DIY: Irrigation The Basics for Small Home Gardens

Master Gardeners

February 19, 2013

Providing in the Garden • The main purpose for irrigating is to supply

needed water for crops

• Most vegetables need between 1/3”per day or 2 inches of water per week

• Can use a watering can, regular hose, sprinkler, irrigation system, drip hose

• Most people OVERWATER!!

• Account for natural precipitation

Where to place a rain gauge

Rain gauges should be placed in an open area away from trees, buildings, and other structures, as this may cause an inaccurate reading.

A general guideline to follow is placing the rain gauge twice as far away from the height of an object such as a tree.

Rainwater Capturing Systems According to EPA, 50-70% of total household water

is used for landscape irrigation and other outdoor activities.

The most practical way to use capture in gardens and landscapes is by drip irrigation using gravity.

# of gallons/1000 square foot area during rainfall events

Rainfall depth (in) Volume of water (gal)

0.5 310

1 620

2 1250

3 1870

PM 3017--Rainwater Catchment from a High Tunnel for Irrigation Use

• http://vimeo.com/38525142

Water spreads

differently in different soil

textures

2.5 – 5 feet spread

5 – 9 feet spread

9 – 14+ feet spread

CLAY

SILT

SAND

Soil Type and Irrigation

Jar Test

Where do plants get their water from in the root zone?

Adapted from PNW 475 by A. Miller

Garden Crop Rooting Depth

Plants will effectively take up water from all depths of their root zone (70% in the upper 50%)

– check soil moisture at 1/3 rooting depth

Root Zone Crop Depth (ft) Beans 2.0 Corn 2.5 Onions 1.5 Potatoes 2.0 Peas 2.0 Tomato 2.0

You know about how much, but when, or how often?

• Most plants become stressed when available soil moisture drops below 60%

• You can check soil moisture several ways:

– soil moisture sensors

– “feel” method

The Soil Moisture Feel Method

70-100% 50-75% 25-50%

While drought can impact plants, over-watering creates many concerns such as:

• Increases risk of pollution from yard and garden care products.

• Encourages shallow root zones and increases plant susceptibility to disease.

Water Conservation (or water management BMP’s)

Reduce need for watering by:

1) mulching

2) improving soil structure

3) irrigate only when the plants need water

4) drip-irrigation

Mulching • Protects the soil from erosion

• Reduces compaction from the impact of heavy rains

• Conserves moisture, reducing the need for frequent watering

• Maintains a more even soil temperature and moisture level

• Prevents weed growth

• Keeps fruits and vegetables clean

• Keeps feet clean, allowing access to garden even when damp

• Provides a "finished" look to the garden

Improving Soil Structure • Don’t Rototill…especially when soils are wet!!

• ADD Organic Matter!!!

Using sprinklers in the garden

• Convenient

• Increases chances of leaf burn

• Disease and pest issues increase

• Not efficient, 60-80%

Measuring sprinkler output

Step One – Checking Sprinkler Distribution

• Pick a calm day with little or no wind to check coverage. • Select five identical straight sided containers, (coffee cans, cat

food cans, etc.), then place them level on the lawn, 3 to 4 feet apart in a straight line.

• Turn the water on for 15 minutes. • After 15 minutes, turn off the water and measure the amount

of water in each can to the nearest 1/8 inch. Usually, each can will contain a different amount of water. If the water level between cans differs more than 1/4 inch, inspect the sprinkler nozzles for dirt or rocks that may be blocking the opening.

• With underground watering systems, it may be necessary to replace or add sprinkler heads, or divide an existing system into two or more lines. Some underground systems can be adjusted for more water coverage.

Measuring sprinkler output

Measuring sprinkler output

Step Two – Measuring Sprinkler Output • To measure the amount of water (in inches) that your

sprinkler puts out over a 15-minute period. • Use five identical straight sided containers placed level on

the lawn, space 3 to 4 feet apart in a straight line away from the sprinkler.

• Turn the water on and let it run for 15 minutes. • Using a ruler, measure and record the water accumulated

in each can to the nearest 1/8 inch. • Pour the four cans into the fifth, and measure the total

water content. Then divide that total by 5. You now have the average amount of water the sprinkler puts out in 15 minutes.

• Use this average to time your watering. Run the water only long enough to deliver water, two to three times a week.

Measuring sprinkler output

Can #1…3/8" (3/8")

Can #2…3/8" (3/8")

Can #3…1/4" (same as 2/8")

Can #4…1/2" (same as 4/8")

Can #5…3/8" (3/8")

Total 1 7/8" (same as 15/8")

Divide the total inches (15/8") by 5 = 3/8" to get the average inches of water per can.

Soaker Hoses

• Not as efficient as drip

• Needs filter and pressure regulator, hard water can clog

• Cannot bury or use on slope , can mulch over

• <50 ft best = uneven distribution

Drip Irrigation

Drip irrigation is an easy way to water your yard in the most efficient, least labor intensive manner. With a timer, it can be an automated system that will mostly take care of itself, requiring only a bit of maintenance to keep things running smoothly.

Application efficiency about 90-95%

Types of Drip Equipment

• Drip tubing with built-in emitters

• Drip tubing or poly pipe with punch-in emitters

• Drip tape with built-in emitters

In-line Emitters, AE=90-95%

Punch-in Emitters

• Allow watering only at each plant (eg. Best for plants spaced several feet apart

• Emitters should be punched in on the top or side of tubing to minimize plugging

• Usually 1-2 gal/hr emitters work well in silt or sandy soil

• For fruit trees, add multiple emitters to the tubing on each side of tree as it grows

Goof plugs (poly pipe)

Drip emitters and Spaghetti tubing

Drip Tape with Built-in Emitters

• Less expensive

• Can also be buried

• More subject to damage from hoes or rodents

• Provides a line source of water - good for irrigating rows in a garden

• 4 mil to 25 mil thickness

• Emitter spacing 2” up to 36”

• Flow rates: usually X gpm per 100 ft

– .25 up to 1.5 gpm/100 ft

• Filtration: 200 mesh for all tape

• Pressure: 10-15 psi

• ½”, 1”, and 2” tape width (for vol)

Drip Tape Specs

Soil Wetting Patterns

• Depend on emitter location

– max wetting at or near soil surface for surface location

– max wetting at depth of tape for subsurface location

– thickness of wet soil above emitter is about 1/4 wetted width for sandy soils and about 1/2 wetted width for silt or clay soils

Soil Wetting Patterns Depend on soil type

sandy soils: water moves deep with narrow wetted width. Max wetted width about 12-16”

silt or clay soils: water moves slightly deeper than wetted width. Max wetted width about 20-30 inches

Soil Type and Irrigation

Consideration is the type of soil that you have is important for determining drip irrigation details, spacing and flow of emitters • Clay Soil = water from emitters will tend to move farther away

from source, you might use a lower flow emitter (1/2 gph to 1 gph) • Sandy Soil = water moves further down but closer to source, you

might use a higher flow (1 to 4 gph) emitter while in a clay soil

Good for row crops

Great with plastic or row cover

Simple layout

Drip tape couplings

Tees & tubing

Elbows

Drip tape ends - plugs

Drip tape to hose connector

Shut-off valve

Flower pots

Zone sprinkler head adapter

Spray tubes & misc.

Foggers

Adjustable dripper

www.dripworks.com

Bucket kits

Infiltration and Flow-Through Planters h

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UAF CES Publications Catalog www.uaf.edu/ces/pubs/catalog/

Bottom line…..

• Be creative with the space, but make it functional.

• Irrigation timing and amount should depend on soil type and form of irrigation

• Stick your fingers in the soil as often as necessary.

• Don’t forget to MULCH!!!