Irrigation Systems

What is Irrigation?

Irrigation is the process of providing water to a field or garden through a man made system. This may include simple ditches from a water source, a series of troughs or pipes to channel water, an overhead or a drip system.

What is Overhead Irrigation?

Overhead irrigation is used to provide water to large fields by spraying water at high volumes into the air to reach the plantings over a given time. These systems are highly mechanized, may be computer controlled and may move through the field under their own power.

This system is designed for large farms where it would be impossible to water manually. Overhead irrigation is expensive, complex, requires a large water source and looses much of the moisture to evaporation.

What is Drip Irrigation?

Drip Irrigation is the controlled release of water to specific locations in a garden at a given rate over a given time. This type of system is designed for small farms and home gardeners.

Drip irrigation conserves water by only emitting a small amount of water right to a plant’s roots at or near the ground level. The water source may be a well or city water. The installation is efficient because the water is delivered at a controlled rate so the water soaks in causing little run off or evaporation to the air.

A drip irrigation is an affordable way to provide water to a garden. The parts of a drip irrigation system are simple and inexpensive. Many of the parts will last several years. Those that require replacing, like the drip tape or black plastic, are inexpensive alternatives to hand watering. Drip irrigation uses less water than a sprinkler or garden hose, so the cost of water is reduced.

A drip irrigation system saves time and is more efficient than watering with a hose or sprinkler. A drip irrigation system, once in place, saves time because many areas of the garden can be watered at the same time even though they may have different plantings in them. In addition, the drip system is far more efficient as water only goes where it is needed and is not lost to evaporation or dispersed where there are no plant roots.

What are the parts of a drip irrigation system?

There are three distinct parts of a drip irrigation system. They are: the water source, the infrastructure of main and sub-main pipes and connectors and the components making up the emitter devices.

What types of water sources will work for drip irrigation?

A small farm may need a different water source from a home garden. A small farm may have rows upon rows of a vegetable or fruit where the home gardener may have one plot and flower beds to irrigate.

The most common type of water sources are a well or spring, a public water source or a farm pond. The water is pumped from the source to the irrigation system using either a well pump or water tank. Before the water enters the system, it passes through a filter that reduces sediment which would block the tiny emitters. A back flow stop is needed to prevent water from the system from returning to the source if fertilizers are dispensed through the irrigation system.

Some unconventional ways to provide water for irrigation include a gutter system or pumping water to a tank in the second story of a barn, for example.

An irrigation system may use valves to separate fields from each other or one garden plot from another. This provides the ability to irrigate one zone at a time. This method of establishing watering zones allows for watering only those areas that need water. It also allows a limited water source to provide water to a large area by watering a zone or one part of a zone at a time.

How do you design a drip irrigation system?

Step 1: Draw an ACCURATE map of your gardens or fields on graph paper or with a computer design program. Distances are important considerations in your design due to the resistance limits within the piping. Additionally, this map will help you determine what types of irrigation to use and what components you will need to connect the system.

The next step in designing an irrigation system is to determine what it is that you need to irrigate. Specify on your map drip vs. other types of irrigation methods.

Then, determine how much water your source can provide and at what pressure. By comparing the volume the source can provide against what is needed, zones may be created to then section off areas to comply with the need.

It is not possible to water an area larger than your water source can provide. Similarly, you can not exceed the pressure limit the piping sets up. Because of resistance, there is a limit for how far water will travel through a pipe before the pressure is reduced to an unusable amount.

How do you determine how much water your source provides?

The best method is by filling a 5 gallon bucket from your source over a given time increment, like a minute for example. Most drip irrigation systems are connected to a source through either a garden hose or a PVC piping system.

First turn on the water and let it run so your pump is actually pumping and not just drawing water from a full tank. There is a pressure difference between water from a full tank and the pressure when your tank is drawing water from a well for example.

In either case, time for 1 minute while filling the bucket. At the end of 1 minute, turn off the water. If the bucket fills faster than a minute, try timing for 30 seconds.

Then, estimate how much water is in the bucket. If you fill the bucket, that means your source provides 5 gallons per minute. If it is half full, that means your source provides 2.5 gallons per minute.

If you are using 30 seconds, multiply the amount by 2 to get the amount of water per minute.

Then multiply by the amount by 60 minutes to find out how much water your source provides in an hour. In the case of 5 gallons per minute, that results in 300 gallons per hour.

How do you design the system now that you know how much water you can work with?

Once you know how much water the source provides and what your irrigation needs are, section off the target areas into zones. The major pipe from the source is called the main and each zone will use a pipe called a sub-main. The sub-main may be the same size or smaller than the main. This system of main pipes, sub-mains and valves will create the infrastructure that supports the drip system.

Because of resistance there is a limit to how far water can travel through pipes and retain its water pressure. Wider diameter pipes have less friction loss per gallon of water. Also, changes in grade will affect water pressure.

What are the parts of the infrastructure in a drip irrigation system?

The infrastructure is that part of a drip irrigation system that moves water from the source through the main pipes to each sub-main in the zones in the design.

Valves and “T”s connected to the main pipe channel water from the source to each zone. From the main, use “T”s ,“L”s and valves to section off each sub-main in a zone. Clamps go on either end of a “T”, “L” or valve to prevent leaking. Use plumber’s tape on the threads of connectors that connect the main or sub-main to the valve.

Finally, within each zone, use inline valves to section off each area from the sub-main as needed to match the volume of water your source provides and your irrigation needs within a zone. Use ends to terminate each pipe.

Filters, Valves & Ends
Source hose connected to the filter then to the Main pipe.	In-line Valve on ½” pipe	End on ½” pipe

Infrastructure
	Infrastructure Components 1. ½” PVC pipe 2. Valve for ½” pipe 3. End for ½” PVC Pipe 4. “T” for ½” pipe 5. “L” for ½” pipe 6. Connector for ½” pipe 7. Clamp 8. ½” Goof plugs 9. Punch

How is the infrastructure installed?

Start by having careful measurements of all lengths of piping. Measure twice, cut once.

Bring the source water out to where the irrigation system begins. Then connect the filter and back flow inhibitor making sure the filter is pointed in the right direction for water flow. Connect the backflow inhibitor after the filter. This will stop fertilizer from going from the irrigation system back into the water source if you fertilize your plantings through the irrigation system.

Put plumber’s tape over threads of connections that hook up to a hose.

Test the system for water flow.

Then, connect the main pipes to the filter or backflow inhibitor. Use “T”s, “L”s, valves and appropriate clamps to hold the pipe securely to the connectors. Test for water flow before closing off the system at an end.

Then, connect the sub-main pipes to the main pipes and test the water flow before closing off the end.

Use holding stakes to keep the main and sub-main pipes in place through out.

Then, install the drip system and test. Seal any leaks with silicone.

Main Pipe connecting to a sub-main
	The main pipe comes in at the bottom and turns left using an “L”. A “T” starts the sub-main. A short pipe connects to an “L” to make the right turn. A valve opens and closes the whole sub-main. Valves connect each run of drip tape to the sub-main allowing individual control.

What types of emitters are available?

Emitters are available in two formats. The first type drips water from an emitter right to a plants root system at the soil surface. The second type of emitter, a micro-sprinkler, sprays water into the air at a controlled rate over a selected pattern.

While spraying is not dripping, it is almost as efficient because the variety of spray nozzles aim water selectively and the flow rate is controlled like drip emitters.

How do drip emitters work?

Drip emitters use a regulator at each emitter to control the flow of water through the emitter. The regulators change the pressure in the sub-main pipe down to the specified amount for the emitter. For example, a regulator may change the 5 gallons per minute down to ½ a gallon an hour. The emitter may be connected to the sub-main or it may be a part of the emitter itself as in the case of drip tape. Electronic timing devices can schedule watering cycles automatically also.

What type of drip emitters are there?

Drip emitters are available to meet a variety of needs. For example, a row of tomatoes is best irrigated using drip tape. Drip tape is thin plastic pipe with emitters built into it at regular intervals. The tape is sold in different lengths for each interval. Some common intervals are 8”,12”, 18” 24” and 36”. The rolls may be 100’, 200’, 400’, 1000’ or more.

The other type of drip emitters include devices that connect directly to the sub-main. Some drip right at the sub-main and are inserted where needed while others connect to the sub-main with a ¼” tube and connectors. The regulator built into these drip devices controls the amount of water that is dispensed over a given time. Some of these devices are useful for potted plants in a greenhouse. Some are on short ¼” tubes for moving it about manually on a regular basis.

There is also a variety of connection devices including “T”s, “L”s & bends to get the ¼” tube to where it is needed.

Emitter Components
	Emitters, Connectors & Parts 1. ½” PVC Pipe 2. Drip Tape Connector w/ valve 3. Drip Tape 4. ¼” Tube Connectors 5. Emitters 6. ¼” Tube 7. 360 Emitter 8. Stake to hold ¼” tube in the air 9. Punch 10. ¼” Goof Plug

What type of spray emitters are available?

Spray emitters are most effective on flower plantings since flowers in gardens are not usually planted at regular spacing. However, some of the spray emitters are also useful with vegetables. Spray emitters spray in 360, 180 or 90 degrees. Each nozzle can be swapped out to meet the changing needs of a garden. Additionally, different spray nozzles spray different distances.

The regulator is built into the emitter in spray emitters. This controls the amount of water that is dispensed. The type of emitter controls the angle.

How are spray emitters installed?

Spray emitters, sometimes called micro-sprinklers, are connected to the sub-main through a ¼” tubing.

Start by using the ¼” punch to create a hole in the sub-main near where the emitter will be placed. Then, insert the ¼” connector into the sub-main.

Cut the appropriate length of ¼” tubing to go from the sub-main to where the emitter will be located. Insert stakes stake to hold the tubing. At the end, insert the upright stake to hold the emitter in the air.

Insert the spray emitter into the end of the ¼” tubing as far as it will go. Snap the tubing onto the upright stake so the emitter is at the right height to reach the target plants without obstruction.

An installed spray emitter
	The ½” sub-main uses a connector to the ¼” tubing. The stake holds the tubing at the appropriate height. The emitter is inserted into the end of the tubing.

How can moisture be conserved in the soil?

1 mm thick black plastic can be fitted onto a planting row to conserve moisture. The plastic goes over the drip irrigation system and helps to mulch the soil and prevent evaporation.

This plastic mulch will also help suppress weeds. The plastic must be tight to the ground to be effective. The plastic is available in different widths to meet different situations.

How is the black plastic mulch installed?

Install black plastic mulch manually or with an attachment connected to a tractor. Many attachments will also install the drip tape under the black plastic at the same time. Black plastic mulch is not difficult to install just time consuming. It is more time consuming on a windy day.

To manually install:

First, rake the planting row smooth and even with a metal rake. Install the drip tape or sub-main.

Then, hoe a 4” deep x 3” wide furrow down the length of each side of the planting row.

To install, anchor the plastic to one end of the garden row. Then, pull the plastic roll down the row about 6’ and pull the whole roll taught while centering it on the row.

Next, shovel the soil from the furrow onto the black plastic to hold it in place over the whole distance down the row on each side.

Pull the plastic down another 6’ and repeat.

Be sure to leave at least one emitter from the drip tape exposed to measure where the other emitters in the row are so you can plant at the appropriate spots.

Plant through the plastic by cutting a slit or making an X at the planting site. The plastic is good for one season.

Black Plastic Mulch over Drip Irrigation
	Black plastic mulch helps conserve water by preventing evaporation. It also helps to suppress weeds. Plant through the plastic by cutting a slit or making an X at the planting site. The plastic is good for one season. Install black plastic either manually or with an attachment on a tractor.

Can a drip system be hidden?

You can mulch over a drip system from the main down to the ¼” tubing. Be sure not to use a heavy mulch like 1” stones on the fine tubing. Bark mulch, straw or other common mulches hide the system without interfering with its efficiency.

How do you winterize and maintain a drip system?

System maintenance is fairly easy.

The whole system should be checked regularly for leaks. Patch any leaks around valves or connectors with Silicone.

Next, the filter should be flushed out to keep the water flow efficient and to know how much sediment is getting into your system. This will help determine if your using the right filter. Clean the filter each month during the season.

Winterize your system by emptying out all the water in the system. A low pressure air hose may be used to remove any remaining water. Be sure it is low pressure! The point is that some water left in the system will not cause a problem but a full pipe or tube will break in the winter cold.

Most other parts like emitters and valves need no regular maintenance. Clogged emitters can be cleaned with a fine wire or by removing and cleaning with an air hose.

It is a good idea to install extra valves in the system at low points to aid in emptying the system in the fall. Use a “T” and a short length of pipe to connect the valve.

What other types of irrigation are available?

Soaker hoses

Soaker hoses are a common “drip” type of irrigation. They are usually made from recycled tires. They are light and easily bend around any angle needed. However, soaker hoses emit water along their entire length, sometimes wasting water by dropping it between plants where it is not needed.

Homemade Drip Bottles:

Recycle small plastic soda bottles, milk jugs or juice containers by drilling holes in them along the bottom and sides from ½ way down. Then, bury the bottle standing up in the garden near a plant’s root system. Leave the neck above ground with the cap on. To use, remove the cap and fill with water from a hose. The water will penetrate to the depth of the bottle and spread out in all directions at root level.

Who sells drip irrigation systems?

Some drip components, like soaker hose is available at garden stores locally.

Many of the components in a drip system, like the main and sub-main PVC pipes, clamps, “T”s and “L”s are also available at a hardware store or plumbing supply store.

Companies that specialize in irrigation are spread around the country. Attached are a few companies from the Knox Extension Service. Of note, The Drip Store has an excellent help section on their web page that applies to a variety of systems.

Dellamano Farm Supply

8145 State Rt. 104

Oswego, NY 13126

Contact: Francis Dellamano

315-343-1323

Fax 315-343-7387

The Drip Store

395 North Hale Ave.

Escondido, CA 92902

www.dripirrigation.com

Griffen Greenhouse Supply

50 West Gray Rd.

Gray, ME 04039