Supercharging your P fertilizer – Does it

Work?

Cynthia Grant, Cynthia.grant@agr.gc.ca

Phosphorus

• Phosphorus is critical for crop growth

– Structural component of nucleotides, nucleic acids and phospholipids.

– Essential for all energy reactions

– Needed for all growth processes

– Promotes root development, tillering, early flowering, seed production, and uniform ripening.

• P fertilizer is a major input for crop production on the Canadian prairies

• Low P recovery is a major economic and environmental concern

How Much Phosphorus is Needed by a Crop?

• A 45 bu/acre spring

wheat crop removes

about 24 lb P2O5 per

acre

– About 10 lb more taken up

but recycled in residue

– Total of about 34 lb needed

for growth

– 40 bu/acre canola removes

38 and needs around 58 lb

for growth

Without an adequate P supply,

crop yield will be reduced

-input and off-take should be

balanced over time to avoid

excess or depletion

-not all crop requirement has

to come from fertilizer in each

year

Plants Access P from Soil Solution

Soil solution

phosphorus

HPO4-2

H2PO4-2

Fertilizer additions make up

the difference between crop

demand and soil supply

Products and practices that attempt to improve

P use efficiency

• Banding P near the seed

• Use of more crop available forms

– Fluids versus dry

– Orthophosphates versus polyphosphates

• Reduce soil reactions

– Avail

• Release P gradually to match plant uptake

– Coated MAP

• Fungi that mobilize P in rhizosphere

– Provide Penicillium bilaii

• Fungi that improve plant access to P

– Mycorrhizae

5

How efficiently is P fertilizer used in wheat

systems on the Canadian prairies?

• It is estimated the P use efficiency in the year of application is generally less than 30%

• What happens to the other 70%? – Lost by run-off or erosion?

– Converted to other forms of varying solubility?

– Incorporated into the soil organic matter or microbial biomass?

– Used by subsequent crops?

• Can we use our P fertilizers more efficiently?

0

20,000

40,000

60,000

80,000

100,000

120,000

140,000

1965

1970

1975

1980

1985

1990

1995

2000

2005

P2O

5 (t

on

nes)

Source: Johnston 2006

P Added

P Removed

On a long-term basis, crop removal and replacement of P

seem to be relatively well-balanced

Indicates about 80%

recovery over time

Manitoba

1965-2006

Timing of supply is important for crop yield response

Phosphate

Fertilizer

Soil

Solution P

Mineral

Surfaces

Secondary

Ca and Mg or

Fe and Al

phosphates

Primary

Minerals

(Apatite)

Plant Uptake

Lower

Availability

Soil P Reactions Reduce P Availability

Principles of Phosphorus Nutrition that Affect

Fertilizer Management Choices

• Soil will supply P to the crop – Fertilizer “tops up” soil supply for optimum yield

– P availability varies with environmental conditions

• P is needed early in growth – Plants must have adequate supply in first 3-6 weeks

– Soil supply may be too low early in the season

– Need to apply starter at or before seeding

• P is not very mobile – Ties up with Ca, Mg, Al and Fe

– Doesn’t move far in the soil

– Roots must intercept P since P won’t move to roots

Phosphorus is Relatively Immobile in the Soil

Has important effect

on P management

decisions

Phosphorus Should be Banded

• Banding slows tie-up of P in soil – Having ammonium N in the band slows reactions further

– MAP, DAP and APP are effective P sources because they

contain ammonium

• Adding urea to MAP bands increases fertilizer P

uptake when fertilizer is banded away from seed

– However, excess N can delay P uptake due to band toxicity

Phosphorus Should be Banded

• Some plant roots proliferate in bands

• Ammonium in the band may also increase root

proliferation

• Uptake increases with P concentration and

rooting – Fertilizer bands provide high concentration

– More roots in the band increase uptake

Banding P Near the Seed-Row Ensures that Roots Will

Contact the P Granule Early in Growth

Broadcast Banded

At 25 Kg P2O5/Ha and 18 cm row

spacing have a granule every 2.3

cm (11-55-0)

The large difference between banded and broadcast

applications is POSITION

Courtesy Geza Racz

Banding P Near Seed is Most Important With

• Low soil P levels

• Restricted rooting

– Compaction

– Tillage pans

• Cool soil conditions – Solubility, mobility, rooting

– Early seeding

Fall band 70-30-10-10 on whole field

+10 lb/ac Seed

row P2O5

Pop-Up Effect from Seed Row P

Photo: Aaron Baldwin, Cargill

No starter P

Banding Reduces the Rate of P Needed

1.0

1.5

2.0

2.5

3.0

Gra

in Y

ield

(T/h

a)

0 10 20 40 80

Phosphate (kg/ha)

Broadcast

Banded

Westco Training Manual

20 band was as good

as 80 broadcast

Low P Mobility Limits How Much You Can Reduce P

Application Rates

• Must have a high enough rate that each

seedling can reach granule (or droplet)

during early growth

• Reducing rate below about 15-20 lb/acre

may restrict availability

• Distribution is affected by row spacing and

band width

– Greater the seed-bed utilization, the wider

apart the granules are spaced

– May need higher rate with higher seed-bed

utilization

Wheat - 7” rows, 5 lb/a P2O5

10 lb/a MAP fertilizer

7.6” between MAP particles

Wheat - 7” rows, 10 lb/a P2O5

19 lb/a MAP fertilizer

3.8” between MAP particles

Dry Fertilizer Material

Wheat - 7” rows, 15 lb/a P2O5

29 lb/a MAP fertilizer

2.5” between MAP particles

Wheat - 7” rows, 20 lb/a P2O5

38 lb/a MAP fertilizer

1.9” between MAP particles

Dry Fertilizer Material

Wheat – 7” rows, 5 lb/a P2O5

1.25 gallons/acre 10-34-0

11.2” between drops of fertilizer

Wheat – 7” rows, 10 lb/a P2O5

2.5 gallons/acre 10-34-0

5.9” between drops of fertilizer

Liquid Fertilizer Material

Wheat – 7” rows, 15 lb/a P2O5

3.75 gallons/acre 10-34-0

3.7” between drops of fertilizer

Wheat – 7” rows, 20 lb/a P2O5

5.0 gallons/acre 10-34-0

2.8” between drops of fertilizer

Liquid Fertilizer Material

Can different formulations improve P

availability?

• Monoammonium phosphate is the standard fertilizer source for the prairies

– Ammonium in formulation enhances efficiency

• Ammonium polyphosphate is standard fluid form

• Other novel formulations include:

– Fluid orthophosphates such as Alpine

– Avail additive

– Polymer coated MAP

Fluids Versus Dry

• Under highly calcareous conditions in

Australia, fluid forms of P are more available

than dry

– Water moving toward granule carries Ca

– Ca precipitates P and leads to small reaction

zone

– Fluid forms increase reaction zone and allow

greater root uptake

• Similar benefit has not shown up in tests in

Manitoba

There was no difference between dry MAP and fluid APP in

wheat yield over three years at two sites near Brandon

• Similar results in

previous studies by

Racz and in later

studies on wheat and

soybean

• Soils are much less

calcareous than the

70% calcium carbonate

in the Australian trials

Orthophosphates versus Polyphosphates

• Polyphosphates are chains of orthophosphates

• Most polyphosphate fertilizers still have 40-60% of the phosphate in the orthophosphate form

• Polyphosphate converts to orthophosphate in soils rapidly

– Half usually is converted within a week,

– Conversion may be slower if soils are cool and dry

• Generally no difference in effectiveness under field conditions

– http://www.extension.umn.edu/distribution/

cropsystems/DC6288.html

In studies by Tom Jensen at Brandon, 10-34-0 and MAP performed

as well or better than enhanced P products (Average of 8, 16 and 32

kg ha-1 phosphate rates)

41.2

39.2

38.2 38.1

37.2

35.7

38.5

38.0

32

33

34

35

36

37

38

39

40

41

42

Grain

yie

ld, b

u/a

cre

10-34-0 Simplot 7-

25-6-4

MAP or 11-

52-0

Omex 10-34-

0 plus TPA

Alpine 6-22-4 Alpine 6-24-6 AVAIL No AVAIL

a

b

ns

Some Enhanced Efficiency P Fertilizers Being Evaluated

• Avail – Maleic Itaconic Copolymer

– Similar technology to Nutrisphere

– Complexes Ca, Mg, Fe and Al

– Reduces fixation of P

– Limited data under prairie conditions

In studies by Tom Jensen at Brandon, yield was similar with MAP

alone or treated with Avail

41.2

39.2

38.2 38.1

37.2

35.7

38.5

38.0

32

33

34

35

36

37

38

39

40

41

42

Grain

yie

ld, b

u/a

cre

10-34-0 Simplot 7-

25-6-4

MAP or 11-

52-0

Omex 10-34-

0 plus TPA

Alpine 6-22-4 Alpine 6-24-6 AVAIL No AVAIL

a

b

ns

Wheat (6 site-years)

- Avail

+ Avail

22

24

26

28

30

32

34

0 10 20 30 40

Phophorus rate, lb P2O5/acre

Gra

in y

ield

, b

u/a

cre

Karamanos

In wheat on the prairies, yield was similar if

MAP was applied with or without Avail

Application of Avail-treated MAP produced the same

potato yield as side-banded MAP

f

e

abc ab

bc de

Gaia Consulting

Portage and Carberry 2007 to 2009

350

360

370

380

390

400

410

420

Pota

to Y

ield

(cw

t/acr

e)

Control

Sideband 20

Sideband 40

Sideband 80

Avail 40

Broadcast 40

Avail did not improve grain yield over MAP over three years at

two sites near Brandon

• No difference among

treatments

• All products performed

the same if banded

Coated Enhanced Efficiency P Fertilizer is Being Evaluated

• Polymer coated monoammonium phosphate – Same technology as ESN

– MAP is gradually released into soil solution

– Matching release to crop uptake should reduce fixation

– Can also reduce risk of seedling damage

– Limited testing so far

Neither the coated MAP nor the Avail improved grain yield over

MAP or APP over three years at two sites near Brandon

• No difference among

treatments

• All products performed

the same if banded

Novel formulations have not shown yield

benefit in most independent studies

• Fluids, MAP, orthophosphate and polyphosphates,

Avail-treated and coated products performs similarly

• Important to band an adequate amount near seed-row

• Ensure P is available early in the growing season

• Balance P rate with removal over time to avoid

depletion

34

What about the microbial products

• Two major products sold in western Canada

• Provide (Jumpstart and part of Tagteam)

• Mycorrhizal inoculants

35

Provide is a microbial inoculant

• Penicillium bilaii (also classified as P. bilaji and P.

bilaiae) is a fungi that colonizes the rhizosphere

• Effective in solubilizing phosphorus (P) under

controlled conditions

• Under field conditions, results have been mixed

36

On P responsive sites with durum wheat, Provide did not increase yield as

compared to the untreated control at nine site-years in Manitoba and Alberta

• Adding Provide alone was

equal to the untreated

control

• Adding Provide plus 10 lb

of phosphate gave yield

response of about ½ of

applying 20 lb of

phosphate

• Significant yield increase

with P but no significant

benefit of provide

20

30

40

50

60

Gra

in Y

ield

(bu

acre

-1)

Mean Minnedosa

Control

Provide aloneProvide + 10 lb P

20 lb P40 lb P

Grant et al. (2002)

Flax Yield Did Not Respond to Either Side-banded P

or Provide in Nine Site-Years in Manitoba

0

5

10

15

20

25

30

35

Gra

in Y

ield

(bu

acre

-1)

Brandon Minnedosa Rosebank

Control

20 P

Provide

Effect of P. bilaii and P fertilizer on wheat and barley

barley grain yield

60

80

100

120

140

160

0 9 18 27

P Rate (kg/ha)

Barl

ey Y

ield

(B

u/a

cre

)

P alone

P + P.bilaii

Karamanos

35

40

45

50

55

60

0 9 18 27

P Rate (kg/ha)

Wh

ea

t Y

ield

(B

u/a

cre

)

P alone

P + P.bilaii

47 site years – 20 site years

Mycorrhizal Association May Improve P Availability

• Mycorrhizae are an association between plant roots and a fungus – Especially important for flax and corn

– Do not occur with canola or sugar beet

– Mycelium grows into the soil and increases area mined for nutrients

• Fungi gives nutrients to plant and plant gives sugars to the fungi

• Mycorrhizae are reduced by: – Tillage

– Summer fallow

– P fertilization

– Following a nonmycorrhizal crop

Plant Root

Benefit of Inoculation with Mycorrhizae Uncertain

• Inoculation with mycorrhizae not widely tested in field conditions

• Native mycorrhizae exist naturally in soils

– Inoculation may not be needed under many conditions

• Some crops are more dependant on mycorrhizae

– Flax or corn versus wheat

• Crop “pays” mycorrhizae with photosynthate – If cost is greater than benefit, AM may decrease

yield

In nine site-years in Manitoba and Alberta colonization in

wheat roots was increased by inoculation and reduced by P

0

5

10

15

20

25

30

-Co

lon

iza

tio

n-

%

Lacombe MCDC Maziers

P Fertilizer

Control

Myc

*

*

*

0.0

0.4

0.8

1.2

1.6

Bio

ma

ss Y

ield

(T

ha

-2)

Lacombe MCDC Maziers

Control

P Alone

Mycorrhiza

Mycorrhiza + P

**

Biomass at Six Weeks Tended to Decrease

with Mycorrhizal Inoculant

Biomass yield at heading also tended to decrease

with inoculation

*

Mycorrhizal Inoculation Did Not Affect Wheat Grain

Yield in Nine Site Years in Manitoba and Alberta

Inoculant tended to reduce grain yield at Philips in 2005

10

15

20

25

Gra

in Y

ield

(bu

acre

-1)

Control

MAP S

B

CRP SB

APP SB

APP Drib

.

No Myc. Myc

• Yield was higher with P

fertilizer than inoculant

alone

• Grain yield was reduced

at Philips when

inoculant was added

with fertilizer

Effect of mycorrhizal inoculation

• Mycorrhizal inoculation increased colonization – Tended to decrease early biomass

production

– No benefit on final grain yield

– Sometimes led to a small decrease in yield

• Mycorrhizae may “cost” wheat more than they contribute

• Need more information on other crops

– Effect may differ with flax

Summary

• P use efficiency in the year of application can be low

– 25 to 30%

• P reacts in the soil to forms that are less available than

original fertilizer

– However plants can still access this P in following years

48

Summary

• Banding starter P placed close to the seed is important

to optimize crop yield

• Cutting rate too low may not place P close to each seed

• Little difference between MAP and other new

formulations under Manitoba conditions

– Fluids vs dry

– Orthophosphates vs polyphosphates

– Avail treatments

– Polymer coating

49

Summary

• Provide does not appear to be highly beneficial under

field conditions

• Inoculation with mycorrhizal spores can increase

colonization in wheat

– Does not lead to yield increase

– May decrease yield under some conditions

• Inoculation needs more testing with mycorrhizal-

dependent crops like flax

50

Summary

• Crop removal of P is fairly well balanced with P addition

in non-manured fields

• P use efficiency may be higher than we think

• Cutting application rates to less than crop removal may

not be desirable

– Too little P for plant roots to physically access

– Long-term depletion of soil P

– Crop productivity is lower on P depleted soils

• Band an available form of P near the seed row at rates

that reflect crop removal over the cropping sequence

51

Thank You

For your

Attention