Transcript Irrigating Orchards Efficiently for Water and Energy Savings Allan Fulton UC Farm Advisor Tehama County.

Irrigating Orchards Efficiently for Water
and Energy Savings
Allan Fulton
UC Farm Advisor
Tehama County
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Reducing Water and Energy Costs
• Hours of irrigation and/or pumping
• Unit energy cost
• Horsepower or kilowatt demand
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Steps to Reduce Hours of Irrigation or
Pumping
• Manage orchard floor vegetation
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Orchard Floor Vegetation Management
• Normal and wet years generally encourage orchard
floor vegetation
o
o
Helps soil tilth and infiltration rates
Important BMP to control runoff
• Dry years are the exception
o
o
Consumes winter rainfall, reduces reserve
May increase in-season water use up to 25%
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Steps to Reduce Hours of Irrigation or Pumping
• Manage orchard floor vegetation
• Operate and maintain irrigation systems that apply
water uniformly
5
Evaluations Completed 2002 - 2007
DU Average, Maximum, Minimum
Source: Tehama County RCD Mobile Irrigation Lab
DU
2002
2003
2004
2005
2006
Completed
Max
Min
Average
Completed
Max
Min
Average
Completed
Max
Min
Average
Completed
Max
Min
Average
Completed
Max
Min
Average
Completed
Max
Min
Average
Total
Max
Min
250
191
200
150
98
97
98
97 87
95
96
96 86
82
79
77
67
100
59
53
47
45
42
42
41
33
26
18
50
13 17
13
0
2007
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Applied water (inches)
Distribution Uniformity vs Irrigation Requirement
5
4.5
4
3.5
3
2.5
2
1.5
1
0.5
0
Crop needs 2” of water
0.85
0.7
0.6
Distribution Uniformity
0.5
Sources of Non-uniform Irrigation with Drip
and Microsprinkler
•
•
•
•
•
•
Particulate plugging
Chemical plugging
Biological plugging
Pressure and flow variability
System changes
Under-designed systems
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Causes of Non-uniform Flood Irrigation
• Soils with high water intake properties
• Slow water advance across checks
–
–
–
–
Field lengths too long or checks too wide
In-flow too low
Field slope irregular and/or too flat
Rough soil surface conditions
• Not set up to capture and reuse tailwater runoff
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Steps to Reduce Hours of Irrigation or Pumping
• Manage orchard floor vegetation
• Operate and maintain irrigation systems that apply
water uniformly
• Modify irrigation systems for young trees
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Steps to Reduce Hours of Irrigation or Pumping
• Manage orchard floor vegetation
• Operate and maintain irrigation systems that apply
water uniformly
• Modify irrigation system for young trees
• Irrigation scheduling and regulated deficit
irrigation
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Irrigation Scheduling
•When to irrigate
•How much water to apply
•Prevent soil moisture from limiting crop
• Avoid excess deep percolation and irrigation
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Irrigation Scheduling Tools
• Weather and ETc monitoring
• Soil moisture monitoring
• Crop stress monitoring
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Use evapotranspiration
(ET) data from weather
stations to estimate
crop water needs:
•Solar Radiation
•Wind Speed
•Relative Humidity
•Air Temperature
wwwcimis.water.ca.gov
Spatial CIMIS ETo Reporting
Many types of Dielectric sensors
Regulated Deficit Irrigation – Going a
Step Further with Irrigation Scheduling
• Purposely allowing crop water stress
• Control timing and extent of crop stress
• Reducing crop ET
• Not affecting yield or minimizing effect
• Optimizing profits per unit of water or energy
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How Does Crop Stress Reduce Crop ET?
Microscopic view of leaf surface
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Tools to Manage Crop Stress
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Example of Water Savings from Using Crop Stress in
Almonds (Glenn County, 2005-2008)
Irrigation
Treatment
4 –year Avg
Yield (pounds
nutmeats/acre)
4-year Avg
Nut Size
(grams per
kernel)
Water Use
Efficiency (gallons
water/pound
nutmeats)
Control1
2,640
1.21
458
Regulated
Deficit
Irrigation2
2,640
1.18
428
Significance
NS
0.02 *
NS
1 Consumptive
use for control 3.8 acre-feet per acre
Consumptive use for Regulated Deficit Irrigation 3.3 acre-feet per acre
3 Water savings of 0.5 acre-feet per acre (13 % reduction in hours of pumping)
2
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Steps to Reduce Irrigation and Pumping Hours
• Manage orchard floor vegetation
• Irrigation system maintenance and improvements
• Irrigation scheduling and regulated deficit
irrigation
• Use practices that favor water infiltration not
evaporation
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Practices that Favor Water Infiltration
• Longer intervals between irrigations
– Alternate check irrigation with flood irrigation
systems
• Longer set times (within limits)
• Minimize irrigation in mid afternoon
• Soil and water amendments
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Ways to Reduce Energy Unit Cost
• Compare energy sources and costs
– Various rate structures for electricity
– Fossil fuels
– “Green” energy sources
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Ways to Reduce Energy Unit Cost
• Compare energy sources and costs
• When rainfall is low, winter irrigate?
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Benefits of Winter Irrigation
• Build up soil moisture reserve
• Pumping lifts may be less
• Deeper infiltration, less evaporation
• Reserve may help at harvest
• Appropriateness of winter irrigation
depends on several factors
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Ways to Reduce Energy Unit Cost
• Compare energy sources and costs
• When rainfall is low, winter irrigate?
• When more than one source of water is
available, look for opportunities to
coordinate them and save
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Steps to Reduce Horsepower Requirements
• Reduce pressure requirements
• Change from impact sprinkler (>50 psi) to drip
• Change from high to low pressure micro-irrigation
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Steps to Reduce Horsepower Requirements
• Reduce pressure requirements
• Operate efficient pumping plants
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Electrical Pumping Plant Efficiency
%
Efficiency
gpm x total head
=
3960 x Input Horsepower
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An Efficient Pumping Plant
• Provides enough total head to lift and
pressurize water
• Delivers enough flow capacity (gpm)
• Minimizes horsepower requirement
• Operates efficiently over expected range of
groundwater conditions
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100
TOTAL HEAD (feet)
Example Pumping Plant Performing as Expected
80
60
1984(54%)
1983 (64%)
1985 (62%)
40
20
0
2000
2400
2800
PUMP CAPACITY (gpm)
3200
3600
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Possible Reasons for Lower Pumping Plant
Efficiency Unrelated to Pump Wear & Tear
• Declining groundwater level that doesn’t match
pump performance characteristics
• Change in irrigation system requiring more water
or pressure
• Declining well efficiency
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100
TOTAL HEAD (feet)
Example Pumping Plant Not Performing as Expected
80
1983 (64%)
1984 (66%)
60
1985 (55%)
40
20
0
2000
2400
2800
PUMP CAPACITY (gpm)
3200
3600
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Corrective Actions
• > 60 % efficiency, no correction
• 55 to 60 % efficiency, first impeller
adjustment, second repair
• 50 to 55 % efficiency, first pump repair,
second replacement
• < 50 % pump replacement
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Steps to Reduce Horsepower Requirements
• Operate pumps that perform efficiently
• Maintain efficient pumping plants
• Well efficiency
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Keys to Reducing Water and Energy
Costs
• Minimize hours of irrigation or pumping
• Acquire energy at a competitive cost
• Reduce horsepower or kilowatt demand
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Don’t Let Irrigation Costs Sneak Up on You!
THANK YOU!
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