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How Does Canola Get Its Nutrients?

C.A GrantAgriculture and Agri-Food Canada

Brandon Research Centrecgrant@agr.gc.ca

N CaP Mg

K S

17EssentialElements

17EssentialElements

Canola Needs a Total of 17 Elements

C H O

B Cl Cu FeMn Mo Zn Ni

N CaP Mg

K S

17EssentialElements

17EssentialElements

Some come from the air or water

C H O

B Cl Cu FeMn Mo Zn Ni

N CaP Mg

K S

17EssentialElements

17EssentialElements

Others are usually present in adequate amounts in prairie soils

C H O

B Cl Cu FeMn Mo Zn Ni

N CaP Mg

K S

17EssentialElements

17EssentialElements

N, P and S are most often limiting for canola production

C H O

B Cl Cu FeMn Mo Zn Ni

Nitrogen is Critical for Crop Growth

• Usually most limiting nutrient

• Largest fertilizer input• Required for optimum

yield and protein

How Much Nitrogen is Removed by a Canola Crop?

• A 40 bu/acre canola removes about 85 lb N per acre

• About 40 lb more taken up but recycled in residue

• About 125+ needed for growth

Daily Uptake of N By Canola Reaches 6 to 8 lb per acre per day About 6-8 Weeks after Seeding (6 leaf stage)

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7

3 4 5 6 7 8 9 10 11 12 13 14 15Weeks after Seeding

N u

ptak

e ra

te, l

b N

/acr

e/da

y

0

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Biom

ass accumulation rate,

lb/acre/day

6 le

af s

tage

Carstairs

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3 4 5 6 7 8 9 10 11 12 13 14 15

Weeks after Seeding

N u

ptak

e ra

te, l

b N

/acr

e/da

y

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Biom

ass accumulation rate, lb/acre/day

Bud

ding

sta

ge

6 le

af s

tage

Olds

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Weeks after Seeding

Nitr

ogen

upt

ake

rate

, lb/

acre

/day

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140B

iomass accum

ulation rate, lb/acre/day

6 le

af s

tage

Rosser

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3 4 5 6 7 8 9 10 11 12 13 14

Weeks after Seeding

Nitr

ogen

upt

ake

rate

, lb

N/a

cre/

day

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Biom

ass accumulation, lb/acre/day

6 le

af s

tage

Petersfield

(Courtesy Rigas Karamanos)

Mineralization

Immobilization

Plants Access N from Soil

Nitrate and ammonium in solution and on exchange

Fertilizer additions make up the difference between crop demand and soil supply

Nitrogen Reactions Influence Availability from Soil and Fertilizer

AmmoniumNH4

+

46-0-082-0-0

28-0-0 (75%)

Manure &Crop Residues

NitrateNO3

-Soil Organic N

Leaching & runoff

N2, N2O Denit’n

NH3Volat’n

Immobilization

AmmoniumNH4

+

46-0-082-0-0

28-0-0 (75%)

Manure &Crop Residues

NitrateNO3

-Soil Organic N

Leaching & runoff

N2, N2O Denit’n

NH3Volat’n

Immobilization

AmmoniumNH4

+

46-0-082-0-0

28-0-0 (75%)

Manure &Crop Residues

NitrateNO3

-Soil Organic N

Leaching & runoff

N2, N2O Denit’n

NH3Volat’n

Immobilization

NO

Crop Removal

Mineralization

Reactions and Losses Depend on Environment and Management

• Nitrogen losses can be high, with poor management or under bad conditions

• Management practices can be used to minimize losses

Volatilization can be high with broadcast urea if not incorporated

Fertilizer N

NitrateNO3

-

AmmoniumNH4

+

Leaching, runoff

Denitrification

N2NO N2O

Nitrification

NH3

volatilization

40-90% of urea-N under hot, dry conditions

Banding Reduces Ammonia Losses to Extremely Low Levels

0

100

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500

Am

mon

ia (g

N h

a -1

)

Fall Spring pre-seeding

After Seeding

CT-ControlCT-UncoatedRT-ControlRT-Uncoated

• If urea bands were sealed, losses were no higher than from the control – grams per hectare

• Some losses occurred under RT when band did not seal

Brandon ZTF

Leaching can be high on sandy soils with excess rain or irrigation

Denitrification can be high on warm, saturated soils

Fertilizer N

NitrateNO3

-

AmmoniumNH4

+

Leaching, runoff

Denitrification

N2

NO N2O

Nitrification

2-4 lb N/ac/day under saturated soil conditions

Banding an Ammonium-Producing Source Reduces Leaching and Denitrification Losses

• Ammonium must convert to nitrate before it is susceptible to loss– Slows conversion of ammonium to nitrate– Lowers nitrate concentration in the solution– Reduces the risk of loss

r = 0.66*

r = 0.11ns

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120

10-Sep 20-Sep 30-Sep 10-Oct 20-Oct 30-OctDate of application

Gra

in y

ield

(% o

f spr

ing)

Highs Lows Linear (Lows) Linear (Highs)

Thiessen et al. – U. of Manitoba

Supported by data from U. of Manitoba that showed losses from fall-banded N fertilizer were minor on well-drained soils

Soil freezesCrop

harvest

Upper slope

Lower slope

Much of our N “Loss” may be Cycling via Immobilization-Mineralizationimmobilization - “tie up of N”mineralization - “release of N”

-15

-10

-5

0

5

10

133 159 181 202 222 251

Sampling date

N m

iner

aliz

ed (k

g/ha

)

Durum Stubble Pea Stubble

May

13

June

8

June

30

July

21

Aug

10

Sept

8

N tie-up N release

Selles

In-Soil Banding Reduces Immobilization

0102030405060708090

100

straw incorp N bcst

straw on surfaceN bcst

straw removed N bcst

straw incorp N band

straw on surfaceN band

straw removed N band

Rec

over

y of

fert

ilize

r N %

Immobilized NPlant N

Tomar and Soper, 1981

Fall recovery of fertilizer N in crop and soil

Immobilized Nitrogen is not a “Loss”

• Builds soil organic matter• Improve soil quality • Cycles back to following

crops– Improves soil’s ability to “buffer”

N supply in years when yield potential is high

• Need to consider both soil nitrate and mineralization to predict soil N supply

Mineral N

Soil Testing For Available N

• Provides indication of residual nutrient in soil– Nitrate “in the bank”

• Does not necessarily consider mineralization– “Interest on organic matter”

Older Systems May Rely More on Stored Soil Nitrate

• Soil nitrate released and stored over fallow period– “Mine” organic matter to

release N

• Intensive tillage increases mineralization and amount of nitrate in soil at seeding

• Continuous cropping and reduced tillage reduce the stored nitrate

• N fertilization and higher yield increase residue return to the soil

• May increase the importance of N mineralization from SOM and crop residues over the growing season

Can We Test for Mineralization?

• Specific tests predict “potential mineralization”– “Mason Jar test”– Long-term incubation – Have not been very useful so far in the prairie

environment for routine testing

• Tests measure release under ideal temperature and moisture

• Actual mineralization depends on environmental conditions

Potential Mineralization Increases with Soil Organic Matter Content

• More organic matter gives more potential for N release under the right conditions– Acts as “buffer” for N rate– Conditions that promote high

crop yield promote N release– As crop demand increases,

the ability of SOM to release N increases

y = 43.02x - 26.958R2 = 0.5375

0

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300

0 1 2 3 4 5 6

Soil Organic C (%)

Pot M

in N

(ppm

)

Past Management Can Affect N-Supplying Power of the Soil

Long-Term Building• Continuous Cropping • Diversified Crop Rotation

(cereal-oilseed- cereal-pulse)• Good N fertilization• Some forages before start of

zero tillage (1978-1983)• As of 2008, 30 years of no-till

Long-Term Depleting• 50/50 summerfallow/crop

rotation prior to 2001• Minimal N fertilizer• Conventional tillage• Crop Rotation (cereals

mainly)• No-till since 2001

Courtesy of Guy Lafond

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60

0 30 60 90 120

Nitrogen (kg/ha)

Yie

ld (b

us/a

cre)

BuildingDepleting

Spring Wheat (3 years) – Grain Yield

~30 kg/ha

How to Improve Nitrogen Use Efficiency?• Soil nitrate test is still a good indicator of

available N for crop growth in annual cropping systems

• Improve estimates of soil N supply to fine-tune application rates in modern systems

– Consider past inputs of legumes, manures and other soil building practices– Modelling or measurement of mineralization

• Match management practices to environment– Select proper rate, source, timing and placement of N fertilizers– Enhanced efficiency fertilizers and split applications may have role where

environmental conditions promote losses

• We may be underestimating nitrogen use efficiency if we don’t consider N balance over the long-term

Canola has a High Demand for P

Adequate P is needed for full response to N fertilizer

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N (kg/ha)

Yiel

d (t/

ha)

0 20 40 60 80P2O5 kg /ha

Hybrid Canola

Westco

29

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– Need to apply 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

30

How Much Phosphorus is Needed by a Crop?

• 40 bu/acre canola removes 38 lb/acre

• Additional 20 lb/acre is cycled in the residue

• Total of around 58 lb for growth

Without an adequate P supply, crop yield will be reduced

But not all crop requirement has to come from fertilizer

31precipitation

Plants Access P from Soil Solution

Soil solutionphosphorus

HPO4-2

H2PO4-2

Fertilizer additions make up the difference between crop demand and soil supply

dissolution

Mineralization

Immobilization

weatheringAdsorption

desorption

Factors that Restrict P Availability

• Low soil P reserves (soil test P)• Cold soil temperature• Excessively wet or dry soils• High or low pH (pH 6-7 ideal)• Fine soil texture (eg. clay)• Restricted rooting

– Compacted, poorly aerated soils – Crops with poor root systems for P uptake

Need for P fertilizer will be higher if P availability is restricted

Phosphorus is Relatively Immobile in the Soil

Has important effect on P management decisions

34

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

35

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

36

Some crops can increase rooting when they contact a fertilizer reaction zone

02468

10

Roo

ts in

R

eact

ion

Zon

e (%

)

FlaxWheat

Rapeseed

Buckwheat

Unfertilized SoilP Reaction Zone

• Canola is very good at increasing rooting in the fertilizer band– Very good at using

fertilizer P

• Also very good at using residual soil P– Excretes organic acids

to mobilize PStrong and Soper

37

Banding P Near the Seed-Row Ensures that Roots Will Contact the P Granule Early in Growth

BroadcastBroadcast BandedBanded

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

38

Phosphorus Should be Banded

• P will not move to roots so roots must contact bands

• Bands must be placed where roots will contact them early in season– Near the seed-row

• Seed-placed• Side-banded

Effect of rate and placement of MAP on stand density and grain yield of canola

• Too much fertilizer close to the seed can damage the seed and reduce yield

• Damage is from the nitrogen in the MAP

0.0

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2.0

0 20 40 80P2O5 Rate (kg/ha)

Gra

in Y

ield

(kg/

ha)

0

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250

plan

ts p

er 6

.1 m

Yield-In RowStand-In Row

Nyborg and Hennig 1969.

40

Canola

• Canola is highly responsive to P on very low P soils– Can use soil P well if soil test P

is moderate to high• Yield will usually be optimized with

15 to 20 lb P2O5 ac-1

• Place as starter near or in the seed-row

• Response to starter more likely on cold soils, with early seeding

No Starter P

35 bu/acre25 bu/acre

25 lb P2O5 applied as MAP

15 lb NW MKP per ac, equiv. to ~ 7 ppm Olsen P

Sulphur Deficiency is Very Common In Canola

• Canola requires more S than cereal and pulse crops.

348124Sulphur removal (kg/ha)

AlfalfaPeasCanolaWheat

42precipitation

Plants Access S from Soil Solution

Soil solutionSO4

-2

As with other nutrients, fertilizer additions make up the difference between crop demand and soil supply

dissolution

Mineralization

Immobilization

Rain,irrigation, atmospheric deposition

Gypsum

Sulphur Deficiency

Sulphur is not mobile, so does not move from old to young tissue

Yellowing of younger leaves is early symptom

Often the S deficiency results in a reddish-violet color, similar to P and N.

Cupping of younger leaves is a symptom of critical S stress,

Sulphur Deficiency Symptoms

• Sulphur deficiencies are usually patchy in a field, since S supply is normally highly variable

Adding N without S Can Depress Canola Yield on an S-deficient soil

0.0

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Can

ola

Yiel

d (t/

ha)

ControlN bandedN broadcast

Grant 1994

Increasing N with S

Increasing N with No S

Adequate S is Needed, But Specific N:S Ratio May Not Be That Important

• High N:S ratio can indicate an S deficiency

• However, once a S deficiency is corrected there is little or no response to adding more S with increasing N rate.

Sulphur Sources

• Ammonium sulphate• Ammonium

thiosulphate• Gypsum • Microessentials S-15

• Elemental S• Bentonite blends

– Tiger 90

• Microessentials S-15

Sulphate Sources Elemental Sources

Manage sulphate and elemental sources differently

Sulphate Sources Are Immediately Available so Timing of Application is Flexible

• Ahead of seeding– Will not volatilize– May immobilize or leach

• Near seeding– Readily available

• Post-seeding– Can be effective, even when delayed

Sulphate Sources Are Mobile in the Soil so Placement Options Are Flexible

• Banding• Broadcast• Dribble-band• Seed-placement

– Avoid excesses that could cause toxicity

Elemental Sources Must Oxidize to Sulphate

• Apply far before crop requirement• Use finely divided product• Broadcast rather than band

– Want to maximize contact with microbes

• Leave on surface to “weather”• Incorporate after weathering• Part of long-term program

Canola yield as affected by placement of applied sulphur

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Yie

ld (

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Broadcast Seedplaced PP Band

Control Tiger 90 Am. Sulph.

Canola yield as affected by residual S applied the previous year

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Yie

ld (

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Broadcast PP Band

Control Tiger 90 Am. Sulph.

Effect of a single year’s application of S sources on canola yield over three years on a sandy loam soil

Treatment Year 1 Year 2 Year 3 TotalControl 18.1 9.3 11.0 38.4Sp. Brd T-90 15.3 14.7 25.0 55.0Sp. Brd AS 34.6 31.4 24.0 90.0Banded T-90 16.0 10.4 12.3 48.7Banded AS 35.7 31.5 28.1 95.3Seedrow T-90 16.6 13.7 18.6 48.9

Conversion of S to Sulphate is not Reliable

• Under Canadian conditions, we cannot rely on elemental sources to provide enough available sulphate on deficient soils during the following crop year– May be beneficial in long-term planning

Summary

• Canola is effective at accessing nutrients from the soil– Also good at using fertilizer nutrients

• Need to consider soil nutrient supply when assessing fertilizer demand– Immediately available nutrients and potential

mineralization• Select proper rate, source, timing and placement

– Match management practices to environment to minimize losses and maximize efficiency

Thank YouFor your Attention