understanding agronomy. irrigation objectives describe the benefits of irrigation; describe the...
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Understanding Agronomy
Irrigation
Objectives Describe the benefits of irrigation; Identify ways to determine the need for i
rrigation; Explain methods of water application; Describe irrigation scheduling; and Describe efficient use of water.
Benefits of Irrigating What are some benefits of irrigating your
lawn? Green all summer Healthy Less weeds
What are the benefits of irrigating crops? Grow to maturity Healthy Produce highest yield possible
Benefits Irrigation also:
Provides water when it is not naturally available
Is a method to apply fertilizers Can protect crops from frost Reduces dust
Benefits What can happen if a plant is deficient
in water? Poor growth Stunted mature plants Lower crop yields (less $$) Death of plants Stress; more susceptible to disease Loss of aesthetics(looks)
Determining a need Knowing when to irrigate is important in
soil moisture balance Waiting for signs of stress is probably
too late Irrigate before the wilting point
Wilting Point: plant cannot take in water as quickly as it is lost
Determining a need Once a plant wilts damage has already
been done to production You should check soil moisture before
irrigating
Determining a need Lots of methods can be used to test soil moisture
without stressing the plant
Ribbon test We’ve done this
Ball test Roll a ball in your hand – if it crumbles you need water
Moisture sensor Single electronic probe that tests moisture content
Sap flow sensor Usually for trees or shrubs
Determining a need More methods
Tensiometer Determines pull of soil particles Permanently placed in soil Can be damaged by extreme weather
Moisture meter Uses two probes in the soil
Remote sensing Usually done with satellites
Ground truthing Verifies accuracy of remote sensing
Methods of Applying Water What made the “Fertile Crescent”
Fertile? Irrigation
How did they do it?
What are some methods we use today?
Methods of Applying Water Subsurface irrigation
Piping system that is underground Saturates the soil below plants and
through capillary action, water will rise to the root zone
Not common and can be expensive
Methods of Applying Water Trickle/Drip irrigation
Very controlled amounts of water Similar to subsurface but usually runs
above ground
Methods of Applying Water Surface irrigation Border Strip Irrigation
Both are very similar
Best on level to slightly sloped ground Canals and ditches are used to carry water to
the field Can be piped Evaporation can cause large amounts of
waste
Covers entire field
Covers sections of the field
Methods of Applying Water Furrow irrigation
Similar to the flooding
Water runs down furrows in between rows of crops
Usually same delivery system as flood Can be piped
Methods of Applying Water Sprinkler Irrigation
Several types
Usually pump water through a system of pipes
Good on ground that is not level
Methods of Applying Water Hand-Line sprinklers
Least expensive start-up Very labor intensive
Methods of Applying Water Solid Set
Same equipment as hand lines, but set in place and never moved
Much more equipment = higher cost
Methods of Applying Water Wheel lines
Pipe mounted on wheels The pipe plays the role of the axle Entire line moves all at once Less equipment than solid set, but less
labor than hand lines
Methods of Applying Water Traveling Gun
One large sprinkler head mounted on a cart that travels across the field
Can be affected greatly by wind
Methods of Applying Water Center Pivot
Central pivot point that an elevated pipe on wheels rotates around
Lowest labor requirement Sprinkler heads must be engineered to
release more water on the outside of the circle and less on the inside
Methods of Applying Water Linear systems
Same type of equipment as center pivot Entire line moves in a line
No pivot point The end tower carries a pump that draws
water from a ditch that runs the length of the field
Irrigation Scheduling Irrigation scheduling is providing the
right amount of water at the right time Scarce water supplies are used more
efficiently through scheduling
How is irrigation scheduled?
Irrigation Scheduling Water supplies are usually increased before
peak need Usually in the middle of the growing season
Most crops are not watered each day Needs are calculated and then water is applied at
a very specific period of time Some specialty crops are irrigated daily
The method of irrigation helps determine this Part of scheduling is acquiring an allocation and
time with the local water management district
Using Water Efficiently Why should we use water efficiently? How does it benefit us?
It is valuable; using more than you need will cost you lots of money
Your crops will be more productive if they are watered properly
Using Water Efficiently Some ideas to think about when
irrigating
Use during cool parts of the day or night time
Use when wind is not blowing Lots of water is lost through evaporation
when it is hot or windy
Using Water Efficiently Monitor moisture in the root zone
Saturating beyond the root zone can lead to leaching
Using Water Efficiently Avoid leaky irrigation systems
Apply water uniformly Do all areas of a field need the same
amount? Do all areas of your lawn need the same
amount?
No
Using Water Efficiently Use irrigation method best suited for
your land
Avoid runoff It can contain fertilizers, pesticides and
sediment that can pollute surface and ground water
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