Download Variable Rate Irrigation - Precision Agriculture, SOIL4213

Variable Rate
Irrigation
Cody Daft
April 13th, 2007
Precision Agriculture
• Where Have We Been
– Soil Sampling
– Yield Monitors
– GPS
• Where Are We At Today
– Greenseeker
– Variable Rate Technology
– Auto Steer
Why Use Precision
Agriculture?
• Why Adopt New Methods/Technology?
– 95% of all cropland in South America is no-till
• Bottom line= $$$$ Money
– Reduce Labor
– Intensive Management Strategies
• Environmental Control
Law of The Minimum
• Yields are directly
proportional to the
most limiting growth
factor
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Nutrients
Heat
Light
Water
Limiting Growth Factor
• Water is most limiting
growth factor in many
regions of the world
Limiting Growth Factor
• When a limiting growth factor, such as
water, is removed by installing an
irrigation system it will generally improve
plant response to fertilizer used to correct
nutrient deficiencies that are also limiting
growth
Irrigation
• For a large portion of the US, the single
most important production factor is
irrigation management
• Challenges
– Optimization of water use
– Environment
• CP systems are relatively efficient
– Uniformity
Uniform Application Over
A Non-Uniform Landscape
• Non-Uniformity may be a result of
– Irregularly shaped fields resulting in off-site
application of water
– Overlapping of CP systems
– Multiple crops under the same system
– Variability in soil type
– Variability in topography
Non-Uniformity
Variable Rate
Irrigation
• Site Specific Irrigation
• Delivery of irrigation water in optimum amounts
over an entire field
• Challenges
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Variability in soil texture
Variability in water holding capacity
Variability in water infiltration/drainage rates
Non-Uniform cropping patterns due to terraces
Variable Rate
Irrigation
• Match the non-uniformity of the field with
an appropriate non-uniform CP application
“CP systems are particularly well suited to
variable rate irrigation because of their
current level of automation and large
coverage with a single pipe.” (Evans et
al.,2000)
VRI: How Does It Work
• A GPS is mounted on
the end span of a
pivot.
VRI: How Does It Work
• A controller, much like
a spray controller, is
mounted near the
pivot point.
• It contains a "water
map" on a data card
programmed from a
desktop computer.
VRI: How Does It Work
• Uses information from GPS to control banks of
sprinklers which are then cycled on/off
according to a pre-determined prescription map
• Prescription maps are created using PC
desktop software
• The application map divides the circular area
covered by the pivot into 1-10° pie slices and
every slice is divided into segments
VRI: How Does It Work
• Application Maps
• The water map and
controller manage the
water rates.
VRI: How Does It Work
• Hydraulic valves are mounted at each
nozzle that is to be controlled, that is
turned off or left on when moving across
areas of the field to have a rate or
irrigation greater than or less than the
base rate.
• An air compressor provides the air to
close the hydraulic valves as directed by
the controller.
VRI: How Does It Work
• The controller communicates with electronic "node boxes"
mounted down the system. Each node box can control up
to EIGHT "banks" of nozzles.
• The controller tells which solenoids to open, allowing air
from the air compressor to pass through the solenoid,
closing the bank of nozzles associated with that solenoid
Variable Rate
Irrigation
http://www.nespal.org/irreff/howitworks.html
VRI Clip
Variable Rate
Irrigation
• Pivots can be programmed to
automatically shut off, to avoid overlap
and non-crop inclusions in the field
• Application rates can be pre-determined
for automatic rate control on different soil
types
• Accounts for spatial variability in the field
Variable Rate
Irrigation
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Improve uniformity
Save water
Optimize pumping costs
Help to keep water out of non-farmed areas
Prevent "double watering" where pivots
overlap.
• Improve irrigation management decisions
• Increase flexibility in fields with multiple
crops or planting dates
• Improve the benefits of other precision
agriculture practices
Variable Rate
Irrigation
• Base Cost of System: $7300.00
• Cost per Node:$1500.00
(1 to 4 nodes per system, depending on size)
• Cost per Variable Rate Valve:$32.00
(1 valve per sprinkler)
• Labor:$2200.00
(includes 1 year of technical support)
• Distance Surcharge:$2.00 per mile, miles greater than
100 from Ashburn, Georgia
(Example: location 500 miles away has a single charge
of $800, $2 X 400 miles)
• Hobbs & Holder, LLC / NESPAL / Farmscan
(Australia),