Furrow irrigation

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1. FURROW IRRIGATION

2. Furrow Irrigation Furrows are small channels, which carry water down the land slope between the crop rows. Water infiltrates into the soil as it moves along the slope. This method is suitable for all row crops and for crops that cannot stand water for long periods, like 12 to 24 hours, as is generally encountered in the border or basin methods of irrigation.

3. Furrow Irrigation Water is applied to the furrows by letting in water from the supply channel, either by pipe siphons or by making temporary breaches in the supply channel embankment. The length of time the water is to flow in the furrows depends on the amount of water required to replenish the root zone the infiltration rate of the soil the rate of lateral spread of water in the soil. Furrow irrigation is suitable to most soils except sandy soils that have very high infiltration water and provide poor lateral distribution water between furrows

4. Row crops such as potatoes, cotton, sugarcane, vegetable etc. can be irrigated by furrow method. Water is allowed to flow in furrow opened in crop rows. It is suitable for sloppy lands where the furrows are made along contours. In sandy and clay loams, the length is shorter than in clay and clay loams. Water does not come in contact with the plant stems. There is a great economy in use of water.

5. Advantages : High water efficiency Can be used in any row crop Relatively easy in stall Not expensive to maintain Adapted to most soils.

6. Disadvantages: Requirement of skilled labour is more A hazard to operation of machinery Drainage must be provided.

7. Kinds of Furrow Irrigation Level furrows Graded straight furrows Graded contour furrows Corrugations

8. Level Furrows Small irrigation channels Irrigation water must be applied quickly Using furrows as large as the stream can contain Require extensive land preparation Best suited for soils with moderate to slow intake rate

9. Advantages Adjustability of water quantity applied Doesn’t require change in land layout Efficient application No irrigation water needs to be lost from runoff Use of rainfall can be maximized

10. Disadvantages Difficult to apply in areas of high wind Water ponds damage some crops(potato) Drainage of rainfall can be extensive Furrow needs to be large enough to carry rainfall excess Topography needs to be carefully and regularly maintained

11. Graded Straight Small irrigation channels Relatively flat lands Usually constructed in straight lines Initial irrigation stream needs to be more than intake rate in order for stream to advance Suitable for crops planted in rows

12. Advantages Can be used with both large and small irrigation streams Furrows can act as channels to carry and dispose excess surface water High application efficiency

13. Disadvantages High labor requirements (unless automated) Uniform application is difficult for soils with high intake rates Land needs to be relatively flat and have very little slope Field must be carefully leveled Surface runoff collecting facilities need to be provided

14. Graded Contour Small graded irrigation channels With uneven or warped surfaces Furrows are designed to fit the general curves of the land Water application is the same as with graded straight furrows Can be used on most soils except sandy soils and others that crack easily

15. Advantages Best for safely irrigating steep land Can also be used with both large and small irrigation systems High application efficiency Most of the same advantages as graded straight furrows

16. Disadvantages Takes a lot of time to layout field Grassed waterways and structures are usually needed to carry tailwater down the slope Large capacity furrows need to built and maintained through the whole season Rodent control is necessary to avoid breakage and flow of water from high to low streams

17. Corrugations Small, closely spaced channels Irrigate close-growing crops Conform to the slope of land because of the small capacity of water channels Land slopes must be uniform to increase efficiency

18. Advantages Low costs for land preparation Best suited for areas of low rainfall Especially good for irrigating soils that tend to bake or crust

19. Disadvantages Not essential to slopes of less than 1% or to high rainfall areas due to erosion hazard Small flows of water

20. Land Preparation Uniform topography Divide fields into design areas No sharp turns Rectangular Equal in length

21. Furrow Shape Heights of ridges vary between 15-40 cm Cross section must be large Modified by the water as it moves along

22. Furrow Length Longer=more efficient Limitations on length: Intake rate of the soil Grade of the furrows Rainfall intensity Depth of application Field dimensions Location of soil boundaries Shouldn’t exceed 1,320 feet

23. Max Slopes for Various Soil Types Soil Type Sand Sandy loam Fine sandy loam Clay Loam *A min slope of ~0.05% required to ensure surface drainage Maximum slopes* 0.25 0.40 0.50 2.50 6.25

24. Subsurface irrigation methods As suggested by the name, the application of water to fields in this type of irrigation system is below the ground surface so that it is supplied directly to the root zone of the plants. The main advantages of these types of irrigation is reduction of evaporation losses and less hindrance to cultivation works which takes place on the surface. There may be two ways by which irrigation water may be applied below ground and these are termed as: • Natural sub-surface irrigation method • Artificial sub-surface irrigation method

25. Natural Sub-surface irrigation method Under favorable conditions of topography and soil conditions, the water table may be close enough to the root zone of the field of crops which gets its moisture due to the upward capillary movement of water from the water table . The natural presence of the water table may not be able to supply the requisite water throughout the crop growing season. However, it may be done artificially by constructing deep channels in the field which may be filled with water at all times to ensure the presence of water table at a desired elevation below the root zone depth .

26. Natural Sub-surface irrigation method Though this method of irrigation is excellent from both water distribution and labour saving points of view. it is favorable mostly for the following • The soil in the root zone should be quite permeable • There should be an impermeable substratum below the water table to prevent deep percolation of water . • There must be abundant supply of quality water that is one which is salt free, otherwise there are chances of upward movement of these salts along with the moisture likely to lead the conditions of salt incrustation on the surface.

27. Artificial subsurface irrigation method The concept of maintaining a suitable water table just below the root zone is obtained by providing perforated pipes laid in a network pattern below the soil surface at a desired depth. This method of irrigation will function only if the soil in the root zone has high horizontal permeability to permit free lateral movement of water and low vertical permeability to prevent deep percolation of water. For uniform distribution of water percolating into the soil, the pipes are required to be very closely spaced, say at about 0.5m.

28. Artificial subsurface irrigation method Further , in order to avoid interference with cultivation the pipes have to be buried not less than about 0.4m below the ground surface. This method of irrigation is not very popular because of the high expenses involved, unsuitable distribution of subsurface moisture in may cases, and possibility of clogging of the perforation of the pipes.

29. Sprinkler Irrigation System Sprinkler irrigation is a method of applying water which is similar to natural rainfall but spread uniformly over the land surface just when needed and at a rate less than the infiltration rate of the soil so as to avoid surface runoff from irrigation. This is achieved by distributing water through a system of pipes usually by pumping which is then sprayed into the air through sprinklers so that it breaks up into small water drops which fall to the ground.

30. Sprinkler Irrigation System The system of irrigation is suitable for undulating lands, with poor water availability, sandy or shallow soils, or where uniform application of water is desired. No land leveling is required as with the surface irrigation methods. Sprinklers are, however, not suitable for soils which easily form a crust. The water that is pumped through the pump pipe sprinkler system must be free of suspended sediments. As otherwise there would be chances of blockage of the sprinkler nozzles.

31. Sprinkler Irrigation System In sprinkler irrigation, water is conveyed under pressure through pipes to the area to be irrigated where it is passed out through or sprinklers the system comprises four main parts i .  Power generator ii.  Pump iii. Pipeline and iv. Sprinkler

32. Sprinkler Irrigation System The power generator may be electrical or mechanical. A centrifugal pump may be used for suction lift up to 37 to 50 cm . A piston type pump is preferable where water is very deep. The pipe consists of two sections, the main line and the laterals. The main line may be permanently buried underground or may be laid above ground, if it is to be used on a number of fields . The main pipes are usually made of steel or iron .

33. Sprinkler Irrigation System The laterals are lightweight aluminum pipes and are usually portable . The sprinkler nozzles may be single or double, revolving or stationery and mounted or riser pipes attached to riser. Each sprinkler head applies water to circular area whose diameter depends up on the size of water, which varies from ¼ to ¾ inch per hour is determined by selecting the proper combination of nozzles.

34. Sprinkler Irrigation System Adaptations: 1 ) A dependable supply of water 2 ) Uneven topography 3 ) Shallow soils. 4 ) Close growing crops .

35. Sprinkler Irrigation System Advantages : 1) It ensures uniform distribution of water 2) It is adaptable to most kinds of soil. 3) It offers no hindrance to the use of farm implements 4) 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.

36. Sprinkler Irrigation System Advantages : 5 ) Water losses are reduced to a minimum extent 6) More land can be irrigated 7) Costly land leveling operations are not necessary and 8) The amount of water can be controlled to meet the needs of young seedling or mature crops.

37. Sprinkler Irrigation System Disadvantage: 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.

38. Sprinkler Irrigation System Disadvantage: 5) The cost of operations and maintaince is very high. Labour requirement for moving a pipe and related work approximately nearly one hour per irrigation. 6) It requires a dependable constant supply of water free slit and suspended matter and 7 ) It is suitable for high value crops