It is hard to mimic the rainfall in surface irrigation methods, even with the sprinkler system not perfectly replicating the rainfall, even though it can distribute water unevenly, which is problematic.
This is problematic to some growers like delicate plants, flowers, and greenhouses. To tackle the issue, overhead irrigation was introduced.
From small family farms to massive commercial operations, this irrigation technique has revolutionized how we deliver water to crops, landscapes, and agricultural spaces.
In this comprehensive guide, we’ll explore everything you need to know about overhead irrigation systems, their benefits, challenges, and the types.
What Is Overhead Irrigation?
As the name suggests, the system irrigating from above is called overhead irrigation.
The system mimics rainfall, distributing the water through the air above the crop or plants, allowing it to fall onto plants and soil below.
The fundamental working principle behind the system is simple yet effective. Water is pressurized and delivered through a network of pipes to sprinklers or nozzles positioned above the crop canopy.
These devices break the water stream into droplets, which then fall onto the target area in a controlled pattern. The size of water droplets, application rate, and distribution uniformity can all be adjusted to meet specific crop requirements and environmental conditions.
This method has become increasingly popular due to its adaptability to various terrain types, crop varieties, and field conditions.
Types of Overhead Irrigation
In the world of overhead irrigation, there are several types, each designed to meet specific needs and operational requirements.
Understanding these different systems is crucial for selecting the right solution for your agricultural needs.
Center Pivot System
I’ve dedicated a post about the Center Pivot System where you’ll get detailed information.
Briefly, the center pivot system is the system where irrigation pipes and sprinklers are mounted on a wheeled tower that rotates on a central pivot point, creating the distinctive circular field patterns visible from aerial views.
This massive structure effectively irrigates a land mass of 10 to even 500 acres. They offer exceptional uniformity in water application and can be automated for minimal labor requirements.
Advanced models feature variable rate irrigation technology, allowing growers to adjust water application rates based on soil conditions, crop needs, and topography as the system moves through different zones of the field.
Linear Move System
Linear or lateral move systems move in a straight line across the rectangular field rather than rotating in a circle.
These systems are ideal for fields with irregular shapes or those bordered by roads, buildings, or other obstacles that would prevent circular coverage.
Linear systems are generally more complex and expensive than center pivots and require a water source that moves with the machine or multiple connection points along the field, offering the advantage of irrigating the entire field area without leaving unirrigated corners.
Solid Set System
Like the above two types of systems, the Solid Set System does not move anywhere and consists of permanently installed pipes and sprinklers positioned throughout the field.
As a grower, you can customize the system, set up different zones, and set specific daytime schedules to irrigate.
Solid set systems are particularly popular in orchards, vineyards, and high-value crop operations where the initial investment can be justified by improved crop quality and management flexibility.
The downside is that it requires high initial cost and maintenance, considered for permanent crops or high-value applications.
Key Advantages of Overhead Irrigation
There are several advantages you’ll get from the overhead irrigation. Here are some important ones.
Uniform Water Distribution
Modern overhead irrigation delivers water uniformly across a large area.
This uniformity is important to grow crops healthier, achieve better yields, and avoid many diseases that come with under-watering.
When properly designed and maintained, overhead systems can achieve distribution uniformities exceeding 85 percent, meaning crops receive nearly equal amounts of water regardless of their location in the field.
This consistency is particularly valuable for crops destined for processing or markets with strict quality standards.
Labor Efficiency
With little to no labor intervention, overhead irrigation delivers water evenly.
Modern systems equipped with remote monitoring and control technology allow operators to manage irrigation from smartphones or computers, further reducing labor requirements.
These systems, which can operate reliably with minimal human intervention, provide significant competitive advantages and allow farms to scale operations without proportional increases in staffing.
Addressing the ongoing labor shortage and rising wage costs in the agriculture sector is important as an automated system.
Compatibility with Fertigation and Chemigation
Not only does it distribute water uniformly, but it can distribute fertilizers too.
Delivering fertilizers through irrigation is called fertigation. Overhead irrigation systems provide excellent platforms for fertigation and chemigation (pesticide or other chemical application).
The ability to deliver nutrients and chemicals through irrigation water improves application timing, reduces soil compaction from field traffic, and can improve product efficacy by ensuring thorough crop coverage.
This integration of irrigation and crop management practices represents a significant efficiency advantage for modern agricultural operations.
Flexibility in Application Rate
Overhead irrigation offers precise control over water flow, making it easy to match irrigation to crop water needs, soil infiltration rates, and weather conditions.
This flexibility helps optimize water use efficiency while preventing problems like runoff, deep percolation losses, or waterlogging.
Farmers can implement deficit irrigation strategies during specific growth stages, apply lighter, more frequent irrigations for shallow-rooted crops, or increase application rates for deep-rooted crops with high water demands.
Versatility Across Terrain Types
One of the big advantages of overhead irrigation is that no matter what the topography is, it functions effectively.
Unlike surface irrigation methods that require relatively flat, graded fields, overhead systems can operate on rolling terrain, hillsides, and fields with irregular contours.
Irrigation on uneven land means that, as a farmer, there is no need to have the expensive kit to level the land.
This not only reduces initial land preparation costs but also helps preserve natural soil structures and minimize erosion risks associated with large-scale grading operations.
Challenges and Consideration
Despite the advantages, overhead irrigation has its challenges. Recognizing these potential issues helps operators make informed decisions and implement appropriate management strategies.
Wind Drift and Evaporation Losses
Before reaching the plant, a strong wind can carry away the water droplets.
When water is sprayed into the air, especially in fine droplets, some percentage will evaporate before reaching the ground or be carried away by the wind. These losses can range from minimal in calm, humid conditions to 30 percent or more in hot, windy, arid environments.
Managing these losses requires careful attention to operating conditions and system design.
Using larger droplet sizes and lower trajectory sprinklers also helps minimize losses, though these modifications must be balanced against potential impacts on distribution uniformity and soil infiltration.
Energy Requirement
To operate, overhead irrigation needs a lot of energy to pressurize the distribution of water.
Center pivots, linear moves, and traveling guns all need pumps capable of maintaining adequate pressure throughout the system, leading to substantial electricity or fuel costs.
Optimizing energy efficiency involves selecting the right components for the appropriate system pressure, maintaining systems properly to minimize friction losses, and operating during off-peak electricity rate periods when possible.
Some are exploring renewable energy like solar as the energy source, though the high power requirements and timing of irrigation needs present challenges for solar applications.
Maintenance Requirements
All overhead irrigation systems require regular maintenance to maintain performance and reliability. Neglecting maintenance leads to decreased efficiency, poor uniformity, and potentially costly breakdowns during critical irrigation periods.
Maintenance like sprinklers needs cleaning and replacement, pipes may develop leaks, electrical systems require servicing, and mechanical components like wheel gearboxes need regular attention.
Establishing systematic maintenance schedules and keeping adequate spare parts inventories helps minimize downtime and maintain system performance.
Initial Investment Cost
Installing an overhead irrigation system even for an acre costs several hundred dollars, particularly center pivots and solid set installations.
While these initial costs are considerable, they must be evaluated against the long-term benefits of improved water management, labor savings, and potential yield increases.
Many operations find that modern irrigation systems pay for themselves within several years through improved efficiency and productivity, but the financing requirements can still present barriers for some farmers.
Crop Compatibility Issue
Not all crops are suitable for overhead irrigation. Some plants are susceptible to foliar diseases that can be exacerbated by wet leaves, while others may be physically damaged by large water droplets or high application rates.
Delicate crops approaching harvest may be damaged by overhead irrigation, and some flowering plants may experience reduced pollination when blossoms are constantly wet.
Understanding crop-specific requirements and limitations helps operators decide whether overhead irrigation is appropriate and, if so, how to manage systems to minimize potential problems.
In some cases, modifying irrigation timing, droplet size, or application rates can make overhead irrigation viable for crops that might otherwise be problematic.
Last Words…
Overhead irrigation is earning its place as the cornerstone of modern agriculture through its versatility, efficiency, and adaptability to diverse conditions.
Even though the initial investment cost and maintenance required are high, it provides unmatched capabilities for delivering water precisely when and where crops need it.
Success with overhead irrigation depends on careful planning and execution for different environments and crop types.
As technologies continue advancing and management approaches become more sophisticated, overhead irrigation will remain central to sustainable, productive agriculture worldwide.
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