культур (за исключением риса и джута) и почти на всех видах почв.

 

4.Перескажите текст с опорой на новые слова.

TEXT 3

Subirrigation

Subirrigation is a method of applying water beneath the ground surface. It is usually done by creating an artificial water table and maintaining it at some predetermined depth, usually 12 to 30 inches * below the ground surface for farm crops. Moisture reaches the plant roots through capillary movements. Application efficiencies (1) vary from 30 – 50 per cent in some areas up to 70 – 80 under favorable conditions.

Subirrigation requires permeable soil provided that the soil permeability in the rooting zone is homogeneous, and salinity is not a potential hazard. For successful subirrigation, an adequate supply of water of good quality must be available throughout the growing season. The topography must be nearly level and smooth.

A barrier against excessive losses through deep percolation must exist in the soil profile. The barrier may be a relatively impervious layer in the substratum. The distribution system must consist of a well - planned system of main ditch, field laterals, and structures, which will permit the water table to be raised to a uniform depth below the ground surface over the entire areas. An adequate outlet for the draige of the irrigated must be provided for, particularly in humid areas.

The principles involved in subirrigation are the same in all areas, although the means of introducing water into the soil profile may differ. An artificial water table is created over a natural barriers that prevents deep percolation of the water.

Water may be introduced into the soil profile through open ditches, through mole drains, or through tile drains. (2) The first way is most widely used because it is relatively inexpensive and is adapted to all the soil types that can be subirrigated. Mole and tile drains can be used in organic soil.

The main crops so irrigated are potatoes, beets, onion and corn. An effective drainage system has to be provided so that the water table can be lowered rapidly when necessary and harmful salts can be leached out of the profile.

The entire system, when adequately planned, installed, and maintained, provides excellent drainage during the rainy season.

Under limited situations, subsoil irrigation may be a very desirable system of irrigation. In general, however, it must be used with great caution. Danger from waterlogging and salt accumulation is great.

 

 

Notes

1. Application efficiency коэффициент полезного действия

оросительной воды

2. through mole drains, or through tile drains при помощи кротовых дрен или

гончарных дренажных труб

 

1. Ответьте на вопросы.

1. How do we apply water in subirrigation?

2. What soils does subirrigation require?

3. State the main conditions necessary for successful subirrigation?

4. How many water be introduced into the soil profile in subirrigation?

5. What are the main crops so irrigated?

 

2. Переведите на английский язык.

1. Система подпочвенного орошения должна быть тщательно спроектирована, а поверхность выровнена так, чтобы глубина контролируемого уровня воды под поверхностью почвы была одинакова на всей площади.

2. При кротовом подпочвенном орошении вода протекает по кротовинам (through the mole - passagers) проделанным кротовым плугом или дренажно-кротовой машиной.

3. При поверхностных методах полива вода на орошаемой площади используется менее равномерно (less evenly) по сравнению с дождеванием или подпочвенным орошением.

 

3.В чем заключается внутрипочвенный метод орошения?

 

 

Тексты по специальности.

TEXT 1