Subsurface Drip Irrigation

Why are growers choosing Subsurface Drip Irrigation (SDI) ?

Subsurface drip irrigation (SDI) applies water beneath the soil surface, directly to the root zone of the crop. Here are just a few of the reasons growers are choosing SDI:

One of the most significant grower incentives to invest in SDI is related to increased crop yield and quality. SDI provides the most efficient way to deliver water and nutrients directly to the plant roots at the precise time and in the precise quantity the plant needs. Fertilizer can be directly applied uniformly to the root zone at any stage of growth on any day and with any dosage, without wetting plant foliage.

Potential savings and/or improved efficiency of water and fertilizers. Water and fertilizers are applied more uniformly and better crop response is possible with the same applied amounts. Irrigation efficiency is improved, improving energy efficiency.

SDI easily adapts to small and odd shaped parcels, allowing for complete irrigation coverage. Minimal land grading is required. It is the most effective form of irrigation, it delivers the water and nutrients into the root zone allowing for precision crop management.

SDI delivers water directly to the root zone, eliminates leaf wetness and reduces the relative humidity in the crop canopy which reduces disease pressures.

SDI provides a drier soil surface, minimizing weed growth and precision crop management. weed germination. Irrigating has less impact on field entrance of tractors and less soil compaction. Higher frequency irrigations are possible.

SDI decreases groundwater contamination and leaching of nutrients caused by over irrigation and poor irrigation uniformity.

SDI allows the use of recycled water while complying to environmental and public health regulations which prohibit overhead irrigation of certain crops with recycled water.

SDI can have a 90+% distribution uniformity (DU). Water and nutrients are not wasted due to wind, runoff, or evaporation.

Growers have also noted some additional observations after installing SDI including earlier harvests and a quicker turn-around time on planting the next crop.

Basic System Layout

SDI uses buried dripline with strategically spaced emitters and laterals as determined by soil type, crop variety, climate and growing practices a grower intends to use. The dripline is just one component of the SDI system, the other components have an integral part of the design. Above ground system components should be located in an easily accessible area and strategically located away from traffic. There are three distinct sections to a system: water source, control head and irrigation block.

Water Source

Drip irrigation water can be sourced from groundwater pumped from wells or surface water from reservoirs or canals.

Control Head

The pump moves water from the water source into the control head of the system.

Proper filtration is critical to the success of an SDI system. Use a pre-screen to protect filters from larger debris. Sand separators are a type of pre-filter used to spin sand out of the water before it goes into the primary filter. Sand separators are only needed when water has a large amount of sand. There are three types of primary filtration methods that can be used in an SDI system depending on water source and quality: sand media filters, screen filters and disc filters. Screen and disc filters work best with well water and good water quality sources. Sand media filters are the most versatile and can filter out both organic and inorganic materials. Sand media filters are tanks filled with crushed silica sand that acts as a filtration bed. These filters have the largest filtration area and will filter the worst water quality.

The flow meter serves as a visible indicator that the system is performing within design specifications.

Pressure gauges indicate the operating pressure of a system at any given moment.

The fertilizer injector is an efficient way to deliver nutrients in a liquid form to the field through the dripline.

Controllers are optional and can be used to automate the system.

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Eurodrip SA, is committed to providing only the highest quality and most reliable drip products that represent the industry's best value. Our commitment extends beyond great products to include industry-leading warranties knowledgeable, personal customer service.

Irrigation Block

Valves are used to manage pressure and flow in the field. Valves are available with a choice of control functions and connections to automate the system.

Air vents allow trapped air to escape the SDI system. All high points in the system should have air vents installed. When the system shuts down and begins to drain, a vacuum will occur if there isn’t a vacuum relief valve installed.

A back-up filter can be used at the irrigation block level to provide additional protection to the system.

Depending on the future plans for the field, a permanent PVC or a temporary layflat manifold can be installed to deliver the filtered water to the driplines in the field.

Dripline carries the filtered irrigation water and nutrition to the plants Eurodrip USA’s Classic Thinwall roots. Dripline thickness (measured in millimeters and referred to as Dripline and Classic dripper are ‘mil’), flow rate and spacing will be determined in the design process and is dependent on crop water requirements, soil type and length of each row. Eurodrip SA recommends 13 mil minimum for permanent burial in an SDI system.

When considering a switch to SDI, Eurodrip USA strongly recommends selecting a professional irrigation dealer, designer and installer. The true value of SDI is determined by a well planned and designed system.

Design Considerations

To ensure a good irrigation design, quality and correct field information must be gathered including the elevation/slope, water source information and plant water requirements. The information from the questions below will help the designer design an SDI system for efficiency and longevity.

What are the crops that will be grown? Will they be rotated?

What are the soil types found in the field?

What types of nutrients need to be applied through the dripline?

What is the water source? Is it sandy or have organics?

What flushing capabilities are needed for laterals and mains?

Does the system need to be automated?

Each of the above questions generates a different set of design parameters from water supply to pumping requirements, location of components, depth of installation, and spacing of drip lateral options that your irrigation designer can assist in selecting the appropriate system.

Hydraulic design should have a high distribution uniformity (DU), a high DU means that water is delivered evenly to the crops. The design will plan for appropriate mainline, submains, and thinwall dripline sizing, pressure control valves, determine the pump requirements and filter requirements, air vents and vacuum relief valves.

The design will also plan flushing zones for the system, a water velocity of 1.5 to 2.0 ft/second is required for adequate flushing. It is very important to design and size flushing manifolds properly, often the flushing manifold is as large or larger than the feeder manifold. The system might have fold-over dripline ends, valves or caps.

Installation Tips

Install driplines using GPS. Use the GPS lines later to manage tilling and cultural needs.

When installing thinwall dripline there are a few important things to watch:

• If the field is ripped, install dripline in the same direction.
• Avoid installing the dripline in very wet soil. Fine soil preparation before dripline installation greatly helps proper backfill and moisture movement in the soil.
• Check installation equipment for sharp edges and burrs that can damage the dripline during installation.
• Be careful cutting the wrapper off of the dripline spool.
• Install tape with emitters facing upwards to encourage water movement upwards and so any particles settle to the bottom of the dripline.
• Plan the path of the installation equipment so tight
turns are eliminated. Tractor installing subsurface drip
• Place the spool of tape directly above injection shank to irrigation for corn. minimize tape twisting and ensure that spools are tight against the dripline coil. Utilize a spool brake to prevent freewheeling. Check the depth of the dripline often.
• Change the dripline coils before they run out completely. It is easiest to splice the dripline during installation rather than coming back later.

Once the SDI system has been installed, run the irrigation system within 30 days to prevent compaction of dripline.

SDI Tractor installation

Maintenance Considerations

The system is designed to operate at specific pressures to ensure maximum efficiency. Most commonly seen problems related to maintenance revolve around plugging of emitters. Some commonly seen field scenarios include presence of organic and inorganic debris, root intrusion and chemical interactions. Here are some of the elements that need to be maintained on an SDI system to perform at peak efficiency and ensure a long life:

• Monitor system flows and pressures to keep the system running at top efficiency. Use a flow meter and pressure gauges to detect and troubleshoot potential problems.
• Perform periodic filter maintenance.
• An SDI system requires periodic flushing. Frequency of flushing is determined by water quality and the products that the grower puts through the system.
• Pest management is an essential maintenance function, rodents can be deterred by running the system since most rodents avoid a wet environment.
• Crop termination planning is also important. Root intrusion into the emitter flow path can occur if crops are allowed to continue to grow after system shut down, or if crops are intentionally stressed or dried down.
• Chemical injection is essential for sustaining drip irrigation systems. Consider these basic areas:
• Having a PH at 6.5 helps fertilizers and other dripline maintenance products perform better.
• A product that works to combat organics may be needed if surface water is used as a water source.
• Acid helps lower PH and break down inorganic buildup.
• Mix chemicals and water in a jar to determine any potential negative interactions prior to injection

Plugging Potential Hazard Levels

Maximize Yield through Efficient Delivery of Water and Nutrients

SDI increases the water use efficiency of applied water. It allows a grower to apply the needed water, optimizing crop performance at every physiological crop stage.

SDI also gives growers the flexibility to quickly and effectively apply nutrients to the root zone. Providing the right amount of nutrients at the right time promotes root development and improves crop development and yield.

If a grower’s goal is to reduce or contain water usage, SDI gives the ability to use available water in a highly efficient manner. If water savings is not a goal, water applied can be efficiently used to push the crop to its maximum potential.

Return on Investment (ROI)

Initial costs can be higher on subsurface drip irrigation systems compared to other types of irrigation systems. Growers can expect to see those investments returned to them within two to five years through higher yields and improved efficiency of inputs such as water, fertilizer, and energy.

To calculate ROI using specific input costs, use Eurodrip USA’s Drip Irrigation Payback Wizard at:

Subsurface Drip Irrigation (SDI) Installation

SDI Leaflet