Method of irrigation

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This topic is most important for bsc agri 1st year student.

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WEL COME Presented by Prof. Gawali S.D . Assistant Professor, Dept. of Agronomy College of Agriculture, Nehrunagar Vasantrao Naik Gramin Krishi Mahavidyalay, Nehrunagar.

CONTENT:

CONTENT

A. SURFACE IRRIGATION:

A. SURFACE IRRIGATION There are three principle methods of irrigation viz. 1) Surface 2) Sub surface 3) Aerial, overhead or sprinkler irrigation. A. Surface irrigation: There are 4 types under this method viz. (1) Flood Irrigation or wild flooding. (2) Bed or border method- (Sara and flat beds) (3) Basin method (ring and basin). (4) Furrow method (rides and furrows, broad ridges or raised beds).

1.Flood Irrigation Method:

1.Flood Irrigation Method 1 ) Flood Irrigation- 1) It consist of opening a water channel in a plot or field so that water can flow freely in all directions and cover the surface of the land in a continuous sheet. 2) It is the most inefficient method of irrigation as only about 20 percent of the water is actually used by plants. 3) Water distribution is very uneven and crop growth is not uniform. It is suitable for uneven land where the cost of leveling is high and where a cheap and abundant supply of water is available. It is unsuitable for crops suitable where broadcast crops, particularly pastures, peas and small grains are produced.

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1.Flood Irrigation Method

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I) ADAPTATIONS: 1) An abundant supply of water 2) Close growing crops 3) Soils that do not erode easily 4) Soils that is permeable 5) Irregular topography 6) Areas where water is cheap. II) Advantages:- 1) Can be used on shallow soils 2) Can be employed where expense of leveling is great 3) Installation and operation costs are low 4) System is not damaged by livestock and does not interfere with use of farm implements . III) Disadvantages:- 1) excessive loss of water by run of and deep percolation 2) excessive soil erosion on step land. 3) fertilizer and FYM are eroded from the soil.

2) Bed or border method (Sara and Flat beds or check basin):- :

2) Bed or border method (Sara and Flat beds or check basin):- In this method the field is leveled and divided into small beds surrounded by bunds of 15 to 30 cm high. Small irrigation channels are provided between two adjacent rows of beds. The length of the bed varies from 30 meters for loamy soils to 90 meters for clayey soils. This method is adaptable to most soil textures except sandy soils and is suitable for high value crops. It requires leveled land. It is suitable for crops plant in lines or sown by broadcast. This may also be called a sort of sara method followed locally in Maharashtra but the saras to be formed in this method are much longer than broader.

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I) Adaptations:- 1) A large supply of water 2) Most soil textures including sandy Loam, loams and clays 3) Soil at least 90 cm deep 4) Suitable for close growing crops. II) Advantages:- 1) Provide uniform application and efficient use of water. 2) Require less labour and time. 3) Low maintenance cost. III) Disadvantages:- 1) Fairly large supply of water is needed. 2) Land must be leveled 3) Suited only to soils that do not readily disperse. 4) Drainage must be provided

3) BASIN IRRIGATION:

3) BASIN IRRIGATION 1) This method is suitable for Orchids 0r Fruit crop and other high value crops where the size of the plot to be irrigated is very small. 2) The basin may be square, rectangular or circular shape. A variation in this method viz. ring and basin is commonly used for irrigating fruit trees. 3) Basin irrigation also requires leveled land and not suitable for all types of soil. It is also efficient in the use of water but its initial cost is high. 4) Check basin types may be rectangular, contour and ring basin.

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I) Adaptations:- 1) Most soil texture 2) High value crops 3) Smooth topography. 4) High water value/ha II) Advantages:- 1) Varying supply of water 2) No water loss by run off 3) Rapid irrigation possible 4) No loss of fertilizers and organic manures 5) Satisfactory III) Disadvantages:- 1) If land is not leveled initial cost may be high. 2) Suitable mainly for orchids, rice, jute, etc. 3) Except rice, not suitable for soils that disperse easily and readily from a crust.

4) Furrow method (Ridges and Furrow, Broad ridges, Counter furrow):

4) Furrow method (Ridges and Furrow, Broad ridges, Counter furrow) 1) Row crops such as potatoes, cotton, sugarcane, vegetable etc. can be irrigated by furrow method. 2) Water is allowed to flow in furrow opened in crop rows. It is suitable for sloppy lands where the furrows are made along contours. 3) The length of furrow is determined mostly by soil permeability. It varies from 3 to 6 meters. In sandy and clay loams, the length is shorter than in clay and clay loams.

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I) Adaptations:- 1) Medium and fine textured soils. 2) Variable water supply. 3) Farms with only small amount of equipment. II) Advantages:- 1) High water efficiency.(it is % ratio of water stored in the soil for crop growth and production to total water applied) 2) Can be used in any row crop. 3) Relatively easy in stall. 4) Not expensive to maintain. 5) Adapted to most soils. III) Disadvantages:- 1) Requirement of skilled labour is more. 2) A hazard to operation of machinery. 3) Drainage must be provided.

B. SUBSURFACE IRRIGATION Subsurface irrigation or sub-irrigation may be natural or artificial:

B. SUBSURFACE IRRIGATION Subsurface irrigation or sub-irrigation may be natural or artificial Subsurface irrigation or sub-irrigation may be natural or artificial. Natural sub surface irrigation is possible where an impervious layer or loose surface exists below the root. In artificial sub surface irrigation, perforated or porous pipes are laid out underground below the root zone and water is led into the pipes by suitable means. The method involves initial high cost, but maintaince is very cheap. It is very efficient in the use of water as evaporation is cut off almost completely. This method is adopted in the Israel country.

C. DRIP OR TRICKLE IRRIGATION :

C. DRIP OR TRICKLE IRRIGATION Micro irrigation – The methods in which low volume of water is applied at low pressure & high frequency usually an irrigation interval is in the ranges of 1 to 4 days. A) Drip irrigation:- In drip irrigation the required quantity of water is applied by means of mains, sub mains, manifolds & plastic laterals in the with equally spaced emitters usually laid on the ground surface at low pressure & at low discharge at the root zone of the crop.

C. DRIP OR TRICKLE IRRIGATION :

C. DRIP OR TRICKLE IRRIGATION

C. DRIP OR TRICKLE IRRIGATION :

C. DRIP OR TRICKLE IRRIGATION B) Components of drip irrigation system:- 1) Head- 2) Main line and sub line- 3) Lateral lines- 4) Drip nozzles/Emitters or Drippers- 5) Control valves (Ball valves)- 6) Flush valves- 7) Air release cum vacuum breaker valves- 8) Non return valves- 9) Pressure gauge- 10) Grommet and take off- 11) End capes (end sets)- 12) Filter-

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Head- The head consists of a pump to lift water and produce the desired pressure (about 2.5 atmospheres ) and to distribute water through nozzles. A fertilizer tank for applying fertilizer solution directly to the field along with the irrigation water and filter which cleans the suspended impurities in irrigation water to prevent the blockage of holes and passage of drip and nozzles.

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2) Main line and sub main- 1. Main line- 1) Mains and sub mains are normally of flexible material such as black PVC pipes. 2) The main line convey the water from filtration system to the sub main. 3) They are maid up of rigid PVC pipe (PVC- Poly Vinyle chloride ). 4) They are placed below the ground i.s 60 to 90 cm (2 to 3 ft.) so that they not interface with cultivation practices like deep ploughing and harrowing. 5) The velocity of the mainline is not greater than 1.5m/s.

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2. Sub main line- 1) The sub main convey the water from main line to the lateral. 2) They are maid up of rigid PVC pipe (PVC- Poly Vinyle chloride ). 3) They are buried in ground 2 to 2.5 ft . depth. so that they not interface with cultivation practices. 4) The diameter of sub main is usually smaller than main line. 5) There may be number of sub mains from one main line depending upon the plot size and crop type.

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3. Laterals- 1) Laterals are small diameter flexible pipes, tube like structure made up of LDP (Low Density Polyethylene) or LLDP (Liner low polyethylene ) 2) They are connected to the sub main line. 3) They are maid up of 12 mm, 16 mm, and 20 mm size. 4) Their color is black to avoid the algae growth and effect of ultra violet radiation. 5) They can withstand the maximum pressure of 2.5 to 4 kg/cm2 6) The pressure variation between two extreme points of lateral should not be more than 15-20% and discharge variation should not be more than 10% .

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4. Emitters or Drippers- 1) It is the main component of drip irrigation system for discharging water from lateral to the soil i.e. the plant. 2) They are maid up of plastic such as polythene or polypropylene . 4) The discharge rate is between 1 to 15 LPH.(Littre per hour). 5) The main principle of dripper, is to achieve the minimum discharge with maximum size of water passage. 6) Emitters may be on the lateral or inside the lateral, accordingly they are called online or inline emitters.

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5. Control valves (Ball valves)- 1) Use - There are used to control the flow through particular pipes. 2) Generally they are installed on filtration system, main line and on all sub main. 3) These are made up of gunmetal, PVC, cast iron and their size ranges from 1/2” to more than 5”.

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6. Flush valves - 1) Use - It is provided at the end of each sub main to flush out the water bad dirt’s. 7 . Air release cum vacuum breaker valves - 1) Use - It is provided at the highest point in the main line to release the entrapped air during the start of system and to break the vacuum during shut off. 8. Non return valves – 1) Use - It is used to prevent damage of pump from back flow of water in rising main. 9. Pressure gauge- 1) Use - It is used to indicate the operating pressure at the drip irrigation.

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10. Grommet and take off- 1) Use - It is used to connect the lateral to sub main. 11. End capes (end sets)- 1) Use - These are used to close the lateral ends, sub main ends and main line ends 12. Filter- 1. Gravel filter (Sand filter)- 2. Screen filter – 3. Disc filter- 1) Use - These are used to effective against inorganic sus- painded solids, biological substance and other org. material.

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A) Definition:- Fertigation is the process of application of water soluble solids fertilizer in to the irrigation water. B) Advantages of fertigation- 1) Fertigation eliminates the work of spreading fertilizer. 2) Fertilizer placement is exactly to the root zone of plant and can be uniformly applied. 3) All types of nutrients can be given at a time. 4) Saving fertilizers by avoiding losses due to the leaching. 5) Decrease in potential nutrients looses. 6) Application of as per crop requirement. 6) Optimum production in light soil is possible. 7) Increase fertilizer efficiency. 8) Improvement in 25 to 30% in the quality and quantity of crop production. 9) Uniform distribution.

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C) Disadvantages of fertigation- 1) Toxicity and contaminated:- Caution must be taken whenever fertilizer solution are introduction in to water supply system. 2) Fertilizer suitability:- Slowly water soluble fertilizer such as super phosphate or calcium ammonium phosphate are not suitable. 3) Corrosion:- Sensitive parts of the equipment must be made out of corrosion resistant material.

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D) Types of fertigation equipment:- 1) Ventury injector:- 2) Fertilizer tank:- 3) Injecting pump:-

Advantages Drip irrigation system :

Advantages Drip irrigation system Advantages Drip irrigation system- 1) Water saving is up to 40 to 60% 2) Enhance the plant growth & increases the crop yield 3) Very high irrigation efficiency. 4) Improve efficiency of fertilizers. 5) No soil erosion. 6) Enhances the maturity of the crop. 7) Salty water can be applied. 8) No water loss through runoff, evaporation and percolation. 9) weed can be checked. 10) Fertilizer can be applied. 11) Water saving method and adopted in scarcity method. 12) Increase the cultural practices. 13) Reduce operational labour . 14) Equal amount of water is applied to the soil or plant.

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Disadvantages Drip irrigation system- 1) Initial cost of installation is high. 2) Regular frequent maintainace is high. 3) Only suitable for high value and widely spaced crops. 4) Salinity hazard 5) High technical knowledge is required .

D. SPRINKLER OR OVERHEAD IRRIGATION :

D. SPRINKLER OR OVERHEAD IRRIGATION A) Definition:- It is methods in which water is spread into air and allowed to fall on the ground surface OR Water is forced under pressure through small nozzle/orifice which gets broken up to into droplets and fall back on the ground. B) Adaptability of Sprinkler irrigation- 1) Sprinkler irrigation can be adopted where land reveling is uneconomical and other method of surface irrigation cant carried out. etc. 2) Where it is designed to go for frequent irrigation. 3) Shallow soils. 4) Close growing crops. 5) It is mostly adopted in sandy soil, because of infiltration rate of sandy soil is high.

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C. Advantages- 1) It ensures uniform distribution of water. 2) It is adaptable to most kinds of soil. 3) Fertilizers material may be evenly applied through sprinklers. This is done by drawing liquid fertilizer solution slowly in to the pipes on the suction side of the pump so that the time of application varies from 10 to 30 minutes. 4) Water losses are reduced to a minimum extent. 5) More land can be irrigated. 6) Costly land leveling operations are not necessary . 7) The amount of water can be controlled to meet the needs of young seedling or mature crops.

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D. Disadvantages- 1)  The initial cost is rather very high. 2)  Any cost of power to provide pressure must be added to the irrigation charges. 3)  Wind interferes with the distribution pattern, reducing spread or increasing application rate near lateral pipe. 4)  There is often trouble from clogged nozzle or the failure of sprinklers to revolve. 5) The cost of operations and maintaince is very high. 6) It is suitable for high value crops.

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E. Component- 1)  Pumping set. 2)  Main line. 3)  Lateral line. 4) Sprinkler heads. 5) Debris Screen. 6) Booster pump. 7) Take off valve. 8) Flow control valve.

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E. Component- 1) Pumping set:- Use:- The pump usually lift the water from the source and pushed it through the distribution system and sprinkler. 2) Main line:- The main lines are permanents or portable. Permanent lines are used where crop require full season irrigation and steel pipes or PVC pipes are used for permanent main line. And light weight aluminum pipes are used for mostly portable mainline. Use:- The main line convey the water from filtration system to the sub main.

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3)  Lateral line:- The lateral lines are usually are portable aluminum pipes are usually available in length of 5 m, 6 m, or 12 m. Use- The sub main convey water to the lateral which is turn supply water to the sprinkler. 4) Sprinkler:- It is most important component of sprinkler irrigation system. these are fixed on the riser pipe which is fixed on the lateral. Use:- These are distribute the small water droplets uniformly over the field with out causing runoff, excessive loss due to the deep percolation .(Water drop size- 0.5 to 1.0 mm) Types:-1.Rotating head sprinkler. 2. Fixed head sprinkler.

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5) Debris Screen:- Use:- To keep the system clean and avoid plugging of sprinkler. 6) Booster pump:- When existing pump capacity is insufficient ,booster pump is additionally used. 7) Take off valve:- Use:- used to control the pressure in the lateral line. 8) Flow control valve:- Use:- used to regulate the pressure and discharge of individual sprinklers.

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