Cool Season Vegetables and Strawberry Response to ...holdenresearch.com/wp-content/uploads/2011/09/WPHA... · Holden Research and Consulting Cool Soils • Cool soils may induce phosphorus

Holden Research and Consulting

Cool Season Vegetables andStrawberry Response to Phosphates– Research and Observations over

the last Ten YearsDavid Holden



Introduction

• My Experience– Over 700 trials in the past ten years in nutrient

and pest management for fruit, nut, and vegetable production.

– Over 35 trials in the past ten years with phosphate based fertilizers on vegetables, strawberries, grapes, and trees.


Introduction

• All phosphate trials were conducted in the coastal counties of Monterey, San Luis Obispo, Santa Barbara, and Ventura

• Both ortho and poly – phosphates were involved.

• Sometimes “organic acid” additives were involved, along with phosphorus “protecting” products.


University Recommendations

University of California, ANR Publication 8098, Nutrient Management In Cool Season Vegetables


What are the Issues withPhosphorus Availability

• pH

• Temperature

• Cation inhibition– Calcium

– Zinc

– Etc.


How Soil pH affects P2O5


Cool Soils

• Cool soils may induce phosphorus deficiency

• With cool soils you have slower root growth and development

• Less opportunity for roots to come in contact with the phosphorus they need at this time

• Limiting phosphorus in cool seasons exacerbates the ability for cool season vegetables to grow.


Cation Inhibition

• Calcium and zinc cations (and others) have an affinity for PO4, phosphate anion.

• They form calcium and zinc phosphate precipitates which are now hard to resolubilize for root uptake.

• But this also helps reduce leaching of PO4

from the soil solution.


Plant Phosphorus Utilization

• Forms nucleic acids (DNA and RNA)

• Used in the making of the chemical energy molecules of ATP and ADP.

• Through this transfer of chemical energy it is utilized in new growth and reproduction.

• Note that dry leaf analysis of P2O5 in young leaves is always higher than that found in older leaves.


Symptoms of PhosphorusDeficiency

• Slow growth, stunted plants

• Purplish coloration on foliage of some plants (older leaves first)

• Dark green coloration

• Delayed maturity

• Poor fruit or seed development


Not So Obvious Symptoms ofPhosphorus Deficiency

• Poor root development

• Reduced production– Sizing reduction

– Fruit set reduction



Phosphate vs. Phosphite orPhosphoric Acid vs. Phosphorous

Acid• One is the source for a fertilizer, the other is

a source for a fertilizer and a fungicide.

• PO4 vs. PO3. PO3 will (?) oxidize eventually to PO4

• Know the difference. There is still quite a bit of confusion regarding these source products


Four Recent Trials withPhosphates in Peppers and

Strawberries.• Phosphates generally placed in addition to

the grower’s standard practices which may include pre-plant and in-season phosphate applications.

• All crops grown on tape, which allows for precise in season placement of phosphate.


Early Spring 2010 Peppers

• Pre-Plant poly phosphate applied as band under seedline on 4/27/10

• Pre-Plant Phosphorus (Olsen Method) – 41 ppm

• Treat 1 – untreated

• Treat 2 – 100 lb/ac P2O5 as 10-34-0

• Treat 3 – 55 lb/ac P2O5 as Proprietary

• Treat 4 - 30 lb/ac P2O5 as Proprietary

• Planted 5/5/10


Lbs./Plant

UTC 1.6

Reduced Propietery 2 1.6

Reduced Propietery 1 1.8

Grower Standard 2.3

0.0

0.5

1.0

1.5

2.0

2.5

Po

un

ds

of

Fru

it

Chart 1: 2010 Spring - Summer Bell Pepper Phosphate Study -Camarillo, CA. - Total Yield per Plant

b

a

bab


Post Treat Soil P2O5 Levels

• Treat 1 – 30 ppm





Late Spring 2010 Peppers

• Pre-Plant poly phosphate applied as band under seedline on 6/17/10

• Pre-Plant Phosphorus (Olsen Method) – 44 ppm

• Treat 1 – 125 lb/ac P2O5 as 10-34-0

• Treat 2 – 100 lb/ac P2O5 as 10-34-0

• Planted 6/20/10


Lbs./Plant

100 lb P2O5 2.1

125 lb P2O5 2.2

0.0

0.5

1.0

1.5

2.0

2.5

Po

un

ds

of

Fru

it

Chart 2: 2010 Late Spring - Summer Bell Pepper Phosphate Study -Camarillo, CA. - Total Yield per Plant


Post Treat Soil and Leaf P2O5

Levels• Treat 1 – 40 ppm


• Leaf Treat 1 - .32%

• Leaf Treat 2 - .35%


2008-09 Strawberries• Planted 10/2/08

• All Received Pre-Plant and in-Season Phosphate

• 500 lb/ac 18-8-13 slow release

• Approximately 20 gal/ac Phosphoric acid in season (150 lb P2O5) in tape

• Experimental Treatment received another 80 lb/ac of P2O5 in the tape and 40 lb/ac of P2O5

foliar as Proprietary Product


Plant Sizing at Nine Weeks afterPlanting

Grower Standard

Additional Phosphate


0.0

500.0

1000.0

1500.0

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3500.0

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5000.012

/8/0

8

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09

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/09

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/09

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/09

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/09

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/09

Tra

ys

pe

r Ac

re (

10

lb

. e

qu

iva

len

t)

Pick Day

Chart 6: Proprietery 2008-09 Strawberry Nutrient Study - Camarillo, CA. - Cumulative Marketable Production by Pick Day

Grower Standard

Proprietery


0.0

200.0

400.0

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1200.012

/8/0

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/09

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/09

Tra

ys

pe

r A

cre

(1

0 l

b.

eq

uiv

ale

nt)

Pick Day

Chart 6: Proprietery 2008-09 Strawberry Nutrient Study - Camarillo, CA. - Early Cumulative Marketable Production by Pick Day

Grower Standard

Proprietery

155 flats ahead


0.0

500.0

1000.0

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09

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/09

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/09

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Tra

ys

pe

r A

cre

(1

0 l

b.

eq

uiv

ale

nt)

Pick Day

Chart 6: Proprietery 2008-09 Strawberry Nutrient Study - Camarillo, CA. - Late Cumulative Marketable Production by Pick Day

Grower Standard

Proprietery

57 flats behind


Conclusions

• Additional Early Season applications of P2O5 did help increase early season production

• As soils warmed and crop finished out the end season differential was not as great

• Early season production does return the grower a better price per flat.


2009-10 Strawberries• Planted 10/3/09

• All Received Pre-Plant and in-Season Phosphate

• 500 lb/ac 18-8-13 slow release

• Approximately 20 gal/ac Phosphoric acid in season (150 lb P2O5) in tape

• Experimental Treatment received another 45 lb/ac of P2O5 in the tape as 3-18-18 (ortho phosphate) over five applications

• Also Proprietary product run alone and in combination with 3-18-18


Plant Sizing at Nine Weeks

Grower Standard

Product A

3-18-18/Product A

3-18-18


0.0

1000.0

2000.0

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6000.0

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4/20

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/201

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1 2 3 4 5 6 7 8 9 10 11 12 12 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

Tra

ys

pe

r A

cre

(1

0 lb

. e

qu

ival

ent)

Pick Day

Chart 8: Proprietery Trial on Strawberries - Ventura County, Fall/Winter 2009-2010 - Cumulative Marketable Production by Pick Day

Product A/3-18-18 Product A Alone Grower Standard 3-18-18 Alone


0.0

100.0

200.0

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Tra

ys

pe

r A

cre

(1

0 l

b.

eq

uiv

ale

nt)

Pick Day

Chart 8a: Proprietery Trial on Strawberries - Ventura County, Fall/Winter 2009-2010 - Cumulative Marketable Production by Pick Day



0.0

1000.0

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/201

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14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

Tra

ys p

er A

cre

(10

lb. e

qu

iva

len

t)

Pick Day

Chart 8a: Proprietery Trial on Strawberries - Ventura County, Fall/Winter 2009-2010 - Cumulative Marketable Production by Pick Day



-$2,500.00

-$2,000.00

-$1,500.00

-$1,000.00

-$500.00

$0.00

$500.00

$1,000.00

$1,500.00

$2,000.00

$2,500.00

12/1

4/20

09

12/1

7/20

09

12/2

2/20

09

12/2

7/09

12/3

0/09

1/4/

10

1/8/

2010

1/11

/201

0

1/15

/201

0

1/18

/201

0

1/22

/201

0

1/25

/201

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/201

0

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2010

2/4/

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2010

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/201

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/201

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/201

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2010

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/201

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3/15

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/201

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3/22

/201

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/201

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4/2/

2010

4/5/

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4/9/

2010

Do

llars

pe

r A

cre

-G

ros

s (

do

es

no

t in

clu

de

co

st

of

pro

gra

m

Pick Day

Chart 9:Proprietery Trial on Strawberries - Ventura County, Fall/Winter 2009-2010-Cumulative Differential from Grower Standard Return

Product A/3-18-18 Product A Alone 3-18-18 Alone


Conclusions

• Additional Early Season applications of P2O5 did help increase early season production

• Spring of 2010 was cooler than previous spring. With phosphate source removed in February, reduction in production was observed.


General Conclusions

• General production increases of 5-10% for coastal vegetables and strawberries when additional phosphate added to the growers standard programs in the fall, winter and early spring.

• These have occurred on soils that are not generally P2O5 deficient. 40-100 ppm P2O5 soils

• Similar results not observed in the summer time.

• No surprise that we are seeing a response on colder soils

• It is a surprise that what the grower’s thought was sufficient supplies of phosphorus was not so.


Thank You!

Documents

Cool Season Vegetables and Strawberry Response to ...holdenresearch.com/wp-content/uploads/2011/09/WPHA... · Holden Research and Consulting Cool Soils • Cool soils may induce phosphorus