Overlap of multiple irrigations
3-D Uniformity Simulation
3-D Uniformity simulation
© Irrigation Association
Main causes of non- uniformity Nozzles installed in the wrong order Damaged or plugged sprinklers Damaged sprinkler replaced with whatever is in the truck
Trash in the regulator © Irrigation Association
Trash on/in the sprinkler © Irrigation Association
Replaced by anything in the truck © Irrigation Association
Lower uniformity costs more pumping cost and reduced yields
Controlling Runoff
FACTORS AFFECTING RUNOFF 1. SYSTEM CAPACITY - GALLONS/MINUTE PER ACRE 780 GPM / 130 ACRES = 6 GPM/ACRE 2. DEPTH OF APPLICATION PER REVOLUTION - INCHES 3. SPRINKLER PACKAGE - SPRAY, IMPACT, LEPA 4. SOIL SURFACE CONDITIONS - AMOUNT OF WATER THE SOIL SURFACE WILL HOLD
POTENTIAL RUNOFF UNDER CENTER PIVOTS PEAK APPLICATION RATE TIME, hours RATES, inches / hour TIME OF WETTING
POTENTIAL RUNOFF UNDER CENTER PIVOTS 900 GPM 130 ACRES 50 FT WETTED DIAMETER 1 INCH APPLICATION APPLICATION RATE INFILTRATION RATE TIME, hours RATES, inches / hour
POTENTIAL RUNOFF UNDER CENTER PIVOTS POTENTIAL RUNOFF TIME, hours RATES, inches / hour 900 GPM 130 ACRES 50 FT WETTED DIAMETER 1 INCH APPLICATION SURFACE STORAGE
SURFACE STORAGE SOIL DEPRESSIONS STORE WATER LESS STORAGE ON STEEP SLOPES SOIL
EFFECT OF SPRINKLER PACKAGES ON APPLICATION RATE TIME, hours APPLICATION RATE, inch/hr 900 gpm 1300 ft distance 1 inch applic. 130 acres PACKAGES 40 ft Degree Sprays 70 ft - Low Pressure 120 ft - Medium Pressure 160 ft - High Pressure
TIME OF APPLICATION, hours CHANGE OF APPLICATION RATE ALONG A PIVOT feet 650 feet 975 feet APPLICATION RATE, inches/hour
EFFECT OF APPLICATION DEPTH ON RUNOFF SCS INTAKE SOIL 0.8 in 1.2 in1.6 in 2.4 in TIME, hr RATES, inches / hour APPLICATION DEPTH
ft 40 ft 60 ft 100 ft 120 ft WETTED DIAMETER: EFFECT OF CAPACITY ON PEAK APPLICATION RATE SYSTEM CAPACITY, gpm / acre PEAK APPLICATION RATE, IN/HR 1300 ft from pivot
Hill side erosion from pivot
HOW TO REDUCE RUNOFF? 1. REDUCE SYSTEM CAPACITY - irrigate more hours per year 2. REDUCE APPLICATION DEPTH - make more revolutions per year 3. CHANGE SPRINKLER PACKAGE - increase wetted radius - may need higher pressure 4. INCREASE SURFACE STORAGE - extra tillage - make changes to pump - increase chances of getting behind
Nozzle Layout
Offsetting Drops
Offsets of offsetting drops
Spray booms on outer spans
Boom backs on pivot
Boom backs behind towers
Impact of booms on application rate
Methods of increasing Surface Storage Basin Tillage Dammer-diker Subsoiler Field cultivator Rough cloddy ground (slope dependent) Organic residue
Dam-Dikker
Basin/ reservoir tillage
LEPA System
Surface storage from crop residue
© Irrigation Association
Let’s go to our manuals
Pressure Regulation
Determine the Need for Regulators Impacts of elevation Impacts of corner systems and guns Cv and hysteresis
Determine the Need for Regulators, cont. Minimum pressure losses through regulators To regulate or not to regulate
Pressure Regulator FLOW SPRING
Practice example A system is on a field where elevation changes by 10 feet as the lateral travels around the pivot. The water surface in the ground water well changes by 10 feet over the course of the irrigation season, and an end-gun, when turned on, causes an increase in friction along the lateral of 2 feet. If the design pressure of the system is 20 psi, are pressure regulators are recommended? If the design pressure of the system is 50 psi?
Determine the Need for End Guns Does the system have regulators? Will the gun be intermittent? Is there chemigation?
Determine the Need for End Guns, cont. Soil intake rate concerns Base pressure of the pivot Uniformity and economics
Size the End Gun Capacity Sprinkler arc Pressure, booster pump Steep vs. flat curves of main pump
Center Pivots + End Gun Inexpensive coverage of field area beyond pivot length 80 to 100 psi needed for good coverage. Booster pump often used to increase pressure at the end gun (2,5 or 7 hp) Impact driven Gear driven
End gun with booster on end of lateral and a large sprinkler head each is operated separately
© Irrigation Association
Reinke End Gun
Corner Systems: Are they needed?
Center Pivots + Cornering System Allows system length to expand by up to 200’ with a single arm or 350’ in a Z configuration.
Corner arms 1520’ Added 53 acre if used 100% of time, 48 acre if used 90% of time 35 acre if used 66% of time. 18 acre if used 33% of time. 35 additional acres 8 acres 165’ 330 ’ 495’ 660 ’ 825’ 990’ 1320’ 1155’ 2 acres 18 acres 31 acres 49 acres 71 acres 96 acres 126acres
Double Action Corner
© Irrigation Association
Let’s go to our manuals again
End gun on/off switch
Kill switch
Temperature sensor
Surge proctor
Management Monitoring and Controls Valley Pro2
Remote control
RadioLink PanelLink AuxiliaryLink BaseStation2
Wheel Tracks and rutting
Why are wheel ruts a problem? Can result in machines bogging and stopping, or even damaging the machine. When a tower stops, it gets out of alignment with the other towers, which causes the machine to shut down. Most manufacturers consider their warranty void where machines operate with ruts deeper than 4 inches
Wheel rutting can be minimized by : Keeping applied water off the wheel tracks; – Booms – Directional nozzles – Span pipe drains
Booms at towers
Directional sprays
Span Pipe Drains span pipe drain valves, are located at the lowest points on the span pipe. whenever the machine stops, much of the water in the span drains onto the wheel track Solution – Place a fitting over the valve and connect a hose to the fitting and fix to the truss rod several feet away to discharge water away from wheel.
Wheel rutting can be minimized by : Increasing the load-bearing strength of the soil along the wheel track lines; – PAM – Replace soil
PAM bags
Float
Wheel rutting can be minimized by : Reducing the pressure applied to the soil by the wheels. – Shorter spans – Larger Tires – Tracks, three wheels etc.
Tracks
Three wheels