Got Water? Got Water? Developed by: Developed by: Hud Minshew, Oregon State University Extension Hud Minshew, Oregon State University Extension Service Service Susan Donaldson, University of Nevada Susan Donaldson, University of Nevada Cooperative Extension Cooperative Extension UNCE, Reno, Nev.
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Got Water? Developed by: Hud Minshew, Oregon State University Extension Service Susan Donaldson, University of Nevada Cooperative Extension UNCE, Reno,
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Got Water?Got Water?
Developed by: Developed by: Hud Minshew, Oregon State University Extension ServiceHud Minshew, Oregon State University Extension Service
Susan Donaldson, University of Nevada Cooperative Susan Donaldson, University of Nevada Cooperative ExtensionExtension
UNCE, Reno, Nev.
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Today we’ll learn aboutToday 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
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Where will you get your Where will you get your water?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
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So you think you’ll use your So you think you’ll use your domestic well to irrigate a pasture?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.
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Things to know before Things to know before you start to irrigateyou 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.
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More things to know before More things to know before you start to irrigateyou start to irrigate
Do you want to improve existing pasture, or start over?
How much time and money do you have?USDA Online Photos
Where do plants get their water Where do plants get their water from in the root zone?from in the root zone?
Adapted from PNW 475 by A. Miller
Plant Plant rooting rooting depths depths
varyvary
A. Miller
Alfalfa4’ – 6+’
R
oo
tin
g D
ep
th in
Fe
et
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Before you pick a crop, Before you pick a crop, consider the soilconsider 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
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Water = 20 to 30%
Air = 20 to 30%
Mineral Fraction
(sand, silt,clay) = 45 to 50%
Organic Matter = 0 to 5%
Composition of a loam soilComposition of a loam soil
Soil Soil texturetexture
How does it feel in your hand?
NRCS, Bozeman, Mont..
Water Water spreads spreads differently differently in in different different soil soil texturestextures
Deepest penetration
Moderate spread and infiltration
Wide, but more shallow, infiltration
CLAY
SILT
SAND
Soil texture and drainageSoil texture and drainage
Soil textureInfiltration rate, inches per hour
Sand 2 - 4
Sandy loam 1 - 3
Silt loam, loams 0.25 – 1.5
Silty clay loams, clay 0.1 – 0.3
A. Miller
Available waterAvailable 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
OSU Extension Service
Available waterAvailable water
A. Miller
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The water available to youThe water available to youDoes 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.
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When is it time to irrigate?When is it time to irrigate?
Rule of thumb: when the amount of water-holding capacity is at 50% – but that’s hard to tell!
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 MethodThe Look-and-feel Method
USDA NRCS
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Look-and-feel methodLook-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
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Look-and-feel methodLook-and-feel methodSandy 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.
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Screwdriver methodScrewdriver method
UNCE, Reno, Nev.
Using evapotranspiration data Using evapotranspiration data to schedule irrigationto schedule irrigation
Bureau of Reclamation
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Irrigation water qualityIrrigation 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-Salt-affected affected
soilssoils
USDA-NRCS
Irrigation methods: selecting the Irrigation methods: selecting the system that’s right for yousystem that’s right for you
Micro-irrigationMicro-irrigation
SurfaceSurface
SprinkleSprinkleUSDA NRCS
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Are you using an existing Are you using an existing system, or starting over?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
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What source of power What source of power will you use?will you use?
None – select an irrigation system that does not require power