got water? developed by: hud minshew oregon state university extension service susan donaldson...

Got Water?Got Water?Developed by: Developed by:

Hud MinshewHud MinshewOregon State Oregon State University University Extension ServiceExtension Service

Susan DonaldsonSusan DonaldsonUniversity of University of Nevada Nevada Cooperative Cooperative ExtensionExtension

UNCE, Reno, NV

Today we’ll learn about: Sources of irrigation water: surface

vs. well water Matching available water to soils

and plants Determining when it’s time to

irrigate Methods of irrigation

Where will you get your water?

Do you have a water right?

Where will your water come from?

When or how often will your get your water?

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So you think you’ll use your well to irrigate a pasture?

Does local law allow use of domestic well water for pasture irrigation?

Does your well produce enough water?

UNCE, Reno, NV

What do you need to know before you start to irrigate?

What plants do you want to grow?

Do you have enough available water to support the plants?

Are your soils appropriate for growing the plants?

UNCE, Reno, NV

What do you need to know before you start to irrigate?

Do you want to improve existing pasture or to start over?

How much time and money do you have?

USDA Online Photos

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

Adapted from PNW 475 by A. Miller

Plant rooting depths vary

A. Miller

Before you pick a crop, consider the soil:

What is the capability class of the soil?

What are the slopes and aspects?

How deep is the soil? Does it have adequate

drainage and rooting depths?

Is compaction an issue?

USDA NRCS

Water = 20-30%

Air = 20-30%

Mineral Fraction

(sand, silt,clay) = 45-50%

Organics = 0-5%

Composition of a loam soil

Soil texture

How does it feel in your hand?

Water spreads differently in different soil textures

2.5 – 5 feet

spread

5 – 9 feet spread

9 – 14+ feet spread

CLAY

SILT

SAND

Soil texture and drainage

SandSilt Loam Clay Loam

Coarse Texture

Medium Texture

Fine Texture

Available water

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

Sand SandyLoam

Loam SiltLoam

ClayLoam

SiltyClay

Clay

Finer Texture

Wa

ter

Co

nte

nt

(% v

olu

me

)

Available Water

Field Capacity

Wilting Point

Unavailable Water

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Available water

A. Miller

The water available to you

Does your surface water right supply enough water?

Will you have water during dry years?

Do you need to reduce your irrigated acreage to match your water supply?

Can you use your water more efficiently?

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Are you using an existing system, or starting over?

Your flexibility may be limited with an existing system, but costs will be lower

Starting over allows you to carefully match soils, plants, and water availability with irrigation systems, but can be costly

New irrigation systems may save time, money, or water

When is it time to irrigate?

Rule of thumb: when the amount of water holding capacity is at 50 percent -- but that’s hard to tell!

If your plants are showing stress, then irrigation is overdue Look for wilting or grasses that don’t

spring back up when stepped on

The Look and Feel MethodThe Look and Feel Method

USDA NRCS

Look and feel methodClay, clay loam, or silty clay loam at 25-50% moisture.

Clay, clay loam, or silty clay loam at 50-75% moisture.

Irrigation is overdue Will need to irrigate soon

USDA NRCS

Look and feel method

Sandy loam or fine sandy loam at 50-75% moisture.

Sandy loam or fine sandy loam at

25-50% moisture.

Irrigation is overdue Will need to irrigate soon

Screwdriver methodScrewdriver method

UNCE, Reno, NV

Using evapotranspiration data to schedule irrigation

UNCE, Reno, NV

Irrigation water quality

Does your irrigation water contain trace elements that may affect plant growth?

Is the water salty? What are upstream users doing that

might affect your water quality?

Salt-affected soils

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Irrigation systems:advantages and disadvantages

Drip

Flood

Sprinkle

NRCS Irrigation Page

Flood irrigation

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NRCS Irrigation Page

Components of a flood irrigation system

Wild flood irrigation

UNCE, Reno, NV

Gated pipe

NRCS Irrigation Page

Reducing return flows

OSU Extension Service

Ditch maintenance

Dredging and re-digging

Weed and vegetation control

Opening and closing of gates

Who will do it, and what will it cost?

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Trickle or drip

USDA SCS

Drip irrigation

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Lateral wheel lines

USDA NRCS

Guns

USDA NRCS

Sprinklers

UNCE, Reno, NV

Portable handlines

www.fao.org

Applying water uniformlyApplying water uniformly

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Improving uniformity Monitor your system during irrigation

– check for leaks or clogging of screens

Look for areas that remain too wet or too dry and adjust your irrigation system

Check sprinkler system pressures and nozzles to make sure they are adequate

Consider system upgrades

The can method for measuring uniformity – a low cost approach

OSU Extension Service

Irrigation systems summary

Know your sources of irrigation water

Know your soil type Monitor soil moisture Improve efficiency of your

delivery system when possible

Irrigation systems summary

Adjust rate of water application to avoid runoff

Know your labor availability Match your goals for your land

to the irrigation system you select

Homework

Practice the Look and Feel Method for determining irrigation

Inventory your irrigation system, both existing and proposed, using the Irrigation Check List for Landowners Activity Sheet

Check the uniformity of your sprinkler system, using any of the methods discussed in this lesson