1. Selecting an Irrigation System
Ronald F. Gronwald
Water Management Engineer
USDA NRCS Greensboro, NC

2. An Irrigation System is more than the Application Method
Source of water
Management of water
Conveyance of water
Application of water
Capture and reuse (Tailwater Recovery)

3. 1 Field Source 2 1 3 7 1 Pressure flow to field
2 Sprinkler application
3 Runoff
4 Capture
5,6,7 Return flow
Tailwater Pond 4 6 5

4. Irrigation Systems Surface Irrigation Subsurface Irrigation
Sprinkler Irrigation
Microirrigation
Self Explanatory

5. Surface Irrigation Water applied by gravity flow
Basin Irrigation – Entire field is flooded
Furrow Irrigation – Water fed into small channels
Border Irrigation – Strips of land divided by low dikes are flooded sequentially
Self explanatory

6. Basin Irrigation
Basins are flat areas of land, surrounded by low levees or berms The levees prevent the water from flowing to the adjacent fields. Basin irrigation is commonly used for rice grown on flat lands or in terraces on hillsides .

7. Furrow Irrigation
Furrows are small, parallel channels, made to carry water in order to irrigate the crop. The crop is usually grown on the ridges between the furrows

8. Suitable crops rice (grows best when its roots are submerged
pastures, e.g. alfalfa, clover
trees, e.g. citrus, bananas
Crops which are broadcast, such as cereals (Basin and Border Irrigation)
Row crops (Furrow Irrigation)
Not suited to crops which cannot stand in wet or waterlogged conditions for periods longer than 24 hours. (root and tuber crops)
Potatoes
Beets and carrots (require loose, well-drained soils)

9. Suitable soils and land slope
Flatter land surfaces are best suited to surface irrigation methods
Loamy soils are best (to avoid permanent saturation of the soil)
Sands are not recommended for surface irrigation as, due to the high infiltration rate, percolation losses can be high.

10. Water requirements
A high volume, intermittent flow rate is required

11. Advantages of Surface Irrigation
It is the simplest of all irrigation systems
Low initial cost
Low energy costs if gravity can be used to supply the water
Works well in odd shaped fields

12. Disadvantages of Surface Irrigation
High maintenance requirements
Inefficient in water use
Nutrients and pesticides are lost by deep percolation below the root zone
Is not suitable for crops which grow below ground such as potatoes, peanuts, sugar beets and carrots.

13. Subsurface Irrigation
Irrigation water is applied below the ground surface, thus raising the water table to the crop root zone

14. Suitable Crops
Most crops are well suited for subsurface irrigation except very deep rooted crops such as alfalfa and cotton.

15. Suitable Slopes
Works best on flat fields

16. Suitable Soils
The best suited soils have an impermeable layer 5 or more feet below the surface
Water is supplied to the roots by upward capillary action (upflux). Medium textured soils are best. (Fine sandy loams)

17. Advantages of Subsurface Irrigation
Permits storage of water in the lower soil profile
Reduces pumping costs
Can be incorporated into an existing drainage system with low additional cost
Captures plant nutrients at or near the water table for future use by plants

18. Disadvantages of Subsurface Irrigation
Labor intensive to adjust elevation of weirs to change from drainage mode to irrigation mode and back again after heavy rains
System cost can be high in soils with low hydraulic conductivity or rolling topography
Water quality must be high

19. Sprinkler Irrigation

20. Sprinkler Irrigation Water is applied similarly to natural rainfall
Pumps supply water under pressure
Water is distributed through a system of pipes to sprinkler heads
Water breaks up into small water drops which fall to the ground
Must be designed and operated to ensure a uniform application of water
Self explanatory

21. Types of Sprinkler Systems
Hand Move or Wheel Line
Big Gun
Solid Set
Center Pivot
Linear Move
LEPA (Low Energy Precision Application)
LESA (Low Elevation Spray Application)
LPIC (Low Pressure IN Canopy)
MESA (Mid Elevation Spray Application)
Variable Rate

22. Suitable crops Row crops Field crops Tree crops
Big Gun not recommended for irrigation of delicate crops such as lettuce that may be damaged by large drops.

23. Suitable slopes Adaptable to any farmable slope, uniform or undulating
Best when operated parallel to the land contour (to minimize pressure changes along the lines)

24. Suitable soils Best suited to sandy soils with high infiltration rates
Adaptable to most soils if runoff is avoided
Not suitable for soils which easily form a crust (use fine sprays to avoid crusting)

25. Water requirements
The best water sources for a sprinkler system are a wells and ponds.
Low volumes but a continuous supply is needed

26. Traveler (Big Gun)

27. Typical Layout

28. Advantages of Travelers (Big Gun)
Low initial cost
Very mobile - can be used in multiple fields
Works well in odd shaped fields
Can be used to apply manure or lagoon effluent

29. Disadvantages of Travelers
Requires high operating pressure
Uses more energy than other systems
Requires a grassed travel lane
Delivers large droplets which may damage some plants or damage soil surface
Has high instantaneous delivery rate

30. Hand Move System

31. Typical Layout

32. Advantages of Hand Move Systems
Low initial cost
Works well in odd shaped fields

33. Disadvantages of Hand Move Systems
High labor costs
Must be moved from once to 3 times a day
Difficult to use on large fields or with tall crops such as corn

34. Wheel Line or Side Roll Systems

35. Typical Layout

36. Advantages of Wheel Line Systems
Low initial cost
Works well in level fields that are square or rectangular
Can be used in trapezoidal shaped fields by adding or removing pipe sections from one or both ends
Lower labor cost than hand move systems

37. Disadvantages of Wheel Line Systems
Can only be used on low growing crops
Difficult to move in the direction parallel to the pipe
Rolling topography makes alignment difficult

38. Solid Set Systems

39. Typical Layout

40. Advantages of Solid Set Systems
Can irrigate entire fields at once
Can be used for multiple purposes
Irrigation
Frost protection
Crop cooling
Chemical applications

41. Disadvantages of Solid Set Systems
High cost
Risers and sprinkler heads may be damaged by equipment during the growing season

42. Center Pivot Systems

43. Typical Layout

44. Part-circle pivot system

45. Advantages of Center Pivots
Easy to use
Low labor costs
One system can irrigate a large field
When used with corner attachment, can irrigate almost any size and shape field
Adaptable to many different soils, variable terrain and management objectives.

46. Disadvantages of Center Pivots
High initial cost
Has variable application rates across the system (highest at the outer portion of the system.
Requires a complex control system
Vulnerable to lightning and ice damage
Typically requires three-phase power supply

47. Linear-Move Irrigation System

48. Typical layout

49. Advantages of Linear-move Systems
Easy to use
Low labor costs
One system can irrigate more than one field
Water is applied uniformly across the length of the system
Water intake can be from a ditch or from a drag hose.

50. Disadvantages of Linear-move Systems
High initial cost
Best suited to rectangular fields with a length to width ratio of at least 2:1
It is not well adapted to fields with rolling terrain

51. Sprinkler Options Impact Sprinklers Spray Sprinklers High Pressure
Medium Pressure
Low Pressure
Spray Sprinklers
Fixed
Rotating
Wobbling

52. Impact Sprinkler

53. Fixed Spray Sprinkler

54. Rotating Spray Sprinkler

55. Typical Impact Sprinkler Mount

56. MESA Mid Elevation Spray Application

57. LESA Low Elevation Spray Application

58. LPIC Low Pressure In Canopy

59. LEPA Low Energy Precision Application

60. Micro irrigation
Frequent, low volume, low pressure application of water
Line Source (Drip Tape)
Point Source Drip Emitters
Micro-spray/Sprinkler
Basin Bubblers

61. Suitable crops Orchards Windbreaks Vegetables Berries Grapes
Nursery Stock
Ornamental Plantings

62. Suitable Slopes
Pressure compensating emitters and Micro-sprays can be used on very steep slopes
Drip Tape and Basin Bubblers are best suited for flat or gently sloping ground

63. Suitable Soils Micro-irrigation is suitable for all soil types
It is best suited for soils with high or very variable infiltration rates
It is suitable for highly erodible soils
It is suitable for soils high in gravels, stones and cobbles

64. Advantages of Micro-irrigation
The most efficient irrigation method
Little runoff and evaporation occur
Deep percolation is easily controlled
Systems are easily automated to reduce labor costs
Much of the surface remains dry, reducing weeds
Low tension water availability enhances growth, improves yield and quality

65. Disadvantages of Micro-irrigation
Expensive to install and maintain
A high level of management is required
Clogging is a major problem
Animals, especially rodents can damage plastic pipe less than 4” diameter
Elevation differences can cause poor distribution uniformity unless pressure regulators are used

66. Typical Drip System

67. External Emitters

68. Nursery Drippers

69. In Line Emitter

70. Drip Tape

71. Drip Tape System

72. Drip Tape Under Plastic

73. Micro-Spray Emitter

74. Micro-spray

75. Basin Bubbler System

76. What are the potential efficiencies?
Subsurface Irrigation has an attainable Efficiency of 80 to 90%

77. Summary When selecting an irrigation system consider: Crop Slope Soil
Water Source (quantity and quality)
Ability to capture and reuse tailwater
Labor Availability
Management Level

78. Questions ?
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