Conventional flood irrigation practices have been inefficient for decades. A lot of water gets wasted in deep percolation and runoff. It doesn’t meet the water needs of crops. This has put immense pressure on groundwater resources over the years. The water tables are depleting at an alarming rate, calling for sustainable irrigation practices.
The center pivot irrigation system has emerged as a revolutionary technology to address this problem. It utilizes sprinklers placed on an overhead rotating boom that revolves around a central pivot and applies water slowly and evenly to the crops. As the boom moves, the sprinklers neatly cover a circular area of land in a time-saving and precise manner.
This method reduces water usage by around 30% and improves crop yield by 15% compared to flood irrigation. It ensures every drop of water counts toward nourishing the crops.
What is a Center Pivot Irrigation System?
A center pivot irrigation system, also commonly referred to simply as a pivot or center pivot, is a method of crop irrigation that circulates around a pivot point. As the term implies, the primary component is a large irrigation tower that is fixed in the center of the crop field.
Attached to this center pivot are a long pipeline, sprinklers, and drive equipment that cause the entire system to rotate around the tower in a circular pattern, irrigating the field as it goes.
A Brief History of Pivot Irrigation
The concept of center-pivot irrigation was invented in 1940 by farmer Frank Zybach. However, it wasn’t until 1952 that the first center pivot system was successfully designed and installed by engineer Robert Daugherty in Colorado.
Since then, center pivot technology has advanced significantly. Early systems were much smaller in span and relied on diesel motors to power their rotation.
Today, center pivots come in massive circular arcs with spans over 1,500 feet and can include a variety of drive types like electricity or solar power.
Center pivots rapidly gained popularity in the mid-20th century as a labor-efficient way to irrigate large circles of crops. Today, they are commonly used worldwide for watering crops like corn, soybeans, cotton and potatoes.
Parts of Center Pivot Irrigation System
Let’s closely examine the key components that make up these large-scale systems. Maintaining and replacing parts in the right manner is the key to the 20-year operational life of a pivot.
The Pivoting Tower
The tower is the fixed centerpiece of the whole system. It faces big structural demands. Towers are usually made of steel pipe or tubing. They can be solid, truss, or portal-style frames. The specific design depends on factors like soil conditions and required clearance heights.
Taller tower options include the truss tower framed with angled steel beams or the portal style with outward-leaning arches. These provide elevated pivots with adequate clearance to rotate above crops and obstacles without getting tangled or struck. Underground anchors secure the base in place against rotational forces.
The Water Distribution Pipeline
Attached to the top of the tower is the primary riser pipeline. This main water delivery conduit, usually constructed of heavy-duty steel, aluminum, or polypipe, extends out radially like the spoke of a wheel. At intervals along it, there are drop lines that lower sprinklers to the ideal application height above crops.
For extra-large pivots, the riser may be supported by intermediate towers placed every 1/4 to 1/3 of the total span length. The drop lines are attached to risers elevated above the field on drop tube assemblies or wye joints in the main pipeline. They can pivot around curves and corners while maintaining consistent sprinkler placement.
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Sprinkler Nozzle Assemblies
Reaching the outermost points of irrigation coverage are the sprinklers themselves. Based on the water flow needs, soil types and crops, a farmer can choose between impact, rotating, spray plate or other nozzle designs.
Likewise, nozzles may feature fixed, rotating or oscillating spray patterns. Proper spacing and sizing of sprinklers helps deliver an even distribution of droplets
Water Supply and Pump System
For a center pivot to operate, it requires a consistent and adequate supply of water delivered at sufficient pressure. Pivots need larger pump stations. They must meet higher demands than other irrigation methods.
The water source is usually a well on the farm. It taps into local aquifers or ponds. Raw water is gravity-fed or pumped into large storage tanks located near the pivot point.
They then pressurize the incoming water. They do this by pumping it up through the riser pipeline network. Motors range from 25 to 1000+ horsepower, depending on the system size and flow needs. Proper filtration removes sediment that could clog sprinklers.
Backflow prevention valves protect the water source from potential contamination. Automated controls help regulate pumping cycles and prevent over-pressurization issues. Access ports allow for flushing, maintenance and water sampling.
Keeping the pump station efficient is key. Even small pressure losses along long pipelines impact water uniformity at the far corners of large pivots.
Electrical and Control Systems
Computerized controllers house the “brain” of a center pivot system. Programmable logic units automate movement, coordination of sprinklers and monitoring of functions.
Wiring harnesses run the length of drop tubes to power motors, sensors and monitors along the riser mainline. These are protected by electrical tubing and conduit. Solar panels may supplement grid power for certain components.
GPS capabilities enable auto-stop at property boundaries. They also link with guidance systems for other farm machinery. Telematics allow remote access, alerts and troubleshooting via smartphones when issues arise. Data logging optimizes future irrigation management decisions.
Proper grounding and lightning/surge protection prevent damage during storms. Backup generators safeguard functionality during outages. Overall, these electrical and control systems are highly advanced technologies integral to modern precision agriculture operations.
How Does Pivot Irrigation Work?
Center pivot systems operate on a continuous rotation basis. As the pivoting tower remains stationary in the center, the primary pipeline is programmed by its control system to rotate slowly but consistently around it. This circular movement results in the entire system traversing across the crop field in a predictable watering pattern.
The rotation is powered by an electric, diesel, solar or other type of drive motor located either at the pivot point or at intervals along the riser pipeline. As the pipeline revolves, it guides the movement of the sprinklers above it in a coordinated fashion. Water is distributed to crops through impacted rotating sprinklers or spray heads spaced at regular intervals along the lateral lines.
Precise software controls the rotation speed and programmed stopping points to ensure complete and even coverage. Water is supplied to the pivot from a groundwater well, surface reservoir or municipal supply. The water enters at the pivot structure and is pressurized up elevated risers to the sprinklers by a large booster pump. Flow can be adjusted via valves according to conditions and crop needs.
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Benefits of Center Pivot Systems
Center pivots offer farmers several productive advantages over other methods of irrigation:
| Aspect | Description |
|---|---|
| Efficiency | Very little water is lost to evaporation, drift, or deep percolation due to the slow but continuous sprinkler movement and precise droplet application. |
| Labor Savings | Once initialized, center pivots require very little manual labor to operate compared to flood irrigation techniques. Controls allow remote operation and monitoring. |
| Large Coverage | With spans measuring upwards of 1,600 feet, a single pivot can irrigate multiple center-pivot circles of 130 acres or more in a given season. |
| Uniformity | The consistent rotational pattern delivers an even distribution of water across all parts of the circular field. Soil moisture and crop yields remain balanced. |
| Flexibility | Pivots can traverse most any circular or semi-circular field. Obstacles are simply avoided as the system moves around them. |
Choosing the Right center Pivot System
With such extensive capabilities, investing in a center pivot irrigation system requires evaluating specific property and field conditions to select optimized components and designs. Working with an experienced dealer is recommended for assessing needs and code compliance.
Field Size and Shape Requirements
Most standard pivots can cover circular areas of 40–130 acres. For irregularly shaped parcels, corner systems allow pivoting around at sharp angles. The minimum recommended diameter is about 1,320 feet to efficiently utilize the equipment.
Span Length Considerations
Longer spans increase coverage but require additional towers, stronger structures and larger pumps. Terrain variations may also necessitate multiple independent pivots with different radii.
Pipe Material Options
Galvanized steel pipe remains most common, but plastic options like polytetrafluoroethylene (PTFE) resist corrosion and are less prone to leaks over time. Aluminum also performs well in many climates.
Drive Systems
Electric drives afford simple controls but require nearby power sources. Hydraulic, diesel and wind systems function adequately in remote locations. New solar power alternatives minimize energy costs.
Tower and Sprinkler Package Selection
With a variety of sprinkler placement heights and full/half circles available, consult your soil report and crop plan to configure the optimal package.
Proper component choices matched to specific growing conditions help center pivots maximize both water efficiency and crop yields for many seasons. Needs will vary depending on the intended crops, soil composition and environmental factors unique to each farm.
Installing a center Pivot Irrigation System
Once components are selected, professional installation is recommended to ensure proper setup and performance. Expect installation costs to range from $15,000–25,000 for basic systems up to $100,000+ for extra-large pivots, depending on the size and required infrastructure. Allow 1-3 months of lead time for major pivots.
Land Preparation
Clearing trees and leveling low-lying areas may be necessary to provide adequate clearance and ensure uniform water distribution. Proper drainage is also important to prevent ponding.
Anchor System Installation
Deep pilings or concrete slabs anchor the unmoving center tower base. Underground cables are trenched out radially with pull boxes to connect to electrical controls.
Pipeline Installation
Starting from the tower hub, the heavyweight riser pipe is positioned in an expansive circle. Drop-line tubes are inserted at predetermined heights, guided by lasers. Curves are installed to navigate around obstacles.
Electrical Installation
Miles of wiring harnesses run through drop tubes to provide power to each sprinkler subsection. Weatherpack connectors join sections. Main transformers relay electricity from the grid.
Tower and Pipeline Assembly
Using crane equipment, the elevated riser tower is erected along with any required intermediary hubs or towers. The preassembled pipeline is slowly raised and linked together in a massive circle.
System Calibration
Sprinklers are set to the proper precipitation rates. Computer software is programmed with customized control schedules, speeds, watering times and safety parameters for the specific field geography.
Thorough testing ensures balanced coverage and that all components function as engineered before crops are planted under the new center pivot irrigation system. Reprogramming may be needed for changing conditions over the lifespan of the equipment.
Operating and Maintaining Pivots
Once installation is complete, properly operating and servicing the system helps maximize efficiency and the return on investment over 20+ years of use.
Daily System Checks
Brief inspections confirm no obstructions or leaks have developed. Controllers verify normal rotation and sprinkler patterns without issues. Pressure gauges are reviewed.
Preventive Maintenance Schedule
Regular lubrication of moving parts prevents premature wear. Gears and drive chains are tightened as needed. Leak tests use dye to find weakened pipe joints requiring repair clamps.
Filters and Nozzles
Clogged sprinkler screens or worn nozzles reduce precipitation rates and must be cleaned or replaced based on inspection. Pressure regulation valves are adjusted seasonally.
Winterization Process
Draining tanks and pipelines fully prevents damage from line freeze-ups in colder climates. Rodent proofing helps too. Storage indoors protects components from weathering.
Upgrades Over Time
New technologies in hardware, controls or sprinkler packages can boost productivity and crop yields. Replacing sections maintains good performance over the asset’s lifetime.
Monitoring alerts from software Catch problems early to minimize downtime. Proper care safeguards this sizable capital investment that forms the backbone of many modern farming operations.
Industry Resources for Pivot Owners
Center pivots make up much of the agricultural infrastructure. An industry has developed around its design, parts, installation, training, and support. These resources help producers maximize pivot performance.
Manufacturers, Dealers and Installers
Leading brands include Valmont, Lindsay, Zimmatic and Reinke, among others. Local authorized technicians maintain equipment and supply replacement parts on warranty.
Design and consulting Services
Registered professional engineers analyze soil surveys, rainfall patterns, and field dimensions. They use this information to make layouts and specs tailored to each property.
Training Courses and Certification Programs
The coursework educates operators and district staff. It covers best practices for safety, programming, and maintenance. Certifications demonstrate competency and qualifications.
Farm Irrigation Associations
Groups like the Irrigation Association advocate for the industry. They provide member benefits like newsletters and discounts. Regional chapters host educational seminars.
Government Agriculture Programs
State and federal water conservation programs offer rebates for adopting efficient irrigation technologies. Some assist with initial installation costs for qualifying farms.
Conferences and Trade Shows
Major annual events gather manufacturers, engineers, dealers, and producers. They come to showcase the latest innovations, exchange ideas, and make industry connections.
Relying on authorized experts yields the best returns from center-pivot investments. Coordinating with local businesses and regulatory groups further sustains agricultural operations for decades.
FAQs
How much do center pivots cost?
Base system costs range from $15,000–$50,000 for smaller spans up to $100,000+ for extra-large pivots over 1,000 feet. Installation typically adds thousands more.
What is the optimal pivot size for a field?
Pivots should cover circles at least 1,250 feet in diameter for efficiency. Fields under 90 acres usually require multiple pivots. Larger spans increase coverage but also cost.
How much water do pivots use?
Water application rates vary greatly depending on crop, soil, and climate factors. On average, center pivots disburse 0.1–0.4 inches of water per acre per application, for a total of 12–24 inches per growing season.
Can pivots irrigate sloped land?
Yes, but fields with a slope greater than 3-5% require careful alignment and pressure regulation to prevent water pooling or runoff. Compensating nozzles may be needed.
Is it difficult to operate a pivot system?
Modern computer controllers automate functions. Once programmed, pivots run with minimal oversight. Remote software also enables monitoring and adjusting operations remotely via computers or smartphones.
Conclusion
center pivot irrigation systems have revolutionized modern large-scale crop production. They do this by providing a labor-efficient way to evenly water big, circular fields.
Center pivots now dominate the world’s best farmland. They’ve done so for over 80 years since their invention.
Through continual innovation, pivots conserve water resources while helping farmers maximize yields.
Authorized dealers sustain them for decades. They do so by properly installing, maintaining, and upgrading components. These actions have kept these major investments and agricultural infrastructure profitable for decades.
