Irrigation engineering

Irrigation engineering : in agriculture, artificial watering of the land. Although used chiefly in regions with annual rainfall of less than 20 in. (51 cm), it is also used in wetter areas to grow certain crops, e.g., rice. Estimates of total irrigated land in the world range from 543 to 618 million acres (220 to 250 million hectares), almost half of them in India, Pakistan, and China. The United States had almost 60 million acres (23.8 million hectares) of irrigated farmland in 1991.

In Irrigation engineering Methods of applying water include free-flooding of entire areas from canals and ditches; check-flooding, in which water flows over strips or checks of land between levees, or ridges; the furrow method, in which water runs between crop or tree rows, penetrating laterally to the roots; the surface-pipe method, in which water flows in movable slip-joint pipes; sprinklers, including large-scale center-pivot and other self-propelled systems; and a variety of water-conserving drip and trickle systems. In many cases irrigation is correlated with drainage

 to avoid soil salinity, leaching, and waterlogging. Irrigation may also involve preliminary clearing, smoothing, and grading of land. Especially in areas of high evaporation rates, intensive irrigation can result in excessive quantities of salts accumulating in the upper layers of the soil as water evaporates from the surface, rendering the soil unfit for crop production.

Since prehistoric times water has been diverted from waterways to fields by ditching. Early improvements for raising water included counterbalanced poles with attached water vessels, and adaptations of the wheel and of a pump called the Archimedes’ screw. The use of canals, dams, weirs, and reservoirs for the distribution, control, and storage of water was probably initiated in ancient Egypt. A system of gently sloping underground tunnels (qanats) to deliver water from a subterranean source to distant areas where it is accessed through shafts was developed in ancient Persia and has been widely used elsewhere. In modern times pumps have facilitated the use of underground as well as surface water, but overuse of water in aquifers can exhaust their usable water. Large-scale 20th-century irrigation projects commonly also include water supply, hydroelectric power, and flood control.

 

Methods of Determining duty of water
Methods of Determining duty of water

Methods of Determining duty of water

  Learn:Methods of Determining duty of water,Duty by Inductive Method,Critical Growth Period Basis METHODS OF DETERMINING DUTY OF WATER The duty of water can be found,out by any of the following three methods Inductive method. Critical growth period basis 1. Duty by Inductive Method. This method is based mostly on past experiments and experiences. Various states have developed standard duty tables depending upon. The methods of irrigation adopted by them. Methods adopted by various states to determine discharge in the channels to meet the crop requirements vary. Following are the methods mostly adopted: (A) In this method, the percentages of areas under different crops water allowance for the entire C.C.A. for a particular channel fixed. An example of this method may be 0.17 cumec per 1000 hectares. This method of fixing the duty. (B) the method outlet discharge factors for different crops of the region  standardized. Based on outlet discharge…

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OPTIMUM USE OF WATER
OPTIMUM USE OF WATER

OPTIMUM USE OF WATER

Learn: Optimum use of water, water requirement,Relation between M.C. and growth rate,Relation between yield and water depth. OPTIMUM USE OF WATER The quantity of water supplied to a particular crop during its growth period. Which results in the maximum yield of the crop is known as optimum water requirement. This water requirement includes water supplied by irrigation and by precipitation both. In order to get the maximum yield with least amount of irrigation water. Knowledge of optimum requirement of water for the crop is essential. Supply of irrigation water, both more, and less than the optimum requirement, affects yield adversely. If less than optimum amount of irrigation water is supplied. The plant has to expend extra energy to get moisture from the soil. which would otherwise have been utilised for the growth of the plant. This affects the yield. On the other hand if more than optimum Requirement of water…

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DEFINITIONS OF SOME MORE IMPORTANT TERMS

  Learn: Definitions of some more imporatant terms,Outlet factor,Paleo watering,Kor Watering,Kor Depth, DEFINITIONS OF SOME MORE IMPORTANT TERMS Some of the common terms usually used in regard to the watering of the fields have been explained here. 1. Outlet Factor. This term has already been explained earlier. It is nothing but duty of canal water at outlet. 2. Paleo Watering. This is the watering applied to the fields before sowing the crops. This watering is given so as to develop sufficient moisture in the unsaturated zone of the soil so that seeds may germinate easily. 3. Kor Watering. After sowing, when crops have grown a few centimetres this watering is given. It is the first watering after sowing of the crop. Depth of kor watering is always more than the subsequent watering tobe given to the crops in its growth or base period. 4. Kor Depth. The depth of water…

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Water requirements of crop
WATER REQUIREMENTS OF CROPS

Water requirements of crop

FACTORS AFFECTING WATER REQUIREMENTS OF CROPS The following are the possible factors that affect the water requirements of crops. Texture and structure of the soil and its moisture storage capacity. Position of the groundwater table. The slope of the ground. Drainage conditions. Climatic conditions like rainfall temperature, wind movement, and relative humidity. The system of irrigation adopted. The intensity of irrigation. Type and amount of manure applied to fields.

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Methods of improving duty

 METHODS OF IMPROVING DUTY The factors affecting the duty have been explained in previous article of this chapter. If these factors are somehow made less effective the duty of water can be considerably increased. Methods of improving duty have been enumerated as follows: By selecting such method of applying water. which would cause least wastage by way of seepage, percolation, and evaporation. Land should be properly ploughed and levelled so that a thin sheet of water may evenly be spread over it. The fields should be frequently ploughed. This measure reduces loss of moisture specially. when ground water is within capillary reach of the ground surface. Fields should be divided into small kiaries. Smaller the size of kiaries more will be the duty of water. Area to be irrigated should be located as near the canal as possible. This reduces coveyance losses and duty is increased. In other words idle…

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FACTORS AFFECTING DUTY
FACTORS AFFECTING DUTY AND METHODS

FACTORS AFFECTING DUTY

FACTORS AFFECTING DUTY The duty of water depends upon following factors. 1. Soil characteristics through which canal runs. If canal is unlined and soil through which it flows is coarse grained. Seepage and percolation losses will be too much and duty of water will be reduced. If on the other hand canal is either lined or runs through fine grained soil. The losses will be considerably small and duty of water will be more. 2. Soil characteristic of fields. If soil of the field is deep coarse grained, percolation losses will be more. If, however, a hard pan is present at a depth of 1 or 2 m. The percolation losses will be less and duty will be more. 3. Undulated fields. If fields which are to be irrigated are quite undulated, the duty of water will be less. Lower portions are filled with more water whereas higher portions get…

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WATER REQUIREMENTS OF CROPS
WATER REQUIREMENTS OF CROPS

WATER REQUIREMENTS OF CROPS

WATER REQUIREMENTS OF CROPS The subject of water requirements for crops is of direct significance wherever irrigation is practiced. The areas may be divided into three categories namely— arid region, semi-arid region, and humid region. Growing of crops in arid regions is almost impossible without irrigation as rainfall in this region is very rare. In semi-arid regions irrigation may be optional but crops like sugar cane, vegetables, rice, etc. requiring more of water can only be grown by irrigation. In humid regions, irrigation plays a protective role against possible failure or deficiency of rainfall during the crop season.   The water requirement of a particular crop does not remain uniform in different areas. It varies according to variation in climate, rainfall, and type of soil. India is a very large country with having a lot of variation in its different areas as regards rainfall and type of soil. Hence water…

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METHODS OF IMPROVING FERTILITY OF LAND
METHODS OF IMPROVING FERTILITY OF LAND

METHODS OF IMPROVING FERTILITY OF LAND

Learn: Methods of improving the fertility of the land, Organic manure, Chemical manure, Green manure, Leaching method, craping the saltish crust, Surface drainage. METHODS OF IMPROVING FERTILITY OF LAND If deficiencies of any land are made good it becomes suitable for growing crops. If the land is too clayey it can be improved by adding sand to it. Similarly, sandy soils can be improved by adding a suitable amount of clay to it. Soils can be improved as regards its fertility by adding: Organic manure; Chemical manure; Green manure. Cowdung manure is organic manure. It is available in the village in large amounts, as every villager maintains animals. All the manures manufactured by large companies are chemical manures. Superphosphate, urea, potassium sulfate, are the forms of chemical manures. Green manure is developed by sowing some crops in the field. When crop becomes about 10-20 cm high It is plowed in…

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Harmful salts in soils
Harmful Salts In Soils

Harmful salts in soils

Learn: Harmful Salts In Soils,effect of pH Value HARMFUL SALTS IN SOILS If the amount of harmful salts becomes excessive in the soil no crop can be grown over it. Sodium carbonate, sodium chloride, sodium sulfate, etc. are some of the harmful salts. But of these, sodium carbonate which is also known as white salt is considered to be the most harmful. If the percentage of harmful salts reaches 0.15 percent it affects the production and if this percentage reaches 0.25 percent it renders the land completely barren. Other salts are also present in the soil but unless their percentage crosses the limit they do not affect the growth of the crops. EFFECT OF pH VALUE The pH value of the soil suitable for crops should lie between 6.0 and 8.5. If pH value exceeds 10.5 the land becomes completely unsuitable for crops.  

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Presence Of Water In Soil
Presence Of Water In Soil

Presence Of Water In Soil

PRESENCE OF WATER IN SOIL Water present in the soil may be classified under three heads: Hygroscopic water, Capillary water, Gravitational water. 1.Hygroscopic Water. When a soil sample after having been completely dried in an oven is put in an open atmosphere, It absorbs some amount of water from it. The amount of water so absorbed by the oven-dried soil sample is termed as hygroscopic water. This water is not capable of any movement by the action of gravity force or capillary force. The amount of this water in the soil can vary only if there is a change in the moisture content in the atmosphere. This water is not available for plant growth. 2. Capillary Water. This water is that water content in soil excess of hygroscopic water, which exists in the pore space of the soil, due to molecular attraction. This water is held in the form of…

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