Open Hydroponics – An Approach for Greening

Pete Spyke

Arapaho Citrus Management, Inc.

What is OHS?

Elements:

Drip irrigation

Close spacing

Fertigation

Canopy Mgmt

Intensive mgt.High yieldsEarly $$

One approach to Greening• New grove goals:

– Reach breakeven ASAP;– Improve overall income – Improve greening mgt. – Outrun tree losses!

• Mature grove goals:– None – infection spreading too fast

WATER

• Calculated for daily applications based on root growth, ET, and canopy development.

• Apply in pulses.• Minimize effort for

uptake.• Good root aeration.• Salinity Management.

CROPPING

• Occurs naturally in 2 years, or

• Enhanced with girdling.

• Heavy Cropping aids in Tree Vigor Control

NUTRIENT MANAGEMENT

• Fertigate to provide non-limiting conditions

• Amount of nutrients directly related to tree growth.

• Proportions according to annual growth cycles (phenology).

• Salinity Management

• No Florida Recommendations!

Close spacing/Tree precocity

• Conventional grove: 15 x 25 ft.

(116 trees/acre)

• Modern grove: 10 x 20 ft

(218 trees/acre)

• High density grove: 8 x 15 ft

(363 trees/acre)

Lemon/RL planted 1999 @ 5 x 16 ft. Trees were planted on shallow ridges and produced ~140 boxes/acre @ 14 months, 500 @ 36 months and 800 in 2005.

Will the system work…….in Florida?

– Sandy soil– Florida rainfall vs. root concentration– How is this system different from what

we are already doing?– General economics.– Fruit quality.– Excessive flushing?

Rock Bottom OHS/APS Comparisons

• 10 acre grove in Ft. Pierce

Cooperators – Dr. Bill Castle & Japie Kruger

Rock Bottom OHS/APS Comparisons

• Ray Ruby, Rio Red, Flame Grapefruit, and Minneola – Gpft 11/06, Minneolas 2/07

• Minneola Rootstocks:– Sun Chu Sha– Swingle– Gou Tou

• Grapefruit rootstocks:– Smooth Flat Seville– Flying Dragon Trifoliate– Cleopatra Mandarin– X639– US 897

• Tree spacing 6 and 8 feet in 20’ rows (363 and 272 trees/acre)

• Drip vs. Microjet

• Winder/Chobee soils

• Saline canal water

• Greening all around

Rock Bottom OHS/APS Comparisons

January 2007 – 2 months after Planting

Drip - Ray Ruby/SFS @ 9 Months

Microjet – Ray Ruby/SFS @ 9 Months

Granular Slow Release Fertilizer, plus run

system every day with liquid fertilizer

Question:• Will Roots Cluster Under Emitters?

•Keep roots bathed in nutrient solution

• Rapid uptake of injected materials

• Moisture stress management

Questions:

• Can we control tree size?– Rootstocks– Pruning– Fruit– Tree

Manipulation– Flowering

Control

Questions:• What is the best

spacing?• Canopies touching in

row @ 24 months = 1st crop as high as possible

Minneola/Gou Tou @ 6’Ray Ruby/FD @ 8’

Spacing will be scion/rootstock/soil dependent.

Questions:

• Profitable?– Higher cost/acre for establishment– Much lower cost/tree than “conventional” =

earlier operating profit– Lower irrigation, fertilization, weed control,

routine labor costs– Higher pruning costs– High production in early years – 80% Less Water and Fertilizer Year 1 & 2 –

CHEAP!

Experiments Under Way

• Rock Bottom – Dr. Bill Castle and Pete• SWFREC – Dr. Kelly Morgan• CREC, Gapway Groves – Dr. Arnold

Schumann• USDA Picos Road – Dr. Ed Stover• Conserv – Drs. Castle, Parsons, Morgan• More planned – GeoSpider? -- Looking good so far --

Why?

• Whatever the solution to Greening, it will involve new groves

• Valid approach even with current knowledge base

• Early profit will be primary motivator to re-establish the industry

It’s Possible! Needs More Work!

ArapahoCitrus.com