Got Water?

Developed by: Hud Minshew, Oregon State University Extension Service

Susan Donaldson, University of Nevada Cooperative ExtensionUNCE, Reno, Nev.

Today we’ll learn about Sources of irrigation water:

◦ surface versus well water

Matching available water to:◦ soils and plants

Determining when it’s time to irrigate

Irrigation systems

Where will you get your water?

Do you have a water right?

Where will your water come from?

When or how often will you get your water?

www.farmphoto.com

So you think you’ll use your domestic 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, Nev.

Things 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 you selected? UNCE, Reno, Nev.

More things to know before

you start to irrigate Do you want to

improve existing pasture, or start over?

How much time and money do you have?

USDA

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

Adapted from PNW 475 by A. Miller

Plant rooting depths vary

A. Miller

Alfalfa4’ – 6+’

R

ootin

g D

epth

in F

eet

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 spreads differently in different soil textures

Deepest penetration

Moderate spread and infiltration

Wide, but more shallow, infiltration

CLAY

SILT

SAND

Soil texture and drainage

Soil texture Infiltration rate, inches per hour

Sand 2 - 4Sandy loam 1 - 3Silt loam, loams 0.25 – 1.5Silty clay loams, clay 0.1 – 0.3

A. Miller

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

Wat

er C

onte

nt (%

vol

ume)

Available Water

Field Capacity

Wilting Point

Unavailable Water

OSU Extension Service

Available water

A. Miller

The water available to you Does your 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?

UNCE, Reno, Nev.

When is it time to irrigate? Rule of thumb:

◦ When the amount of water-holding capacity is at 50%

If your plants are showing signs of stress, irrigation is overdue ◦ Look for wilting or grasses that don’t spring

back up when stepped on

The Look-and-feel Method

USDA NRCS

Look-and-feel method

Clay, clay loam or silty clay loam at

25 to 50% moisture

Clay, clay loam or silty clay loam at

50 to 75% moisture

Irrigation is overdue. Will need to irrigate soon.

USDA NRCS

Look-and-feel method

Sandy loam or fine sandy loam at 50 to 75%

moisture

Sandy loam or fine sandy loam at

25 to 50% moisture

Irrigation is overdue. Will need to irrigate soon.

Screwdriver method

UNCE, Reno, Nev.

Using evapotranspiration data to schedule irrigation

Bureau of Reclamation

COAgMet - local weather station info and daily ET rates. A great resource to know when to

irrigate based on weather and EChttp://www.coagmet.colostate.edu/

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

USDA-NRCS

Irrigation methods: selecting the system that’s right for you

Micro-irrigation

Surface

SprinkleUSDA NRCS

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

What source of power will you use?

None – select an irrigation system that does not require power

Electricity from an existing power line An internal combustion engine Solar power◦This one pictured is not able to support a pressurized irrigation system. Can handle a stock tank though!

USDA NRCS

Surface irrigation (gravity-flow)

NRCS Irrigation Page

UNCE, Reno, Nev.

UNCE, Reno, Nev.

Wild-flood irrigation

UNCE, Reno, Nev.

Field leveling

USDA NRCS

Level- basin irrigation

USDA NRCS

Corrugation

UNCE, Reno, Nev.

CSU Cooperative Extension

Furrow irrigation (level and graded)

USDA NRCS

Furrow irrigation with siphon tubes

USDA NRCS

Components of a border irrigation system

USDA NRCSA. Miller

Gated pipe

USDA NRCS

UNCE, Reno, Nev.

USDA ERS

Surge irrigation

ERS USDA

Water delivery is controlled by a valve.

Alfalfa valves

Univ. of Idaho Extension

Bubbler screen

B. Hamblen, CSU Extension

Reducing return flows

Reusing tailwater Do you have a legal right to reuse tailwater?

How will you capture and store the water for subsequent use?

Maximizes the use of surface irrigation water.

Ditch maintenance

Who will do it, and what will it cost?

Dredging and re-digging Weed and vegetation

control Open/close gates Adjusting siphon tubes Permission and access

issuesOSU Extension Service

Powered systems: sprinklers

UNCE, Reno, Nev.

Center-pivot

USDA NRCS

Mini-pivot sprinklers

USDA NRCS Mont.

Low-energy precision-applicationsprinklers

USDA NRCS

USGS

Traveling guns (big gun)

USDA NRCS

www.clemson.edu

Traveling mini-guns

USDA NRCS

K-line® and Irripod® sprinklers

www.k-linena.com kygraziers.com

Hand lines

ERS USDA

USDA NRCS

Side roll/wheel lines

USDA NRCS

USDA NRCS

Solid-set sprinkler

UNCE, Reno, Nev.

Univ. of Idaho Extension

Below-ground popups

USDA SCS

Drip irrigation

Drip irrigation

USDA ARS

USDA NRCS

Subsurface drip irrigationUNCE, Reno, Nev.

Checking your system:Does it apply water uniformly?

UNCE, Reno, Nev.

Improving uniformity Monitor your system during irrigation

and 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 availabilityMatch 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 Checklist for Landowners Activity Sheet.

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