S.Seifullin Kazakh Agro-Technical University

Technical faculty

Department of Agricultural and post-harvesting Machines

LABORATORY WORK

) on subject) on subject on subject «Adjustment and linkage of Agricultural machines»

Theme: Farm irrigation

Astana 2012

Considered and approved at the meeting of Methodological Council of S.Seifullin Kazakh Agro-Technical University Protocol №___ «___»_______________2012

«APPROVED» Chairman of Methodological Council of S.Seifullin Kazakh Agro-Technical University Protocol №___ _____________A.M.Abdyrov «___»_______________2012

Authors: Yeskhozhin К. – Candidat of Techical Sciense, Associate Professor of the Department of Agricultural and post-harvesting Machines.

Educational-methodical __________ is designed for training on discipline "Fundamentals of tractors" for students on specialty 5B080600 - "Agricultural techniques and technology"

Educational-methodical instructions are made according to the working curriculum of specialty.

Methodical instructions are intended for students of specialties 5В080600 – « Agricultural techniques and technology» and includes laboratory occupation tasks and independent work, educational literature lists and control questions for self-examination.

Reviewers: Doctor of Technical Science, Professor S.O. Nukeshev;

Reviewed and recommended at a meeting of the Department of Agricultural and post-harvesting Machines .

Protocol № ___, of "__" ___________ 2012.

Reviewed and recommended at a meeting of the methodical commission of Technical Faculty.

Protocol № ___, of "__" ___________ 2012.

Definition - Under the term ''Irrigation/' as applied to agricul­ture, is included all of the operations or practices in artificially applying water to the soil for the production of crop.

Irrigation at the present time, considered from the standpoint of the irrigation engineer, includes the conservation and storage of the water supply, the carrying of water from the source of supply to the irrigable area and distributing it to the land. It involves, in many cases, the development and bringing to the surface, waters from underground sources, and also the raising of water by pumping or other means to lands which cannot be reached by a gravity Bow from the source of supply. Closely related to irrigation is also the question of drainage for the removal of excess waters from the land.

Drainage, either by natural or artificial means, or equally as important as irrigation to insure successful agricultural operations. It is generally impracticable to apply water to lands sufficient to grow crops without a portion of it being wasted either on the surface or underground. This waste, or excess, must be removed either through natural outlets or artificially constructed drainage ditches, in order to prevent the land becoming waterlogged or charged with alkali and rendered unfit for successful farming.

In addition to the physical problems involved in irrigation, economic questions must also be considered. These questions in­volve estimates on the value of lands to be irrigated and a comparison of these values with the cost of constructing irrigation works in order to determine whether the project is feasible from a financial standpoint.

Needs and Benefits – The need of irrigation arises from lack of natural rainfall at the times when required by crops. In some regions the total precipitation annually is apparently adequate for all vegetation, but frequently the rain occurs at seasons when it is not needed and falls at critical times, thus irrigation must be prac­tised during the season of summer drought. Under these conditions it may be considered as a form of insurance, while in the truly arid areas it is an absolute necessity.

The benefits which are derived from irrigation are those which arise from the ability to supply the amount of water needed by the growing plants in the quantity and at the times when it is most bene­ficial in crop production. In the arid or dry regions where rainfall is irregular or spasmodic there are consequently few clouds, the sunshine reaches the soil without obstruction and where water can be supplied this continuous unobstructed daily sunshine stimulates plant growth to a high degree, because of the well-known fact that all life and growth on the earth is maintained by the sun's energy.

Irrigation affords ideal conditions for agriculture, since with the life-giving sunlight and a means to supply moisture at proper times and in the exact quantity needed, agriculture can be reduced more nearly to scientific accuracy.

It is largely because of these facts that agriculture in an arid region offers larger opportunities for returns from a given area than in the humid regions, where dependence must be placed upon an erratic rainfall. The amount of sunlight in the humid areas and consequently the forces leading to growth are limited by the many cloudy days. Ignoring this fact, it has sometimes been urged that the same amount of energy and investment put in the agricultural operations of the eastern part of the United State should be equally or more productive than in the western, but, in this statement, there is a neglect of consideration of this all important item of total amount of sunlight.

1. Surface irrigation

Surface irrigation refers to methods of water application where a body of water, of some depth, is applied to one end of a bay or furrow. Because the bay or furrow is constructed with a slight gradient and because the body of water has a natural tendency to spread, water flows down the bay or furrow in a sheet or stream, infiltrating as it goes.

These methods are often referred to as flood irrigation, but that is not a good description for furrows or bays where reasonable control over the water movement can be created. They are also sometimes referred to as gravity irrigation methods since gravity is the driving force causing water flow, once water is delivered to the bay or furrow.

Much of Australian irrigation is performed with surface irrigation, but there are some distinct limitations with this method of watering.

1.1. Surface irrigation methods.

A number of different versions of surface irrigation are practiced. Furrow irrigation is employed for irrigation of row crops. For field crops, border check irrigation is the most com­mon, but other versions are also in use, their selection de­pending on die slope (or lack of it) at die site, die crop grown, die availability of water, and die degree of control required over water flow.

Figure 5.1 Furrow irrigation of cotton. In this example, water is siphoned from the supply channel to the head of the bay.

Furrow irrigation. Crops are established in raised beds, enabling water to flow down defined furrows. Successful irrigation requires water to soak laterally into the bed as well as downward into die root zone. Furrow spacing is therefore partly determined by the hydraulic conductivity of die soil and subsoil, but also by preferred crop row spacing and machinery requirements.

Figure 5.2 Below, Furrow irrigation of grapes, using above ground low-pressure delivery pipe. Below right, Furrow irrigation of citrus, from buried pipe and risers in this orchard.

Water is admitted to the head of me furrow by a siphon in the case of water delivered in open channels. Low pressure gated pipe or fluming is also available, and this occupies much less land area man channels (some can also be buried). It is well suited to high value crops where land area may be lim­ited, or where seepage from a channel would be excessive.

The length of furrow is determined by me slope along the furrow and soil infiltration characteristics, since these deter­mine both the travel speed of the wetting front as it proceeds down the furrow (and therefore the time taken to reach the end of the furrow, and the time water is in contact with the soil) and the amount of water entering the profile. These are characteristics specific to each site. Other factors include the amount of earthmoving required to create the desirable slope for the particular soil type, the shape of the field, and a pref­erence for uniform furrow lengths in each field to assist crop management.

Furrows are normally constructed down the slope, but occasionally furrows are located on the contour to enable this method of irrigation on steeper slopes (usually for or­chards and plantations).

For annual crops, the field is cultivated after harvest, and beds are reconstructed before the next planting. This can have long term detrimental effects on soil structure, organic mat­ter levels, and activities of soil organisms. Some farms have established permanent beds; ie the beds and furrows are al­ways retained. This requires a re-think of crop management techniques, and machinery requirements, but significant im­provements in crop performance have been reported. Improve­ments are due not only to better soil quality in the beds, but also due to improved timeliness of operations.

Border check irrigation. This method is used extensively for a wide range of grain and fodder crops and pastures. A series of bays are formed within each field, running down the slope. The borders of each bay are formed by constructing small earthen check banks (hence border check). Water is admitted to the head of the bay using syphons, gates or pipes in or over the wall of the supply channel. It quickly spreads across the head of the bay, and a wetting front proceeds down the bay.

Like furrow irrigation, the length of the bay is determined according to the slope and soil infiltration characteristic. The cross slope of a bay is limited to 25 mm (preferably less) so this will partly determine the width of bay. Check banks are a possible nuisance to machine operations, so it is preferably to have bays as wide as possible. If they are too wide, uneven watering will result.

Naturally, the surface of the bay must be built and main­tained at the correct, uniform gradient. Unevenness in die bay surface will create uneven watering and poor drainage, reducing crop performance. This is noticeable just after irri­gation (or moderate rainfall) where water may pond on die lower parts of die bay for too long.

Where bay cross slope is a problem, die surface of die bay can be corrugated. This helps guide water down die bay, pro­viding a more even watering, without interfering with crop management.

Figure 5.3 Border check irrigation. In this example, water is admitted to the bay by а pipe in the wall of the supply channel.

Where cross slopes are excessive, check banks can be con­structed on the contour rather than down die slope, provided die vertical interval between adjacent banks is 25 mm or less. This will tend to give uneven watering, and the bay width is likely to be uneven. From a technical and management point of view, it may be preferred to landscape the area to give uniform width and grades to the field.

Other versions of surface irrigation. On flat sites where drainage is difficult at the end of irriga­tion, the borders of irrigation bays can be formed by ditches instead of check banks.

For irrigation of rice, level bays are formed and flooded, water flowing continuously from bay to bay during the irri­gation season. Hillside flooding is occasionally practiced for irrigation of pasture, where a ditch delivers water approxi­mately on the contour above the irrigated area. A temporary check is placed in the channel, water builds up in the channel and floods over the side.

Figure 5.5 Earthmoving under way using a tractor drawn scraper. The operating height of this is adjusted in response to a laser signal. The mast on the machine carries the laser receiver; the laser emitter is mounted on a tower near the centre of the field.