got water? developed by: hud minshew oregon state university extension service susan donaldson...
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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?
www.farmphoto.com
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
OSU Extension Service
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
UNCE, Reno, NV
Irrigation systems:advantages and disadvantages
Drip
Flood
Sprinkle
NRCS Irrigation Page
Flood irrigation
UNCE, Reno, NV
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?
OSU Extension Service
Trickle or drip
USDA SCS
Drip irrigation
OSU Extension Service
Lateral wheel lines
USDA NRCS
Guns
USDA NRCS
Sprinklers
UNCE, Reno, NV
Portable handlines
www.fao.org
Applying water uniformlyApplying water uniformly
UNCE, Reno, NV
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