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Microirrigation. Microirrigation Delivery of water at low flow rates through various types of water applicators by a distribution system located on the.

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Presentation on theme: "Microirrigation. Microirrigation Delivery of water at low flow rates through various types of water applicators by a distribution system located on the."— Presentation transcript:

1 Microirrigation

2 Microirrigation Delivery of water at low flow rates through various types of water applicators by a distribution system located on the soil surface, beneath the surface, or suspended above the ground Delivery of water at low flow rates through various types of water applicators by a distribution system located on the soil surface, beneath the surface, or suspended above the ground Water is applied as drops, tiny streams, or spray, through emitters, sprayers, or porous tubing Water is applied as drops, tiny streams, or spray, through emitters, sprayers, or porous tubing

3 Water Application Characteristics Low rates Low rates Over long periods of time Over long periods of time At frequent intervals At frequent intervals Near or directly into the root zone Near or directly into the root zone At low pressure At low pressure Usually maintain relatively high water content Usually maintain relatively high water content Used on higher value agricultural/horticultural crops and in landscapes and nurseries Used on higher value agricultural/horticultural crops and in landscapes and nurseries

4 Schematic of a Typical Microirrigation System

5 Advantages High application efficiency High application efficiency High yield/quality High yield/quality Decreased energy requirements Decreased energy requirements Reduced salinity hazard Reduced salinity hazard Adaptable for chemigation Adaptable for chemigation Reduced weed growth and disease problems Reduced weed growth and disease problems Can be highly automated Can be highly automated

6 Disadvantages High initial cost High initial cost Maintenance requirements (emitter clogging, etc.) Maintenance requirements (emitter clogging, etc.) Restricted plant root development Restricted plant root development Salt accumulation near plants (along the edges of the wetted zone) Salt accumulation near plants (along the edges of the wetted zone)

7 Salt Movement Under Irrigation with Saline Water Salt accumulation leached downward by successive water applications Salt accumulation leached radially outward from drip tubing Subsurface Drip Sprinkler/Flood

8 Types of Systems Surface trickle (drip) – Water applied through small emitter openings to the soil surface (normally less than 3 gal/hr per emitter) – Most prevalent type of microirrigation – Can inspect, check wetting patterns, and measure emitter discharges

9 Point Source Emitters in a New Orchard

10 Types of Systems Contd Types of Systems Contd… Spray Spray – Water applied (spray, jet, fog, mist) to the soil surface at low pressure (normally less than about 1 gal/min per spray applicator) – Aerial distribution of water as opposed to soil distribution – Reduced filtration and maintenance requirements because of higher flow rate

11 Types of Systems Contd… Bubbler Bubbler – Water applied as a small stream to flood the soil surface in localized areas (normally less than about 1 gal/min per discharge point) – Application rate usually greater than the soil's infiltration rate (because of small wetted diameter) – Minimal filtration and maintenance requirements

12 Types of Systems Contd Types of Systems Contd… Subsurface trickle Subsurface trickle – Water applied through small emitter openings below the soil surface – Basically a surface system that's been buried (few inches to a couple feet) – Permanent installation that is "out of the way"

13 30 in 60 in Typical Subsurface Drip Tubing Installation for Row Crops 12 – 14 in Non Wheel- Track Row Wetting Pattern Drip Tubing 60-inch dripline spacing is satisfactory on silt loam & clay loam soils

14 System Components Pump Control head Control head – Filters – Chemical injection equipment (tanks, injectors, backflow prevention, etc.) – Flow measurement devices – Valves – Controllers – Pressure regulators

15 System Components, Contd System Components, Contd… Mainlines and Submains (manifolds) Mainlines and Submains (manifolds) – Often buried and nearly always plastic (PVC) Laterals Laterals – Plastic (PE) – Supply water to emitters (sometimes "emitters" are part of the lateral itself)

16 Applicator Hydraulics General General – Need pressure in pipelines to distribute water through the system, but the applicator needs to dissipate that pressure – q e = emitter discharge – K = emitter discharge coefficient – H = pressure head at the emitter – X = emitter discharge exponent (varies with emitter type)

17 Characteristics of Various Types of Emitters

18 Emitter Hydraulics Emitter Type Coefficient, K - Exponent, X Coefficient, K - Exponent, X Emitter Discharge, gpm Operating Pressure 8 psi 12 psi 16 psi Porous Pipe Tortuous Path Vortex/Orifice Compensating

19 Estimating Emitter Exponent & Coefficient Requires discharges q e1, q e2 at two pressures h 1, h 2 Emitter ExponentEmitter Exponent Emitter CoefficientEmitter Coefficient or or

20 Emitters (Point Source) Emitters (Point Source) – Long-path – Orifice – Vortex – Pressure compensating (x < 0.5) – Flushing Line-source tubing Line-source tubing – Porous-wall tubing (pores of capillary size that ooze water) – Single-chamber tubing (orifices in the tubing or pre- inserted emitters) – Double-chamber tubing (main and auxiliary passages) Applicator Hydraulics Contd Applicator Hydraulics Contd…

21 – Sprayers Foggers, spitters, misters, etc Foggers, spitters, misters, etc Relatively uniform application over the wetted area Relatively uniform application over the wetted area Lateral hydraulics Lateral hydraulics – Very much like sprinkler hydraulics, but on a smaller scale – Since there is usually a large number of emitters, multiple outlet factor (F)  0.35

22 Other Design and Management Issues Clogging – Physical (mineral particles) – Chemical (precipitation) – Biological (slimes, algae, etc.) Filtration Filtration – Settling basins – Sand separators (centrifugal or cyclone separators) – Media (sand) filters – Screen filters

23 There are many different types of filtration systems. The type is dictated by the water source and also by emitter size.

24 Filtration Requirements for Drip Emitters Filter openings should be 1/7 th – 1/10 th the size of the emitter orifice inch orifice

25 Plugging Potential of Irrigation Water for Microirrigation

26 Chemical treatment Chemical treatment – Acid: prevent calcium precipitation – Chlorine control biological activity: algae and bacterial slime control biological activity: algae and bacterial slime deliberately precipitate iron deliberately precipitate iron Flushing Flushing – after installation or repairs, and as part of routine maintenance – valves or other openings at the end of all pipes, including laterals Application uniformity Application uniformity – manufacturing variation – pressure variations in the mainlines and laterals – pressure-discharge relationships of the applicators

27 Subsurface Drip Irrigation Advantages High water application efficiency Uniform water application Lower pressure & power requirements Adaptable to any field shape No dry corners (vs. center pivot) Adaptable to automation

28 Subsurface Drip Irrigation Disadvantages High initial cost Water filtration required Complex maintenance requirements –Flushing, Chlorination, Acid injection Susceptible to gopher damage Salt leaching limitations

29 Subsurface Drip-Center Pivot Comparison (¼-Section Field; ET = 0.25 in/day) Subsurface Drip Center Pivot Area Irrigated 160 acres 125 acres Initial Cost $ /acre$ /acre Irrigation Efficiency 90-95%70-85% Water Requirement gpm/acre gpm/acre Operating Pressure psi psi Energy Requirement (250-ft lift, ¼ mile supply line) 36 hp-hr/ac-in 48 hp-hr/ac-in

30 Gopher Damage on Subsurface Drip Tubing

31 Schematic of Subsurface Drip Irrigation (SDI) System Pump Station BackflowPreventionDevice Flowmeter ChemicalInjectionSystem Air & Vacuum Release Valve XX Pressure Gage XX Flush Valve XX DriplineLaterals Zones 1 and 2 Submain Flushline Filtration System x X Zone Valve Diagram courtesy of Kansas State University

32 Turbulent flow PVC emitter welded inside tubing Netafim Typhoon ® Drip Irrigation Tubing (Clear Demo Tubing) 16-mm diameter, seamless, 13-mil thick extruded PE tubing Emitter outlet

33 Netafim Typhoon ® Drip Irrigation Tubing Flap over emitter outlet: - prevents root intrusion - prevents blockage by mineral scale

34 30 in 60 in Typical Drip Tubing Installation for Row Crops 12 – 14 in Non Wheel- Track Row Wetting Pattern Drip Tubing 60-inch dripline spacing is satisfactory on silt loam & clay loam soils

35 Wetting Pattern of a Subsurface Drip Lateral Photo Courtesy of Kansas State University

36 Wider dripline spacings may not work. Photo Courtesy of Kansas State University

37 SDI System Maintenance Lateral flushing schedule (sediment)Lateral flushing schedule (sediment) Chlorine injection schedule (biological growths)Chlorine injection schedule (biological growths) Acid injection schedule (chemical precipitates & scaling)Acid injection schedule (chemical precipitates & scaling)

38 Salt Movement Under Irrigation with Saline Water Salt accumulation leached downward by successive water applications Salt accumulation leached radially outward from drip tubing Subsurface Drip Sprinkler/Flood

39 Small research plots during supply line installation

40 Plowing in drip tubing

41 Trenching across the drip tubing ends for PVC manifold installation

42 Drip tubing end after being sheared by the trencher

43 Components for Drip Lateral-Submain Connection 21/32” Hole in Submain Neoprene Grommet Polyethylene Barb Adapter 5/8” Polyethylene Supply Tube (Usually 2-3 ft long) Stainless Steel Wire Twist Tie 5/8” Drip Irrigation Tubing

44 Typical Drip Tubing Connection to Submain (1 ½ -inch Submains and Larger) Supply Submain or Flushing Manifold Neoprene Grommet Inserted in 21/32” hole in manifold Polyethylene Barb Adapter Inserted in Grommet 5/8” Polyethylene Supply Tubing 5/8” Drip Irrigation Tubing Stainless Steel Wire Twist Tie Identical connection on distal end for flushing manifold connection

45 Flush Risers on Distal End of Research Plots Ball Valve for Manual Flushing of Drip Laterals Air Vent to Release Trapped Air from Laterals

46 SDI Water Application Rates (inches/hour) (60-inch tubing spacing) 12 inches 18 inches 24 inches 0.16 gph gph gph gph Emitter Spacing Emitter Discharge


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