Water use in food production is a growing problem in the face of climate change and a rising global population. Water is an increasingly scarce global resource, and agriculture is the biggest consumer of our planet’s finite water resources. Globally, agriculture uses 70% of the world’s fresh water supply and 95% of all water withdrawals in some developing countries.
Drip irrigation is the most water-efficient irrigation system, capable of dramatically reducing a farm’s water use while increasing crop yields and quality. But, like every irrigation system, drip irrigation isn’t a magic bullet. Drip irrigation is expensive to install and labor-intensive and may not pencil out in lower-value crops.
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What is Drip Irrigation?
Drip irrigation is a low-pressure system for precision water delivery. It uses a system of pipes, tubing and emitters or sprinklers. Drip irrigation is also sometimes known as trickle irrigation or micro-irrigation and water is delivered in low amounts but over long periods of time.
Compared to traditional irrigation methods such as center pivot irrigation or flood irrigation, a drip or micro-irrigation system can increase a farmer’s water efficiency by up to 70% and reduce energy costs by 50%.
Drip irrigation occurs at the ground level, significantly reducing evaporation loss and eliminating water runoff, two significant inefficiencies in other irrigation systems. Drip irrigation pipes or tubing are closed off with an end cap, allowing the water flow to pressurize through the length of the pipe. This creates the pressure that forces the water to drip (or spray) out from the emitter points.
Although different types of pipes can be used for drip irrigation, including PVC and galvanized iron, the most common way to deliver water in a drip irrigation system is via flexible polyethylene or ‘black roll pipe.’ Depending on the crop, soil type, and production practices, drip irrigation lines may be laid to soil or buried.
Is Drip Irrigation the Same as Micro Irrigation?
Drip irrigation and micro-irrigation are slightly different low-pressure, precision-delivery irrigation systems. Micro-irrigation systems are also sometimes called micro-spray.
In a true drip irrigation system, water does indeed ‘drip.’ Either from the slits in the tubing itself or drip irrigation emitters mounted at the base of a plant. Micro-sprinkler irrigation uses the same piping and low-pressure delivery to bring water to the field as drip irrigation. But, in a micro-irrigation system, water is delivered through small, low-pressure sprinkler devices mounted on short risers staked into the drip tubing.
Micro-irrigation sprinkler heads are adjustable for how wide of an area they spray although a 3 to 10 feet diameter is most common. The spray pattern can be adjusted to accommodate for different pattern diameters, like part of a circle or a full circle. Operators can also change the spray method by switching out the sprinkler heads. Bubblers, misters, streams and spray pattern sprinkler nozzle heads are all options.
A micro-irrigation system is helpful for crops that have a widespread, like strawberries, or if farmers need to utilize their irrigation system to help cool off their crops during hot weather. A micro-irrigation system is also preferred in sandy soils because they disperse water over a larger area. Versus when water is delivered from a true drip system on sandy soils the water tends to move directly down rather than in a horizontal pattern and may not provide adequate soil moisture to support crop growth.
Drip Tape – How Does It Relate to Drip Irrigation?
Drip tape is a specific method of delivering water in a drip irrigation system. Drip tape has slits of cuts purposefully manufactured inside a thin-walled drip tube pipe, eliminating the need for individual emitters.
Drip tape varies in thickness and the spacing between slits. In sandier soil or with crops planted close together, the spacing of emitters should be a minimum of 12″ apart. Farmers mostly use drip tape in annual vegetable or cut flower production. It is generally considered a single-use product, installed, removed and disposed of in a single season.
Crops Most Commonly Irrigated with Drip Irrigation
Any crop can be irrigated with drip irrigation. However, drip irrigation is most commonly used in high-value specialty crop production such as vegetables or perennial crops such as berries and fruit trees.
Home gardeners often use drip irrigation kits or micro irrigation systems in landscape plantings or vegetable gardens.
Commercial vegetable row crop producers benefit from drip irrigation in multiple ways-low water and energy use, reduced weed pressure, and higher quality produce less subjected to disease and pest pressure. This helps to reduce food waste at harvest time and can help offset the higher expense of a drip irrigation system.
Components of a Drip Irrigation System
Whether using a drip irrigation system with emitters, micro-sprinklers, or drip tape, all drip irrigation systems are set up using the same basic components and design factors.
Drip irrigation may use water from a pond, irrigation ditch, groundwater or municipal water source (such as county or city water) simply by connecting to a standard faucet from a garden hose. However, high iron content, which may exist in well systems, is unacceptable for drip irrigation systems as it clogs emitters.
A pumping system moves the water to the field from the source. Pumping systems may be electrical, diesel, gas or even solar-powered. Because drip irrigation systems are low-pressure systems, even gravity can be used to pressurize drip lines, unlike center pivot irrigation or sprinkler irrigation systems. In a gravity-fed system, farmers have access to water from a mounted water tank or barrels.
The distribution system carries the water from the source to the field head and is connected to a mainline. A distribution system may be a PVC pipe or any tube large enough in diameter to deliver the needed quantity of water to the field. Depending on the crops in production, the distribution system may be permanent versus moveable (such as a flat tube).
Flexible tubing typically ½ inch in diameter. In the case of a drip irrigation system, mainline tubing typically runs at the head of the irrigated field and drip tape is connected to it, running at a 90-degree angle into the field. In the case of micro-sprinkler irrigation, smaller diameter mainline tubing typically is fed into a larger diameter header and sprayers are punched into the tubing where needed.
Drip Tape or Drip Tube
The drip tape or drip tube runs off the mainline tubing. Drip tape has slits designed into the tube so that water drips out. A drip tube requires emitters inserted wherever a drip point is desired.
Drip irrigation is a low-pressure system, running around 25 pounds per square inch (PSI) pressure but most pumps or water systems deliver well above that much water pressure. Pressure regulators monitor the pressure rate so the drip lines aren’t blown out while in operation and start leaking.
Screened filters are used to remove dirt, sediment and debris that would clog up emitters, micro-sprinklers and drip tape lines. Filters are essential if water is sourced from a pond, irrigation ditch or stream. In that case, a farmer may install a larger, more robust filter at the pump site.
Emitter tubing is small, flexible tubing inserted into drip tubing or mainline tubing and anchored to a point where the water drips out.
Sprayers and Emitters
Micro-irrigation sprinkler nozzles or sprayers installed on short risers inserted into drip tube. Emitters are inserted into the drip tube.
A device that mixes and fertilizer or chemicals with water and sends it through the drip line. This allows farmers to use their drip irrigation system for fertilizing and crop protection needs.
A gauge that prevents water from being siphoned back into the water source. This is particularly important if farmers source water from a potable source (such as a home well or municipal water system).
A programmable controller that monitors the amount of water sent through the system and turns the system on and off. System controllers are often part of the drip irrigation manifold controlling the entire system. A controller may include next-gen technology, such as variable-rate irrigation systems allowing farmers to respond to current field moisture conditions.
Goof Plugs, Valves, Flush Valves and More
There are many parts to a drip system, depending on the complexity. Goof plugs plug holes in mainline tubing that are no longer needed. Valves are used to turn different sections on and off. Flush valves at the end of mainlines and even drip lines flush out debris or sediment in case of clogging. Connectors connect two lengths of mainline pipe or drip tape together. Adapters connect a larger diameter tube to a smaller one.
The Pros of a Drip Irrigation System
Drip Irrigation is Water, Energy and Fertilizer Efficient
Drip irrigation is the most water-efficient irrigation system, with up to 90% water use efficiency especially compared to sprinkler systems, flood irrigation or center pivot irrigation. Because drip irrigation is a low-pressure method for delivering crop watering needs, it can also have low energy requirements. When combined with injector systems, farmers can also save on their fertilizer and pesticide use by capitalizing on the precision level of a drip irrigation system.
Drip Irrigation Increases Crop Yields and Quality
Because drip irrigation systems deliver water at the root zone level, it avoids promoting leaf scalding or humid conditions that can lead to pests, crop disease and reductions in crop quality that reduce harvest yields.
Drip Irrigation is Adaptable
Drip irrigation systems are highly flexible. They can be designed for any size and shape of the field. Drip irrigation systems are also easily expandable and can be used even with low water pressure.
The Cons of a Drip Irrigation System
Drip Irrigation is Expensive
Drip irrigation is the most expensive irrigation system to set up and manage, requiring significant amounts of labor for installation, removal, and seasonal maintenance. For this reason, drip irrigation is typically not seen in large acreage commodity crops and is more often used in high-value specialty crop production.
Drip Irrigation is Prone to Maintenance Intensive
Drip irrigation cannot be used in areas with high iron content in the water (typical of some groundwater systems) as it clogs up drip irrigation emitters and sprinklers. It is also prone to damage from rodents or field cultivation.
Drip Tape Irrigation Systems Create Plastic Waste
Drip tape systems, especially, are a source of single-use plastic because the drip tape is typically only used for one season before removal and disposal.
New Technology and Drip Irrigation Systems
New technology helps farmers get the most out of their drip irrigation systems, essential to offset the costs of installing and maintaining a highly efficient, but expensive drip irrigation system.
Variable Rate Drip Irrigation
Variable-rate irrigation is the concept of varying when, where and how much water is irrigated onto precise locations on a field depending on moisture conditions.
Variable-rate irrigation systems typically work in conjunction with advanced field monitoring solutions such as satellite and drone imagery, soil moisture sensors, weather stations, and even sensors monitoring crop evapotranspiration. A variable rate drip irrigation monitor turns a drip irrigation system on and off in response to real-time field conditions data.
Farm Software Management Systems for Drip Irrigation Systems
AGRIVI is an all-in-one solution for irrigation system management that works for drip irrigation as well as any other style of irrigation.
Our team of in-house agronomy experts can help you with expert advice on the best irrigation system for your farm. In addition, AGRIVI’s software platform automates your irrigation needs through our IoT hardware. As a result, AGRIVI gives farmers the tools they need to make data-driven decisions to optimize the efficiency and costs of their drip irrigation system.
Farmers can easily record and track irrigation activities such as frequency, water source, and fertigation events and compare that data against crop yield and quality. AGRIVI can also help manage the maintenance and labor of a drip irrigation system.
Drip Irrigation FAQs
Drip or Trickle? What Should I Use?
Drip irrigation and trickle irrigation systems are the same thing. Some people call drip irrigation trickle irrigation.
Drip or Sprinkle – What’s Better and Why?
A farmer’s needs determine what type of irrigation system is best suited for them. A drip irrigation system is an excellent choice when water is in scarce supply and the farmer is growing a high-value crop that will substantially benefit from practices that increase crop quality. A sprinkler irrigation system is a cheaper system to install and operate and is better suited to deliver large volumes of water quickly when water is more available.
How Long and How Often to Water with Drip Irrigation?
How long and how often to water with drip irrigation varies greatly depending upon the soil type, crop and weather conditions, flow rate, and emitter spacing. The design of the site will calculate water flow, pressure and how long drip lines. However, generally speaking, a drip irrigation system will need to run for three to five hours to deliver 1″ of water, and most crops will need to be watered at least once, if not multiple times a week.
How Deep Should Drip Irrigation Lines Be Buried?
The polyethylene plastic tubing used for drip tape or drip tubes only needs to be buried about 6″ inches underground in a drip irrigation system. However, drip tape and even mainline tubes are often laid on the ground and not buried. One advantage to burying drip irrigation is preventing damage from crop cultivation however, lines buried under soil or mulch are more susceptible to rodent damage.