Sprinkler irrigation Sprinkler irrigation applies water to the irrigated area via a network of pressurised pipe with sprinkler heads. These systems can be low (1.5 - 2.5 2. 5 bar), medium (2.5 - 3.5 bar) or high (3.5 - 12 bar) pressure systems.
A sprinkler irrigation system has the following components: components: pump, filter, control valves, injection unit, a network of pipes with various sizes and emitters.The emmiter can be an agricultural sprinkler (impact sprinkler, full & part circle sprinklers), a heavy duty/big gun sprinkler (see pictures)
or a traveller equipment which can be centre pivot, lateral/linear move, hard or soft hose traveller (see pictures).
It is a flexible system that can be used to supply adequate moisture for plant growth as well as for frost control or crop cooling during heat waves. Chemigation and fertigation is also possible using this system.
Sprinkler systems can be used to irrigate almost any crops (row crops, broad acre crops) on a wide range of soil types and topography when application rates are matched to soil infiltration rate. The design of the sprinkler system
should minimise the potential for negative outcomes such as runoff, deep percolation, excessive evaporation, under application and excessive energy use, therefore the system design is very important.
They can be set systems or continuous move irrigation systems. systems .
1.Set System Irrigation Set systems can be periodic move or permanent systems. systems . Periodic move, are suited for areas requiring irrigation no more than every five to seven days. For frequent irrigations, permanent/set/fixed or continuously moving systems are more adoptable.
Sprinkler/overhead irrigation applies water to the irrigated area via a network of pressurised pipe with sprinkler heads. Set irrigation systems are using as an emitter, various vario us type of agricultural sprinklers (also called overhead over head irrigation). Based on the technical specifications they can be low capacity, medium size and heavy duty/large area sprinklers with one or two nozzle outlets. The sprinklers shoot jets of water into the air and spread it to the field in the form of rain drops in a circular pattern.
Sprinkler Type Low capacity Medium Full and Part circle Heavy duty/Large area
Q L/hr 400-2180 620-4080 286-1310 8500-110000
H bar 1-5 1.5-5.5 2.5-7 2-10
Nozzle mm 2.5-8 3.2-7 2.8-16 3.2-32
Wetted Diameter m 15-29 23-41 18-74 39-130
Based on the height of the water jet above the nozzle, they are divided into low angle (4-11º), or high angle (2030º). They are made of brass or high engineering plastics with internal or external threaded connections. They are installed vertically on small diameter riser pipes fitted on the laterals. The sprinkler spacing in the field is rectangular or triangular at distances not exceeding 60% or their diameter coverage (see pictures).
Rectangular
Triangular
The manufacturer/supplier brochures usually are showing the sprinkler's: nozzle size (mm), operation pressure (bar or kPa), discharge/flow (L/hr or m 3 /hr), the radius or the diameter of the coverage (m) and the
precipitation/application rate (mm/hr) at different spacing (triangle or rectangular). Also the recommended/optimum values are highlighted. me sh. Filtration requirements are necessary and should be about 20 mesh. It is a flexible system that can be used to supply adequate moisture for plant growth as well as for frost control or crop cooling during heat waves. In historical order, the Hand Move Systems were the first sprinkler systems (usually portable aluminium pipes). To minimise the labour, when shifting the pipes, and for better management, the aluminium pipes were attached to wheels or skids and moved across as one long pipeline on wheels. These were then called c alled Side Roll Systems. Systems. Because they were still labour intensive and hard to manage the movement of the pipes after irri gation, the permanent or solid sets/fixed sprinkler systems came along. In these systems the main lines and the submains have been buried and only the sprinklers wi th the risers were visible. Set systems have their advantages and disadvantages.
Advantages Provides good control of water application. Can be automated to save labour and energy. Pesticides and fertilizers can also be applied. Can be used for frost protection and for cooling. Has the ability to keep soil soft for emerging seedlings with frequent, short irrigation. Promotes rapid germination and crop establishment. With proper drainage can be used efficiently to flush accumulated salts down the soil profile.
Disadvantages. High capital cost, therefore they are used for irrigating high value crops. Distribution uniformity can deteriorate over time. It is a wind sensitive system, therefore the wind velocity should be taken into consideration when establishing the spacing between the sprinklers. May create a humid environment in the crop canopy which can can lead to disease. Can cause crop damage where saline irrigation wat er is applied.
1.1 Hand Move - Sprinkler Irrigation System Hand move sprinkler systems are a series of light weight pipeline (aluminium, plastic or layflat) sections that are moved manually from one zone to the other (see pictures).
Hand move sprinkler irrigation systems are normally the lowest cost sprinkler systems which offer growers flexibility and are the easiest systems to maintain. They are very labour intensive, therefore, are usually found in areas where man power is abundant or the labour cost is low.
In a typical hand move sprinkler irrigation system a mainline is installed from the pump to the field where a sub main breaks the field into small blocks. The sub main has a series of hydrants with take-off valves to provide water to the lateral. The mainlines can be either aluminum above ground or buried PVC. The sub main and laterals are aluminium pipes with couplers and fittings made of aluminum or galvanized steel. The couples and fittings (because of the gaskets) allow the pipes to be easily drained, un-coupled, moved and re-coupled.
After a section of the field has been irrigated, the hydrants are closed and the laterals are drained and carried to the next position.
Impact sprinklers (more than one on a rigid aluminium or PVC pipe) or big volume/heavy duty - also called large area sprinklers/guns - are equally spaced along the lateral lines. The sprinklers are mounted on risers.
Alternation in riser heights, spacing of sprinklers/laterals and water application rates make these systems suitable for almost any crop, except to tall growing field crops - due to difficulty in repositioning laterals. The flexibility of the hand move sprinklers will adapt to oddly shaped fields, to any variety of crops and to any soil conditions.
Power requirement is based on the sprinkler t ype (low, medium or high pressure).
Careful design is needed to match the sprinkler spacing, application rate and the infiltration rate of the soil. Efficiency can range between 65-75 %. Turn-key price for a hand move sprinkler system would be around 2,100-3,900 AUD/ha.
1.2 Side Roll - Sprinkler System The side roll sprinkler system is a mechanically moved version of a hand move system with wheels mounted on the pipeline (see pictures).
It doesn't move while irrigating. Side roll is a set irrigation system that is moved from position to position between irrigation zones. The movement can be through dragging or by a driven unit (i.e. by a small fuel engine).
The Side roll sprinkler system is similar to the hand move system, it remains stationary while water is applied. Because they are stationary during water application, spacing between sprinklers and laterals is based on wind speed. When the desired depth has been applied, the system is moved by hand (hand move) or mechanically (side roll) to another section of the field.
Is designed to be used on crops like vegetables, potatoes, soy beans, forage crops, wheat, barley, etc. The side roll is limited to crops under 1 m in height. Can be used on any soil suitable for sprinkler irrigation (care should be taken on heavy clay).
It is best suited for level fields that are square or rectangular. Can be used on a single field or on side by side fields where the lateral can be moved directly from one field to the other.
The infrastructure of mainlines, submains and hydrants is identical to a hand move system. However, the portable lateral lines are replaced by the side roll.
A typical side roll can be 460 - 490 m in length and it operates along a mainline with hydrants spaced every 60 - 80 m.
The sprinklers are usually medium to heavy duty agricultural sprinklers.
1.3 Permanent/Solid Set or Fixed - Sprinkler System Permanent/solid set/fixed refer to a stationary sprinkler system (see pictures).
The permanent sprinkler system is designed for a specific field and crop. The system cost is higher than for the hand move system mainly because the installation cost is higher. Once the system is installed, the labour requirement is minimal.
Permanent or solid set systems are usually found in areas with high labour costs and high value crops.
In a typical permanent system, all mainlines, submains and laterals are buried and permanently installed. These pipe lines are most often rubber ring joined PVC pipes. Permanent or solid set systems typically use low output single or double nozzle impact sprinklers, full or part circle or can have heavy duty/ big gun sprinklers for large areas (see pictures).
Individual blocks, or irrigation zones are isolated by manual or automatic valves. Most systems are irrigated in shifts. In some cases (using big guns) the system can be made semi-permanent by moving the big gun sprinkler or riser assembly to the next zone (see pictures).
Semi Permanent Big Guns
A permanent sprinkler irrigation system can be designed and installed for any field shape, crop (i.e. pastures, orchards, nurseries, potato, etc.) or application. Also, it is commonly used for frost protection and crop cooling.
The soil type, crop and cultural practices determine the sprinkler size and spacing. Generally, the spacing varies from 3.5 m x 3.5 m to 20 m x 20 m for low and medium sprinklers and from 36 m x 36 m to 72 m x 72 m for heavy duty/big guns, while application rates are between 4 mm/hr to 10 mm/hr and 10 mm/hr to 46 mm/hr.
The turn-key price for a solid set sprinkler system may be 5,800-7,500 AUD/ha based on the sprinkler type, spacing, filtration degree and automation requirement.
Application efficiency can be up to 70-85% with careful design, operation and management.
1.4 Hose Move/K-Line - Sprinkler Irrigation System Hose move sprinkler system is an improvement on the conventional piped hand moved systems and combines some features of semi-permanent installations with those of permanent ones.
In this system the sprinkler lateral lines are placed permanently at a wide spacing 55-60 m apart. The system consists of a series of small protective housings (pods), which contain and protect a sprinkler. The sprinklers, mounted on tripod stands are not fitted directly to the lateral pipes, but connected by low density polyethylene pipe (PE) 20-25 mm in diameter and up to 30 m in length. The small, flexible hose can be shifted in only minutes by a four wheeled motorbike by simply driving across the paddock (see pictu res).
The hoses with the sprinklers can be moved laterally on either side to cover a number of lateral positions. The sprinklers are low to medium pressure.
It is a system with low capital cost, easy installation and easy shifting suitable for all types of terrain. They are usually used for pasture irrigation on undulating/hilly topography.
Capital cost can vary between 2,200-2,800 AUD/ha and the system can provide 50-60% efficiency.
2. Continuous System 2.1 Centre Pivot - General Description The Centre Pivot system represents one of the most efficient and cost effective technologies of broad-acre irrigation available today (see pictures).
Also, it's the most suitable irrigation equipment for effluent irrigation. Provides a uniform depth of water application of the entire field (see picture).
Centre Pivot - Uniformity
Applies water, under low pressure, from a continuously moving lateral pipe supported by a series of towers/spans which do not require connecting or disconnecting to water mainlines. The lateral is supported by towers and cables or trusses which move on wheel track or skid support units.
Water is delivered to the pivot point usually through buried mainline pipe. The water enters the system at the pivot point (see picture).
Centre Pivot - Centre Point
The towers/spans are self-propelled so that the lateral rotates around a fixed pivot point in the centre of the irrigated circle. One pass/revolution time can range from a half a day to many days, based on application rates. This system can irrigate from 10-310 ha at pressures ranging from 25-65 Psi (1.7-4.5 bar). The longer the pivot, the larger the area covered and the lower the costs per hectare. The water application rate is increased with distance from the pivot to deliver an even application rate. The slower the pivot irrigates a circle, the more water is applied.
The centre pivot is kept in a straight line as it moves around the pivot point by an alignment system that speeds up or reduces speed or starts and stops movement of the towers as required to maintain alignment. If the alignment system fails and support units get too far out of alignment, a safety device automatically shuts down the entire centre pivot.
Because the centre pivot irrigates a circle, it leaves the corner of the field unirrigated, unless additions of special equipment i.e. end gun sprinkler (see picture)
Centre Pivot - End Gun
or corner swing arm (see picture)
are made to the system. The control panel, fertilizer injection equipment are located at the pivot point.
2.2 Centre Pivot - System Components Water Source can be a river, a channel, a hydrant or a bore hole. Also, it is the perfect solution for the untreated or treated waste water disposal (especially used in dairy farms). Water Supply System - The mainline can be PVC or PE, 100-150-200-225-250 mm in diameter, portable or buried to get the water to the centre pivot base. Power Requirement Power units for propelling a centre pivot are: Hydraulic water or oil drive - which can be a piston or rotary Electric motor drive, Mechanical or cable drive Air pressure drive The electric centre pivots require three-phase power in 380 - 415 V. Also, outlets for 110 or 220 V power should be installed at the pivot point for use with chemical injection equipment or for power tools for repairs.
Pumping System - Usually mid size pumps, from 1500-2500 L/min, are used to operate the entire pivot at once. Only low to moderate pressure is required. The pump can be diesel or electric, single or multiple stage or multiple pumps operating in series or parallel. Filtration Method - Mechanical: media or screen filtration is required, based on the water quality and sprinkler nozzle sizes.
Equipment Description The centre pivot can be as short as a single span to almost any length. The lateral pipe is supported about 3 m above the ground by a truss network. The lateral pipes are typically 6 5/8", chromium nickel, fully galvanized, poly lined or epoxy coated (see pictures).
Individual span/tower lengths range from 35-64 m. Pivot lengths typically range from 152-1000 m (irrigating up to 285-310 ha). The pivot lengths can be increased with overhangs from 2-28 m or with end guns (see picture), at the end of the span or overhang. The end guns need a booster pump before the gun to improve end gun performance. Based on the flow of the gun, the booster pumps can be 2-5-7.5 HP (1.9-2.4-3.6 bar).
The centre pivots can also be equipped with corner irrigation machines (see pictures). The corner machine takes care of the corners which cannot be reached by the centre pivots themselves. The corner pivot equipment consist of an extra tower that folds back along the main centre pivot lateral pipeline. It is activated by controls when the beginning of the missing corner is reached. When the system approaches a corner to be irrigated, the corner attachment swings out and the main lateral slows down. As the system exits the corner, the corner attachment swings back into position behind the main system. The corner pivot can irrigate another 6-9 ha. It is a really expensive unit of the Centre Pivot, there fore should be used irrigating real high value crops.
Depending on the speed of rotation of the pivot 5-25 mm of water can be applied in a single pass/revolution. To ensure uniform water application even on hilly or rolling terrain the sprayers are equipped with pressure regulators (see pictures).
If there is a variation of 10% or more due to field elevation, pressure regulators are recommended.
The centre pivot can be fixed pivot, skid tow, 2 or 4 wheel E-Z tow pivot (see picture).
On towable pivot machines, wheels can be rotated 90 0 for moving the machine from one field to another (see picture)
Towable pivots can be
pivots that are towed one or two times per season - this system would normally have a skid type pivot point pivots that are towed one or more times per week - this system is equipped with two or four wheeled centre pivot point
The fixed pivot is on reinforced concrete slab with cast in stone bolts for simple tightening of centre tower. The size of the slab can be 3.5 m x 3.5 m or 4.2 m x 4.2 m (see picture).
To find out more about other specifications (span dimension, pipes, truss braces/rods, tower weights and couplings, alignment control, tower legs, tower switchbox, tower structure, wheel gearbox, wheel and centre drive gearbox, drive shaft, tyres and rims), please visit each manufacturer's website on the Links page
www.2ie.com www.bauer-online.com www.centrepivot.com.au www.ibinternational.com.au
www.irrifrance.com www.irrigationindustries.com.au www.reinke.com www.rodneyind.com.au www.trailco.com.au www.valmont.com www.zimmatic.com
Sprinkler Packages
Pivots are fitted with various sprinkler packages, mounted on the top of the span or on drop-tubes (droplets), which can be galvanized or PVC or pol yethylene tubes, to accommodate crop, wind and field conditions. A sprinkler package is designed for a specific operating pressure, which is usually specified at the pivot point. Sprinkler arrangements/types (see pictures):
Old set up
1. Small agricultural/ impact sprinklers near the pivot point, medium sized near the middle of the lateral and large type sprinklers at the outer end of the lateral.
2. All medium size agricultural/impact sprinklers wit h a variation in nozzle sizes and sprinkler spacing along the lateral with the smallest nozzles at the outer end of the lateral. New set up
1. Low pressure spray sprinklers with fixed or rotating pad, equipped with pressure regulators (see picture)
(new generation-Nelson). There are four different types: Rotators, Spinners, Nutators and Sprayers (see picture).
2. Dual sprinkler setup with dual nozzle system (see picture),
allowing quick and accurate changes of system flow rate during germination and later stages of the crop's growth. All spray nozzles are coloured to distingui sh nozzle sizes. There are specific nozzles for waste water applications.
The sprayers can have pressure regulators (see picture) in order to fix a varying inlet pressure to a set outlet pressure, regardless of changes in the system pressure due to hydraulic conditions and to improve application uniformity (5 - 50 psi). The pivot sprinkler pressures are often set at 20 psi (1.38 bar).
Today's sprinkler packages offer better water management, fertiliser application and/or pesticide control. Selecting the right application package will reduce energy cost, save water, increase productivity and profitability.
Required Pressure - The system operates at a relatively low pressure 25-65 psi (1.7 - 4.5 bar).
Automatic Control System Mechanical or programmable control panels can be used (see picture).
Mobil management technology can also be incorporated. This allows control panels to be accessed and changed from anywhere in the world via: telemetry system, business band radio, mobile phone or direct phone line (see picture).
Online control system is available where several centre pivots can be linked up and controlled from the office via computer (see picture).
Safety devices present on the system stop the machine automatically whenever there is any malfunctioning. Usually the outside tower controls the speed of the system. A system of alignment controls, keeps the other towers inline between the end tower and the pivot point.
Wind speed and rain gauge can be mounted to stop the system if there is wind or rain. Also, soil moisture sensors can be hooked up to the control panel to stop and start irrigation based on the actual soil moisture.
A software can control and operate up to 32 pivot systems
Topography The system can handle rough terrain and slopes up to 30%.
Fertigation/Chemigation It is possible to distribute chemicals/fertilisers along the centre pivot, which can decrease cost and improve flexibility.
Application Efficiency - Under normal operation/management and maintenance the application efficiency can be up to 85%-95%.
2.3 Centre Pivot - Crops/Crop Planting Pattern Centre pivots are adaptable to most of the field crops (pasture, wheat, barley, corn, cotton, forage sorghum, oats, soybeans, sugar cane, etc) and vegetables (asparagus, beans, broccoli, carrots, lettuce, onions, potatoes, tomatoes, cucumbers, watermelons, etc) regardless of the height of t he crop (see pictures). Suitable for row planting or broad acre.
2.4 Centre Pivot - Maintenance Yearly Check air pressure in all tyres. Drain any water from gear boxes and refill with proper oil. Grease the pivot swivel. Check to ensure all drive shafts and shields are in place. Check sand trap to make sure sand is not buil ding up. Flush the system if it is necessary.
Pre-Season Check all sprinklers/nozzles at the start up time to ensure that they are spaying properly, ensure rotation. Ensure equipment is properly grounded. Check the structure and the drive units Check the oil level in the gearboxes Check depth of wheel tracks Check the functions of the controller
End of Season Drain the pivot and all the water connections to the pivot. Periodical After the first year of operation, drain and replace the oil from all w heel drive gear boxes and centre drive wheel boxes. Change oil in the gearboxes at least every third year under conditions. For machines operating more then 1000 hours a year, consider changing oil every year. Routinely check bolts for tightness and review the condition of gearbox seals.
2.5 Low Energy Precision Application (LEPA) A Low Energy Precision Application (LEPA) system is a Centre Pivot or a Lateral/Linear Irrigator with low energy requirements that eliminates drift and does not water on foliage. As a sprinkler package, a LEPA can be equipped:
with bubblers with very high application rate eliminating the misting and reducing soil erosion. Working pressure 615 psi (0.40 - 1.00 bar) (see picture) or
furrow drag socks minimising erosion to furrow blocks (see picture).
The sprinklers are suspended on drop tubes (see picture)
at a height of 0.30 to 0.90 m above the soil surface. Crop rows are planted to follow the circular path of the centre pivot system and alternate furrows are irrigated. Some LEPA applicators can be converted to spray heads (see picture)
that have wetted areas of 3-7.5 m in diameter. The LEPA systems have high application rates that usually exceed the water infiltration rate of the soil. Basin tillage is required. Wind drift and spray evaporation are eliminated, therefore high application efficiencies 90-95% can be achieved.
Unsuitable for slopes and undulating terrain.
2.6 Centre Pivot - Operation/Management Hints Check pressure, make sure adequate pressure is available - if not, the Centre Pivot will not irrigate uniformly. It is suggested moving the pivot to the highest elevation point and placing an accurate gauge on the end of the machine.
Monitor the pressure each irrigation season. If the pressure begins to decrease, this can be a sign of problems with the pumping equipment or other problems in the water delivery system.
If wheel track problems are anticipated or become an issue, use different tyre sizes or products that wrap around the tyres and spread the weight of the pivot (see pictures).
Other options to avoid wheel track issues, initially design the machine with shorter span lengths to reduce the weight on the tyres.
To keep water away from the wheel tracks, using boom backs or use 180 o sprinklers around the wheels (see pictures).
The soil profile should be near field capacity before peak water use to avoid plant stress. If irrigation is started too late, meaning subsurface moisture becomes depleted, to catch up will cause to force the speed of the system and to run the Centre Pivot every day. In this case the application rate will be really small, most of the water will be evaporated during irrigation and the wheel tracks will be damaged, as well. It is important to monitor the soil moisture and to set the right application rate (via speed) according to the current soil moisture. The soil moisture sensor can be hooked up to the Centre Pivot's control panel, which can start or stop the irrigation.
Irrigation should occur overnight, when wind drift and evaporation losses are minimal.
2.7 Centre Pivot - Advantages Labour savings: the continuous movement of the system reduces the labour requirement of irrigation and increases the number of irrigated area which can be covered at a given pumping rate. Pivots eliminate the cost of: laying pipes/tubes, moving pipes/tubes, checking gates/tubes, walking rows, ditching/damming, land levelling and multiple tillage operations. Once the pivot is set up, there is no physical labour required. One person can operate the whole system. Crop water use efficiency increased by 50%-75%. Water savings compared to any surface irrigation up to 4570%. Increased yields compared to surface irrigation up to 5%-25%. Double cropping it is possible. Planting into the crop residue following harvest allows a second autumn/winter crop. The practice shows 3 crop/2 year rotation, i.e. corn - wheat - soybean. Reduces water logging because a wide selection of nozzle types are available, so the system can match the infiltration rate of the soil. The system is a low pressure system, therefore low pumping energy is required. Can apply different application rates, during a revolution (having different crops or various soil types) during one revolution with improved water application uniformity. Centre pivots are suitable for chemigation/fertigation. Pivots have a relatively low capital cost per hectare.
2.8 Centre Pivot - Disadvantages Not recommended for heavy soils with low infiltration rates . Wheel track issues, which can be handled . Difficult to transfer from field to field but not impossible. Designed to irrigate in a circle and not suitable for irrigation of odd shape fields.
3. Lateral/Linear 3.1 General Description Linear or lateral move systems are similar to centre pivot systems, except that the towers move in a continuous straight path across a rectangular field (see pictures).
The system moves (back and forth) in one straight line to cover either a square, a long rectangular or L shaped fields (see picture).
Linear systems become economical when the field length is 1.5 to 3 times the width. Water is fed into one end of the linear move system by either hydrants or directly from a canal with a pump on the end of the line. Generally they have their own power source (i.e. motorized pump) mounted at the main drive tower. They can be towable too similar to the centre pivots. Wheels can be rotated by 90º for moving the machine from one field to another (see picture).
The flexi hose type needs a relatively flat, uniform, dry road for the hose pull cart for proper guidance and traction. Hose sizes are between 75 -150 mm and the lengths are between 100-260 m. The flows are ranging from 70 - 260 m3 /h. The ditch/channel type can use an earth or concrete ditch or channel. The earth ditch should have a top width minimum 3.30 m, batter angle 45 0 and the minimum base with of 0.90 m. Depth should be a minimum 1.20 m. The concrete ditch should have a top width minimum 2.20 m, batter angle 45 0 and the minimum base with of 0.30 m. Depth should be a minimum 0.75-0.90 m.
In order to follow the right track, a straight V shaped trench/furrow, buried electric cable or above ground guidance cable is needed. All three types should be surveyed perfectly from end to end. Wheel tracks must be straight and a maximum depth controlled (see pictures).
The alignment of the tower is really essential, because there is no fixed point, the entire system will stay off line if the alignment is not perfect.
Sudden or extreme terrain changes should be avoided because they can cause excessive compression or tension and guidance irregularity. Linear systems are more adaptable to lower pressures on heavier soils. Sandy soils also suited to these systems.
3.2 System Components Water Source - can be a river, a channel, a hydrant or a bore hole. Water Supply System Where the water supply is limited (for small areas) the hose fed system is more adequate and where larger quantities of water are available the dit ch/channel fed linear systems are more adaptable. The linear move system can be connected to: a pressurized pipeline hooked up to a hydrant with a flexible hose. This system can move t wice the length of the flexible feeder hose before the system will stop automatically (see pictures).
the system can also pump water from a ditch/channel, fed by an on-bored pump system. Can be end fed or centre fed ditch/channel. A ditch fed is for large irrigation systems up to 1000 m 3 /h with a system length up to 1200 m (see pictures).
Power Source - A power package (engine, pump and generator) is located on the linear system to drive the system and pressurise the water if needed. Pumping System - If it is a hose fed linear system hooked up to hydrants, low to medium pumps are required. Filtration Method - Based on the quality of the water, a large area intake screen filter or media filtration is required. Equipment Description - Similar to the centre pivot system, except that the lateral/linear system moves in a continuous straight path, in one straight line, therefore the center point does not exist. Sprinkler Packages - Similar to the centre pivot sprinkler packages, except the sprinklers are the same size along the length of the system. Required Pressure - Similar to the centre pivots. Automatic Control System - Similar to the centre pivots. Topography - Linear systems are designed to operate on fields with general level characteristics or very gradual slope. Maximum slope around 5%.
Fertigation/Chemigation - It is possible as with the centre pivots. Application Efficiency - Under normal operation/management and maintenance can be up to 90%-95%.
3.3 Crops/Crop Planting Pattern - Similar to centre pivots.
3.4 Maintenance - In addition to the centre pivots, maintenance is needed on control/guiding systems and on the motor used to run the on board generator, pump and filtration system as per the manufacturer's recommendation, to minimise system failures and damage to components.
3.5 Advantages Linear systems advantages are similar to the centre pivots': The continuous movement of the system reduces the labour requirement and increases the number of hectares that can be covered at a given pumping rate, but labour requirement is higher than for the centre pivots. Efficient application of water 90-95%. Increase yield and quality. Double cropping is possible. Reduces water logging, because of the wide selection of nozzle types, the system can be matched to the soil's infiltration rate. Low pumping energy requirement. Suitable for chemigation/fertigation. Irrigate the entire field including the corners. Relatively low capital cost per hectare.
3.6 Disadvantages More difficult to operate as centre pivots Capital cost of the machine is higher than of the centre pivots' because a drive cart is required with an on-board generator, engine or pump, but the overall $/ha -after installation- cost can be less. Deeper ruts can be created when the wheels travel over wetted, fine textured soil.
3.7 Operation/Management Hints Similar as to operate a centre pivot. When the system completes a pass across the field, the machine must return to the starting point. One way to operate is to apply less water on each pass and operate the system back and forth as needed to meet water demand, irrigating both ways. A second method of operating is to irrigate in one direction, and run the unit back dry to the starting point to be ready for the next irrigation.
4. Hard/Soft Hose/Booms Travellers 4.1General Description The Traveller is a continuous move irrigation system that uses a big gun sprinkler or a boom mounted on a wheel or trailer, fed by a flexible hose or by a soft hose, which is on a reel or on a spoon . The hose is run-out and during operation, the stationary hose reel rotates rolling the hard hose back onto the reel, puling the sprinkler/boom back to the machine - Hard Hose/Boom Traveller - or the four wheel stance with the sprinkler is moving back on a stainless steel or galvanized cable - Soft Hose Traveller -. They are powered track or wheeled vehicles that tow a high pressure flexible hose connected to the water supply main pipeline. Based of the type of the flexible hose, they are called Hard Hose - hose tow - or Soft Hose Travellers - cable tow - (HHT or SHT).
The operating pressure can be between 3.5 - 13 bar. Manufacturer's catalogue usually shows the machine type, big gun/sprinkler type, nozzle sizes (mm), wetted width (m), flow rates (L/sec or m 3 /hr), pressure (bar), hose diameter (mm), hose length (mm), area irrigated per run (ha) and the possible application rates for 6 - 7.5 - 8 - 11 or 22 hours run.
With its medium to large droplets and application rates, varying from 10 - 15 - 20 - 25 - 30 - 35 - 40 - 50 - 60 mm,
the travellers are best suited to agricultural fields with coarse soils having high intake rates and to crops
providing good ground cover.
They are very popular and effective machines for irrigating pasture, fodder crops, vegetables and practically any field crops. They are not that expensive, easy to operate and move.
It is suitable for waste water applications, as well.
4.2 System Components Water Source - can be a river, a channel or a bore hole. Water Supply System - Mainline pipes usually buried PVC pipes at 100-150-200 mm diameter, ending with a hydrant with a quick coupling connection. Power Requirements - The self-propelled travellers use either a water turbine, water piston or internal combustion engine mounted on the reel/spool to power a winch and cable to tow the vehicle. Pumping System - Simple or multi stage pumps with a pressure rate between 3.5-13 bar, based on the size of the machine. Filtration Method - Filtration is not necessarily required, because of the big nozzle sizes (14-37.5 mm). In the case of the boom system a sand or screen filtration is required based on the nozzle sizes of the sprinklers. An inline, self cleaning filter is usually fitted to each machine to protect the valve and the drive unit.
4.3 Equipment Description Hard Hose Traveller - the big gun sprinkler is mounted on a wheel cart connected to a high density polyethylene (PE) hose ranging from 40 -140 mm diameter (see pictures),
with the length ranging from 150 m to 750 m. The hose reel is stationary during an irrigation run. The irrigation water, under pressure, drives a turbine which turns the drum that rewinds the hose. The drum slowly rewinds the hose, the gun cart is pulled towards the main unit and irrigates a rectangular shape while being pulled. They are usually marked like this: 35 65 - 270 - where 35 is the machine type, 65 is the PE pipe diameter and 270 is the PE pipe length. A typical big gun sprinkler discharges 14-143 m3 /hr with the wetted diameter of 50-140 m at a connecting pressure between 3.5 to 13 bar. The application rate can be anything between 8 - 60 mm. To cover all possible
scenarios in terms of the irrigated area, flow, pressure and application rate each manufacturer has a huge range of HHT (35 to 40 various size of HHT per manufacturer) based on the combination of the hose diameter, hose length and sprinkler type.
The speed of rewind determines the speed of the gun while determines the water application rate. Slow pull high application rate, fast pull - low application rate.
Soft Hose Traveller irrigators are similar to the hard hose ones but the big gun sprinkler attached to the machine and the machine is wound along a steel cable (see pictures).
The cable is anchored at the end of the traveller run and winds up on a cart mounted winch. The winch is powered by either an auxiliary engine or water turbine.
Usually are using similar big gun sprinklers with a discharge between 35 - 154 m 3 /hr with the wetted diameter of 81 - 140 m at a connecting pressure between 3.5 - 8 bar.
Boom irrigators are like a combination of a linear move sprinkler boom pulled in by the drum and hose reel. There are generally low pressure machines 1 to 4 bar, with a discharge of 12 - 82 m 3 /hr. Spray booms apply a fine mist with an application rate of 5 - 40 mm . The boom lengths can be from 18 - 80 m and the hose lengths from 200 - 400 m (see pictures).
There are used on row crops, mostly vegetables and short fodder crops such as lucerne.
The travellers are hooked up to a medium to high pressure piping network with hydrants. Normal spacing between the hydrants/runs can be 50 - 70 % of the sprinkler's wetted diameter. The exact spacing depends on the combination of sprinkler performance, field dimensions and wind conditions.
Once the traveller is in operation, it can irrigate unattended an area equal to the length of the hose by the wetted diameter of the gun. This can be an area between 1.40 - 6.50 ha per run with HHT and 1.60 - 3.50 ha per run with SHT and 1.5 - 8.64 ha/run with Booms.
Sprinklers and Booms - The big gun sprinklers can be with single or double nozzle with a flow rate range of 14-143 m3 /hr with the hose diameter of 40-140 mm at a connecting pressure ranging between 3.5 to 13 bar (see pictures).
Booms can have a choice of pressure regulated spray jets, rotators or spinners and drop pipes. Also can be mounted with end guns (see picture).
Spray booms apply a particularly fine mist and operating on a low pressure (see picture).
Required Pressure - Connecting pressure at the hydrant for Hard Hose Travellers is 3.5 - 13 bar, for Soft Hose Travellers is 3.5 - 8 bar and for Boom Irrigators is 1 - 4 bar. Automatic Control System The HHT can be equipped with automatic control panels, which are easy to operate. Major features: speed settings, lay down PE pipe length, adjustable precision pressure switch, pipe guide for laying down the PE pipe, automatic start and stop, etc
Topography - The traveller system can be used on topography ranging from level to rolling and irregular. It can be used in fields that have some obstacles, such as power line poles, trees or buildings. Can be used on different odd shaped fields and most soil types. Application Efficiency - Under proper operation and management the application efficiency can be up to 60 75% for HHT and SHT and up to 75 - 80% for the Booms. Crops/Crop Planting Pattern - The traveller machines are used on row or broad acre crops like vegetables as well as turf, pasture, maize, lucerne, potatoes, pineapple, etc
4.4 Advantages It is a quick irrigation equipment for versatility - the travellers can irrigate a very wide range of crops and operate well on extremely undulating terrain. Low labour requirement - several travellers can easily be operated by one man and the labour consist mostly on driving a tractor and moving the eq uipment form one hydrant to the other one. Set up time is minimum, at the end of the irrigation cycle most units automatically disengage the drive unit and some disconnect from the water source, allowing unattended operation. One machine can irrigate more than 10 ha/day, applying 2 0-25 mm of water. One reel can operate up to 6.5 ha in a single pull/run. High distribution uniformity (at the optimum operation level) - the continuous movement of the traveller provides a high uniformity of water application. Adaptable to almost any shaped and sized field and can operate around obstructions. Portable - easy to transfer from field to field or farm to farm. Application rate can be adjusted for variability in soil moisture conditions in the field, even during one run. Easy to use, operate and maintain. Can irrigate waste water and animal manure.
4.5 Disadvantages
Travellers have a medium to high capital cost. There are high pressure losses to the reel hose, therefore, high pressure is required 3.5 - 13 bar. This is why the system is relatively expensive to operate. Cannot be used for frost protection. These systems can cause water runoff and soil erosion if not operated properly. Downtime while moving the system between the hydrants. Not suitable for chemigation/fertigation. Not applicable on heavy texture soils that have very low water intake/infiltration rates. High winds will distort sprinkler application pattern and reduce the uniformity of the application. Large droplets (especially if pressure is too low) may damage crop and destroy the structure of surface soil particles, which can reduce the soil infiltration rate significantly and cause runoff.
