Irrigation of Small Plots

L. Niel Allen USU Extension Irrigation Specialist

February 27, 2013

Photos taken April 5, 2006

Considerations for Irrigation

Land soils, topography, etc.

Plants and Crops Fruit, vegetables, ornamentals, pasture, grains, alfalfa

Water Supply City/municipal, private well, irrigation company

Water right

Flow rate, demand or rotation system

Irrigation Method Drip, sprinkler, surface

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Location Dimension and shape of the property

Exposure (sun, shade, etc.)

Topography (slope, north or south slope)

Soils (texture, chemical properties, limitations (gravels, water table, weeds, soil depth, etc.) Dig a few holes and look at the soil. We are irrigating

the soil.

Land Evaluation

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Plants and Crops

Annual Crops Vegetables

Ornamentals – flowers

Field Crops – small grains

Perennial Crops Field Crops - pastures, alfalfa,

Ornamentals – shrubs, flowers, trees,

Orchards

Berries, asparagus, herbs, grapes, etc.

Photo taken August 20, 2008

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Water Supply

Available Supply Municipal, private well, irrigation/canal company

Municipal water providers may have restrictions.

Irrigation company – open ditch, low pressure pipeline, or high pressure pipeline

Cost ($/1,000 gallon or $/acre-foot)

Quantity and pressure

Timing of availability Demand (24 hours/day, 7 days per week)

Rotation (For example, once each week for 4 hours)

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Water Costs Municipal Water Supplies Lowest would be about $1.00/1,000 gallon or $325/ac-ft

Typically about $1.50 to $2.50/1,000 gallons or $488 to $812/ac-ft.

Well Water Groundwater availability

Water right issue (may not be permitted or allowed)

Cost of well construction and pump (Could be $10,000 or more)

Energy costs (about $15-45/ac-ft per 100 feet of head)

Irrigation Company – Varies (<$10 to $100/ac-ft)

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Production per Unit of Water

Crop Production per Acre-Foot (approx.)

Alfalfa 2 tons

Onion 10,000 lbs

Sweet Corn 460 dozen ears

Wheat 50 bushel

Bell Peppers 7,500 lbs

Tomatoes 15,000 lbs or more

Green beans (hand pick) 4,000 lbs

Carrots 12,000 lbs

Cantaloupe 5,000 lbs

Apples 10,000 lbs

You wouldn’t grow alfalfa or wheat with $325/ac-ft water. You might consider other crops for home use fresh produce markets.

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Surface Irrigation System Considerations Topography (need proper field slopes and leveling)

Soil (more favorable to lower intake rates)

Water Supply (generally need higher flows)

Advantages Low energy requirement

Less water filtration

May work well for short duration high flow rates (irrigation turns)

Disadvantages Often less efficient that sprinkler or drip

Water supply may not work

Field layout may not work 8

Surface Irrigation

For small acreages use level fields with little or no slope. Irrigate each set in a few hours.

(Imperial Valley CA, by Chris Austin

Photo from Bob Hill

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Photos Taken April 13, 2012

Border Irrigation in Nevada

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Sprinkler Irrigation System Application Most small plots and crops

Same or similar crops and relatively large areas

Advantages Works with most topography and soils

Works best with nearly continuous water supply

Medium irrigation system costs

Requires screening water but not filtered like drip

Disadvantages Requires pressurized water

Some crops do better with dry foliage

Not capable of irrigating single rows or narrow strips

Can be impacted by wind 11

Sprinkler Irrigation

Photos by Bob Hill Super Stand Harward Irrigation 12

Solid set sprinkler used to germinate crops. Picture of carrot or lettuce bed after planting in Imperial Valley, CA

(Imperial Valley CA, by Chris Austin)

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Solid Set Sprinkler on Onion Field in Nevada. Notice something different about these sprinklers?

Photo taken April 13, 2012

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Drip Irrigation System Application Most small plots and crops Works best with nearly continuous water supply

Advantages Works with most topography and soils Good application uniformity and irrigation efficiencies Capable of irrigating single rows Fertigation with good uniform application

Disadvantages Requires pressurized water (less than sprinkler) Sometimes seed germination requires different system Requires filtered water to prevent plugging of emitters High costs of installation and maintenance Maintenance (rodents, plugging, leaks, etc.)

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Drip Irrigation

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Trampoline Hoop House Protect plants from hail Provide a better environment for plants

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Irrigation System Costs

Cost vary based on water supply, area being irrigated, and degree of automation.

Irrigation Method Estimated cost per Acre

Surface $100 to $1000

Sprinkler – Solid Set $1,700 to $2,000

Sprinkler – Hand Line $500 - $750

Sprinkler – Permanent (buried) $2,000 to $2,500

Drip (tube v. tape & spacing vary cost)

$2,500 to $4,500

Micro-Sprinkler $2,500 to $3,000

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Drip is feasible on Row and Permanent Crop

Drip Irrigated Acreage in California

Toro Drip Manuel

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Drip Cost Factors Drip line spacing (18” up to 72”).

Tape (8 mil to 12 mil wall thickness) v. Tubing/Drip line (45 mil).

Diameter of tape and drip line (5/8” (16mm) to 1 3/8” (35mm)).

Degree of automation (Manual v. Smart Irrigation Controllers)

Pressure compensating v. non-pressure compensating emitters.

Filtration needs (screen or disk filters v. sand media filters.

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Help is Available Manufactures have all sorts of charts and graphs to

help you select the right drip tape or drip line.

Irrigation equipment suppliers can generally help with design and selection of hardware.

There is a lot of flexibility in design options.

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Installation Connection to Water Source (pump or pipeline)

Backflow prevention and vacuum breaker.

Filtration (media filter, screen filter (200 mesh), disc filter.

Pressure regulation.

Mainlines and manifolds.

Valves (Manual or Automatic). I use automatic valves for main blocks or zones and then manual valves for individual manifolds and rows.

Drip lines or tap (buried or surface lines).

Spacing, flow, and number of emitters.

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Large Field Drip Irrigation System Components Toro Drip Manual

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Small Plot Simple Drip System

http://www.irrigationtutorials.com/drip-parts.htm

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Low-tech, gravity-fed drip irrigation system. (New Mexico State University, Dan Smeal, 2007

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Used in Personal Gardens and Yard Plant Drip Practice

Raspberry About 30” drip line spacing (Contained patch 14’ x 10’)

Strawberry About 30” drip line spacing

Grapes Drip line along ground

Fruit Trees Loop around larger trees

Gladiolus and Dahlias About 3 feet drip line spacing with row (about 12 inches between rows) on each side of tape

Annual Flowers (Zinnia and many others)

About 24” rows

Perennial flowers and shrubs 12 – 18” rows (however plants are not always planted in rows)

Onions Two drip lines on onion bed with either 4 or 6 rows of onions 26

Used in Personal Gardens and Yard Plant Drip Practice

Carrots Two drip lines on carrot bed with either 4 or 6 rows of carrots

Green Beans One drip line between two rows of beans spaced about 9 inches apart

Peppers One line per row of peppers spaced about 18” along row.

Tomatoes One line per row of tomatoes spaced about 24” apart.

Squash and Cucumbers One line per row, one plant every 12 to 24” along row depending plant type.

Cabbage, Cauliflower, Broccoli, Brussels Sprouts

One line per row with plants spaced at 18 inches.

Chard, spinach, lettuce, etc. One drip line for two rows with row spacing about 9 inches apart.

Dill, Cilantro, Basil, etc. One drip line for two rows with row spacing about 9 inches apart. 27

Example of on drip tape for two rows of vegetables

Toro Micro-Irrigation 28

Additional Examples of

Drip Irrigation

NRCS, USDA Photos Luis Garcia/Mauro Herrera

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Drip Tubing/Line Emitters Spacing Consider the soil and crop.

Germination of shallow seeds like carrots and lettuce can be an issue.

Closer spacing helps wet the surface for a more uniform germination.

0.22 gpm/100 ft for 30 hrs. is 2.5 inches for 30 inch spacing

Some growers use sprinklers to establish the crop.

Toro Micro-Irrigation 30

Drip Irrigation in Vineyard (San Joaquin Valley CA, by Maven (aka Chris Austin)

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How many feet of tubing can I operate with my water supply? Can be designed to accommodate water supply. Pressure compensating emitters best for long lines. A typical outdoor faucet can provide about 5 gallons per minute.

Drip Tubing/Tape for various water

supplies (feet)

Drip Tubing/Line/Tape (gallon per minute per 100 feet)

0.17 0.33 0.50 0.67 0.83 1.00 1.17 1.33

Drip Tubing/Line/Tape (gallon per hour per 100 feet)

10 20 30 40 50 60 70 80

Water Supply Flow

(gallons per minute)

5 3000 1500 1000 750 600 500 429 375

10 6000 3000 2000 1500 1200 1000 857 750

15 9000 4500 3000 2250 1800 1500 1286 1125

20 12000 6000 4000 3000 2400 2000 1714 1500

25 15000 7500 5000 3750 3000 2500 2143 1875

30 18000 9000 6000 4500 3600 3000 2571 2250

35 21000 10500 7000 5250 4200 3500 3000 2625

40 24000 12000 8000 6000 4800 4000 3429 3000

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How long can a single row be with drip tape/tube? Can be designed for 5 feet to more than 1,000 feet. Pressure compensating emitters best for long lines. The Chart is for pressure compensating emitters.

Toro Micro-Irrigation 33

How much time should I run an irrigation set? Two step process: first determine the application rate based on the irrigation tubing and spacing.

Application Rate (inches/hour)

Drip Tubing/Line/Tape (gallon per minute per 100 feet)

0.17 0.33 0.50 0.67 0.83 1.00 1.17 1.33

Drip Tubing/Line/Tape (gallon per hour per 100 feet)

10 20 30 40 50 60 70 80

Line Spacing (inches)

6 0.32 0.64 0.96 1.28 1.60 1.92 2.25 2.57

12 0.16 0.32 0.48 0.64 0.80 0.96 1.12 1.28

18 0.11 0.21 0.32 0.43 0.53 0.64 0.75 0.86

24 0.08 0.16 0.24 0.32 0.40 0.48 0.56 0.64

30 0.06 0.13 0.19 0.26 0.32 0.38 0.45 0.51

36 0.05 0.11 0.16 0.21 0.27 0.32 0.37 0.43

42 0.05 0.09 0.14 0.18 0.23 0.27 0.32 0.37

48 0.04 0.08 0.12 0.16 0.20 0.24 0.28 0.32

60 0.03 0.06 0.10 0.13 0.16 0.19 0.22 0.26

66 0.03 0.06 0.09 0.12 0.15 0.17 0.20 0.23 34

How much time should I run an irrigation set? Two step process: Step two is to determine the time based on application rate.

Time (minutes)

Irrigation Depth (inches)

0.5 0.6 0.7 0.8 0.9 1 1.1 1.2

Application Rate (inches/hour)

0.05 600 720 840 960 1080 1200 1320 1440

0.1 300 360 420 480 540 600 660 720

0.2 150 180 210 240 270 300 330 360

0.3 100 120 140 160 180 200 220 240

0.4 75 90 105 120 135 150 165 180

0.5 60 72 84 96 108 120 132 144

0.6 50 60 70 80 90 100 110 120

0.7 43 51 60 69 77 86 94 103

0.8 38 45 53 60 68 75 83 90

0.9 33 40 47 53 60 67 73 80

1 30 36 42 48 54 60 66 72 35

How many acres can I irrigation with my water supply? Generally more than with surface irrigation or sprinkler. Gross

Application Rate

(inches/day)

Flow Rate (gpm/acre)

0.25 4.7

0.27 5.1

0.29 5.5

0.31 5.8

0.33 6.2

0.35 6.6

0.37 7.0

0.39 7.4

0.41 7.7

0.43 8.1

The peak ET in northern Utah is about 0.3 inches per day. With the high efficiencies of drip irrigation a flow rate of about 7 gpm per acre is adequate. The system would only need to operate continuously only during dry periods when crops are maturing. The peak ET in southern Utah is about 0.34 inches per day. With the high efficiencies of drip irrigation a flow rate of about 8 gpm per acre is adequate. Crop and Wetland Consumptive Use and Open Water Surface Evaporation for Utah Prepared by Robert W. Hill, J. Burdette Barker and Clayton S. Lewis, UAES Research Report 213 – August 2011

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Irrigation Scheduling for Drip

Drip irrigation provides a lot of flexibility. Adjust based on plant maturity and ground cover

Adjust irrigation depth based on changes in weather, temperature, sunshine, humidity, and wind. Utah State University Agricultural Weather Network information.

Frequency of Irrigation Can irrigate every day to maintain optimal soil moisture

I found it convenient to irrigate once every three days and adjust percentage timer based on plant maturity and climate.

http://climate.usurf.usu.edu/agweather.php

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Irrigation Scheduling Example

Toro Micro-Irrigation 38

Management of Drip System

Maintain filtration system to prevent plugging. It doesn’t hurt to have backup filtration; one at water source and one near tubing manifolds. Align tubing so emitters are on top to keep sand and grit from emitters.

Periodic flushing of lines, may only be annually depending on water.

Monitor connections and tubing for leaks.

Monitor for bacterial and fungus slimes (my 20 years of experience is that it is not a problem with municipal water supplies).

Drain or blowout system in fall.

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Micro-Sprinklers

Well suited for established trees and orchards.

Small spray or mini-sprinkler that spreads water above ground. Water is emitted through an orifice.

Could be a spinner or a spray plate that directs water.

Wetted diameter from a few feet up to 20 or 30 feet.

Flow rates from 3 gallon per hour (0.05 gpm) to about 30 gallons per hour (0.5 gpm)

Less prone to clogging than drip.

Can easily see if there is a problem with sprinkler.

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NRCS USDA Photos 41

Questions

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