Maziar M. Kandelous (mkandelous@ucdavis.edu)

Barzin A. Moradi

Optimization of water and nitrate application efficiency for Citrus trees: recommendations for irrigation and

fertigation practices

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Background Information

• What do we do (Objectives)?

• Why do we do what we do (The importance of the work)?

• How do we do (Methodology)?

• Who get benefits from what we do (Benefit to Citrus Industry)?

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• Monitor the water and fertilizer application

• Monitor the water and fertilizer leaching

• Find possible solutions for the discovered issues

• Provide recommendation to help farmers

maintaining/improving the yield while following the regulation

Objectives

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Application

• How much water we apply? Is it uniformly distributed?

• How much nutrient we apply? Is it uniformly distributed?

• What is the evapotranspiration demand? Is it uniform?

CIMIS stations

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Leaching

•Water Balance

•Darcy Law

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Water Balance

StorageinChangepirationEvapotrans

ionPrecipitatIrrigationLeaching

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Water Balance

Cu

mu

lati

ve le

ach

ing

(cm

)

16 in

-12 inSIZE: IRRIGATION WATER, 194<IW<222 COLOR: LEACHING, -12<L<16

DripFanjet

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Darcy Law

BA

AB

Z

HHK

Leaching

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Darcy Law

Total head gradient

BA

AB

Z

HH

10

Darcy Law

hh

Total head gradient

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Darcy Law

Total head gradient

40cm

A B

q

12

Darcy Law

fKK s

Soil hydraulic conductivity

13

Darcy Law

<Soil #1Soil #2

sK

14

Darcy Law

fKK s

1f 2f

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Darcy Law

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Just an example

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Darcy Law

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Study Site

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Results - Mandarin

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Results – Orange

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Benefit to Citrus Industry

• Self-monitoring of water/nitrate leaching

• Monitoring of soil profile water status

• Site dependent irrigation management

• Site/Crop dependent fertigation management

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How will industry implement your results

• Citrus grower as end user will have better understanding of managing their farm and improve it (if indeed needed)

• This study will result a guideline on how to use the available technologies to better manage each specific orchard?

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One thing to remember

• No one should tell you that you need to eliminate your leaching

• Based on the quality of water you have you are required to add more water than required to leach the salt out of root zone

• You just want to make sure that you have no nutrient (Nitrate) in your leaching water