Download Module 2, Lesson 3 - University of Nevada Cooperative Extension

Got Water?
Developed by:
Hud Minshew, Oregon State University Extension Service
Susan Donaldson, University of Nevada Cooperative
Extension
UNCE, Reno, Nev.
Today we’ll learn about
Sources of irrigation water: surface
versus well water
Living n
Matching available water to soils and
plants
Determining when it’s time to irrigate
Irrigation systems
the Land
Where will you get your
water?
Do you have a water
right?
Living n
Where will your
water come from?
When or how often
will you get your
water?
the Land
www.farmphoto.com
So you think you’ll use your
domestic well to irrigate a pasture?
Living n
Does local law allow
use of domestic well
water for pasture
irrigation?
Does your well
produce enough
water?
UNCE, Reno, Nev.
the Land
Things to know before
you start to irrigate
What plants do you
want to grow?
Living n
Do you have enough
available water to
support the plants?
Are your soils
appropriate for
growing the plants
you selected?
the Land
UNCE, Reno, Nev.
More things to know before
you start to irrigate
Living n
the Land
Do you want to
improve existing
pasture, or start
over?
USDA Online Photos
How much time
and money do
you have?
Where do plants get their water
from in the root zone?
Adapted from PNW 475 by A. Miller
Rooting Depth in Feet
Alfalfa
4’ – 6+’
Plant
rooting
depths
vary
A. Miller
Before you pick a crop,
consider the soil
 What is the capability
class of the soil?
Living n
 What are the slopes and
aspects?
 How deep is the soil?
 Does it have adequate
drainage and rooting
depths?
 Is compaction an issue?
the Land
USDA NRCS
Composition of a loam soil
Living n
Mineral
Fraction
(sand, silt,
clay) = 45 to 50%
the Land
Water = 20 to 30%
Air = 20 to 30%
Organic Matter = 0 to 5%
Soil
texture
How
does it
feel in
your
hand?
.
NRCS, Bozeman, Mont.



CLAY
SILT
Moderate
spread and
infiltration
SAND
Deepest
penetration
Wide, but more
shallow, infiltration
Water
spreads
differently
in
different
soil
textures
Soil texture and drainage
A. Miller
Soil texture
Sand
Sandy loam
Infiltration rate,
inches per hour
2-4
1-3
Silt loam, loams
0.25 – 1.5
Silty clay loams, clay
0.1 – 0.3
0.4
Water Content (% volume)
0.35
Field Capacity
0.3
0.25
Available Water
0.2
0.15
Wilting Point
0.1
Unavailable Water
0.05
0
Sand
Sandy
Loam
Loam
Silt
Loam
Clay
Loam
Silty
Clay
Clay
Finer Texture
Available water
OSU Extension Service
Available water
A. Miller
The water available to you
Does your water right
supply enough water?
Living n
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?
the Land
UNCE, Reno, Nev.
When is it time to irrigate?
Living n
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 Land
The Look-and-feel Method
USDA NRCS
Look-and-feel method
Living n
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.
the Land
USDA NRCS
Look-and-feel method
Sandy loam or fine
sandy loam at
25 to 50% moisture
Living n
Irrigation is overdue.
the Land
Sandy loam or fine sandy
loam at 50 to 75%
moisture
Will need to irrigate
soon.
Screwdriver method
Living n
the Land
UNCE, Reno, Nev.
Using evapotranspiration data
to schedule irrigation
Bureau of Reclamation
Irrigation water quality
Living n
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?
the Land
Saltaffected
soils
USDA-NRCS
Irrigation methods: selecting the
system that’s right for you
Surface
Sprinkle
USDA NRCS
Micro-irrigation
Are you using an existing
system, or starting over?
Your flexibility may be limited with an
existing system, but costs will be lower
Living n
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
the Land
What source of power
will you use?
None – select an irrigation system that
does not require power
Living n
Electricity from an existing power line
An internal combustion engine
Solar power
the Land
Surface irrigation (gravity-flow)
UNCE, Reno, Nev.
NRCS Irrigation Page
UNCE, Reno, Nev.
Wild-flood irrigation
Living n
the Land
UNCE, Reno, Nev.
Contour-ditch irrigation
Living n
the Land
Univ. of Virgin Islands
Field leveling
USDA NRCS
Levelbasin
irrigation
USDA NRCS
Corrugation
UNCE, Reno, Nev.
CSU Cooperative Extension
Furrow irrigation
(level and graded)
Living n
USDA NRCS
the Land
USDA NRCS
Contour-furrow irrigation
Living n
the Land
Icrisat.org
Furrow irrigation with
siphon tubes
USDA NRCS
USDA NRCS
Components
of a border
irrigation
system
A. Miller
USDA NRCS
Gated pipe
Living n
UNCE, Reno, Nev.
USDA ERS
USDA NRCS
the Land
NRCS Irrigation Page
Surge irrigation
Living n
Water
delivery is
controlled
by a valve.
the Land
ERS USDA
Alfalfa valves
Living n
the Land
Univ. of Idaho Extension
Bubbler screen
Living n
the Land
B. Hamblen, CSU Extension
Reducing return flows
Living n
the Land
USDA NRCS
OSU Extension Service
Reusing tailwater
Do you have a legal right to reuse
tailwater?
Living n
How will you capture and store the
water for subsequent use?
Maximizes the use of surface irrigation
water.
the Land
Ditch maintenance
 Dredging and redigging
 Weed and vegetation
control
Living n
 Opening and closing of
gates
 Adjusting of siphon tubes
 Who will do it, and what
will it cost?
 Permission and access
issues
the Land
OSU Extension Service
Powered systems:
sprinklers
UNCE, Reno, Nev.
Center-pivot
Living n
the Land
USDA NRCS
Mini-pivot sprinklers
Living n
the Land
USDA NRCS Mont.
Low-energy precision-application
sprinklers
USDA NRCS
USGS
Traveling guns
(big gun)
www.clemson.edu
Living n
the Land
USDA NRCS
Traveling mini-guns
USDA NRCS
K-line® and Irripod® sprinklers
Photo source?
kygraziers.com
www.k-linena.com
Hand lines
Living n
ERS USDA
the Land
USDA NRCS
Side roll
wheel lines
Living n
the Land
USDA NRCS
USDA NRCS
Solid-set sprinkler
UNCE, Reno, Nev.
Below-ground popups
Living n
the Land
Univ. of Idaho Extension
Drip irrigation
Living n
the Land
Graphic by A Miller, adapted from USDA-SCS 1984
USDA SCS
Drip irrigation
USDA NRCS
USDA ARS
Subsurface drip irrigation
Living n
the Land
UNCE, Reno, Nev.
Activity
Living n
Create a table showing the pros
and cons of each of the
irrigation systems discussed.
the Land
Living n
Checking your system:
Does it apply water uniformly?
the Land
UNCE, Reno, Nev.
Improving uniformity
Monitor your system during irrigation
and check for leaks or clogging of
screens
Living n
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 Land
The can method for measuring
uniformity – a low-cost approach
OSU Extension Service
Irrigation systems summary
 Know your sources of irrigation
water
Living n
 Know your soil type
 Monitor soil moisture
 Improve efficiency of your
delivery system when possible
the Land
Irrigation systems summary
Adjust rate of water application to
avoid runoff
Living n
Know your labor availability
Match your goals for your land to
the irrigation system you select
the Land
Homework
Practice the Look-and-feel Method for
determining irrigation.
Living n
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.
the Land