Drought Stress and Ontario Soybean Yields€¦ · 17.02.2017 · Hugh Earl, U of G Horst Bohner, OMAFRA. 160.6 bu/ac Kip Cullers 171.8 bu/ac Randy Dowdy 106.3 bu/ac Robert and Jason

Drought Stress and

Ontario Soybean

Yields: Unravelling the

Mystery

Hugh Earl, U of G

Horst Bohner, OMAFRA

160.6 bu/ac

Kip Cullers

171.8 bu/ac

Randy Dowdy

106.3 bu/ac

Robert and

Jason Lakey

Illinois

http://www.bing.com/images/search?q=new+world+record+soybean+holder&view=detailv2&qpvt=new+world+record+soybean+holder&id=77C229B49820616AD2B623D0F26DACFE1AA0F45B&selectedIndex=2&ccid=zv41NCyE&simid=607999054904758223&thid=OIP.Mcefe35342c84622dafa324296d2b0ad7o0


214.7 Bushel Yields: Coming Soon to a

Field Near You?

…soybeans can potentially produce hundreds

of pods per plant. If every node on every

branch produced multiple racemes and every

raceme produced multiple flowers, a soybean

plant can have a thousand potential pod sites.

Rain makes grain!

Where do High Yields Come From?

Basic principles of yield determination are more or less

universal across grain crops.

Agronomic decisions should be made with a clear

understanding of how yield is determined from a crop

physiology standpoint.

There are many persistent misconceptions about how

crops “work”.

Why Does Yield Vary So Much?

True Causes of Large Yield Variations are Often

Unknown

The “most limiting factor” idea is not a

very complete model of crop yield

limitations!

Factors may be co-limiting

(interacting).

The current most limiting factor will

change over the season, and even

over a single day.

Crop yield determination is much more

complicated than can be described

with this model.

Water Stress in Ontario Soybean:

Are we losing yield to water stress? If so, how much?

Uncertainties

How much of the in-season rainfall do we get to use?

To what extent can soil water depletion delay the onset

of stress during dry periods?

Does dry soil at any point in the root profile constitute a

water stress?

Quantifying Yield Lost to Drought Stress

1. Quantify yield reductions due to water stress

under naturally-occurring (rainfed) conditions

Compare to yield under water-replete (irrigated)

conditions

2. Identify the specific aspects of crop growth

and yield formation impacted by water stress

Interception of solar radiation, biomass

production, pods per unit area, seeds per pod,

seed size

Past Studies:

•Yield more sensitive to stress during pod elongation and

seed fill. Less sensitive to early season stress.Shaw and Lang, 1966; Doss et al., 1974; Andriani et al., 1991; Foroud et al., 1993

• Pods per unit area most sensitive yield component, but

late-season stresses can also reduce seed size.Sionit and Kramer, 1977; Korte et al.,1983; Brevedan and Egli, 2003

• Late-season stress leads to early canopy senescence,

shortening the seed fill period.Korte et al., 1983; Specht et al., 1986; Foroud et al., 1993

Methods:

S

S

S

25 m

25 m

25 m

12.5 mDry

Dry

Dry

Dry

Wet

Wet

Wet

Wet

~33 m

S

Solid set sprinkler, 180

Final seed yield and yield

components

Buffered in-season dry

matter harvests

2009

Solid set irrigation

4 replications

Methods:

2010 onward

Hose-pull boom cart

4 replications

B B406 412B B

405 411B B

404 410B B

403 409B B

402 408B B

401 407B BB BB BB BB BB BB BB BB BB B

306 312B B

305 311B B

304 310B B

303 309B B

302 308B B

301 307B B

206 212B B

205 211B B

204 210B B

203 209B B

202 208B B

201 207B BB BB BB BB BB BB BB BB BB B

106 112B B

105 111B B

104 110B B

103 109B B

102 108B B

101 107B B

10 b

uff

er

plo

ts10 b

uff

er

plo

ts

Year 1 (2009)

-5

0

5

10

15

20

0

50

100

150

200

250

300

350

400

450

500

0 25 50 75 100 125 Weekly

tem

pera

ture

devia

tio

n f

rom

10

-yr

avera

ge (

°C)

Pre

cip

itati

on

(m

m)

Days after planting

Cumulative precipitation + irrigation

Cumulative precipitation

10-year average cumulative precipitation

Year 1 (2009)

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 25 50 75 100 125

Ca

no

py in

terc

ep

tan

ce

of s

ola

r ra

dia

tio

n

Days after planting

Irrigated

Rainfed

0

100

200

300

400

500

600

700

800

900

0 25 50 75 100 125

Ab

ove-g

rou

nd

dry

matt

er

(g m

-2)

Days after planting

Irrigated

Rainfed

yield yield pods m-2 seeds pod-1 100-seed wt

bu acre-1 kg ha-1 g

Irrigated 55.2 3700 898 2.38 17.3

Rainfed 50.2 3369 853 2.40 16.5

P-value 0.03 0.03 0.28 0.92 0.15

Irrigated / Rainfed 1.098 1.098 = 1.052 x 0.995 x 1.047

Year 2 (2010)

-5

0

5

10

15

20

0

50

100

150

200

250

300

350

400

450

500

0 25 50 75 100 125

Weekly

tem

pera

ture

devia

tio

n f

rom

10-y

r avera

ge (

°C)

Pre

cip

itati

on

(m

m)

Days after planting




Year 2 (2010)

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 25 50 75 100 125

Ca

no

py in

terc

ep

tan

ce

of

so

lar

rad

iati

on

Days after planting

Irrigated

Rainfed

P < 0.01

0

100

200

300

400

500

600

700

800

900

0 25 50 75 100 125

Ab

ov

e-g

rou

nd

dry

ma

tte

r (g

m-2

)

Days after planting

Irrigated

Rainfed

P < 0.001


bu acre-1 kg ha-1 g

Irrigated 58.1 3899 1005 2.39 16.3

Rainfed 53.7 3598 933 2.52 15.3

P-value 0.007 0.007 0.28 0.44 0.07


Year 3 (2011)

-5

0

5

10

15

20

0

50

100

150

200

250

300

350

400

450

500

0 25 50 75 100 125

Weekly

tem

pera

ture

devia

tio

n f

rom

10-y

r avera

ge (

°C)

Pre

cip

itati

on

(m

m)

Days after planting




Year 3 (2011)

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 25 50 75 100 125

Ca

no

py in

terc

ep

tan

ce

of

so

lar

rad

iati

on

Days after planting

Irrigated

Rainfed

P < 0.05

P < 0.05

P < 0.05

0

100

200

300

400

500

600

700

800

900

0 25 50 75 100 125

Ab

ov

e-g

rou

nd

dry

ma

tte

r (g

m-2

)

Days after planting

Irrigated

Rainfed

P < 0.05

P < 0.05

P < 0.05P < 0.05


bu acre-1 kg ha-1 g

Irrigated 56.2 3768 923 2.51 14.0

Rainfed 45.5 3051 790 2.40 13.8

P-value 0.04 0.04 0.005 0.16 0.60


Canopy Senescence

Canopy Senescence

NDRE

Year 2009 2010 2011

Date Sep 8 Sep 1 Sep 12

DAP 113 97 101

Irrigated 0.272 0.218 0.219

Rainfed 0.214 0.166 0.154

P-value <0.01 <0.01 <0.05

Irrigated Rainfed

Rep 1

Rep 2

Rep 3

Rep 4

2009

Year 4 (2012)

-5

0

5

10

15

20

0

50

100

150

200

250

300

350

400

450

500

0 25 50 75 100 125

We

ek

ly T

em

pe

ratu

re A

no

maly

(°C

)

Cu

mu

lati

ve

Pre

cip

ita

tio

n (

mm

)

Days after Planting

Year 5 (2013)

-5

0

5

10

15

20

0

50

100

150

200

250

300

350

400

450

500

550

0 25 50 75 100 125

We

ek

ly T

em

pe

ratu

re A

no

maly

(°C

)

Cu

mu

lati

ve

Pre

cip

ita

tio

n (

mm

)

Days after Planting

Years 4 and 5 (2012 - 2013)

yield yield pods m-2

seeds pod-1

100-seed wt

bu acre-1

kg ha-1

g

2012

Irrigated 70.2 4714 1283 2.32 16.3

Rainfed 60.6 4064 1049 2.28 17.4

P-value <0.0001 <0.0001 <0.0001 0.92 0.15


2013

Irrigated 64.7 4343 1009 2.32 17.6

Rainfed 62.6 4200 1001 2.29 17.3

P-value 0.014 0.014 0.65 0.44 0.07


Mean responses across 15 varieties.

2009 – 2013 Summary

1. There was significant yield loss attributable

to water stress in all five years.

•Yield loss ranged from 3% to 24%.

•These estimates are probably conservative.

• Yield loss occurred even when the in-season

rainfall total exceeded the 10-yr average (2010,

2013), or when it equaled the 10-yr average

and was very well distributed (2009)

2. When yield losses were small, it was

sometimes difficult to parse the yield loss

amongst the various yield components.

• pods m-2 was the component most consistently

affected

3. Early canopy senescence was a consistent

feature of water stress

4. There were never any obvious visual

symptoms of stress, such as leaf wilting.

2009 – 2013 Summary

Water is not everything!

Year Rainfed Yield

Mg / ha

Irrigated Yield

Mg / ha

Increase from

irrigation

2009 3.37 3.70 9.8%

2010 3.60 3.90 8.3%

2011 3.05 3.77 23.6%

2012 4.06 4.71 16.0%

2013 4.20 4.34 3.3%

Average 12.2%

24.9%

Highest yields on this farm: 5.4 Mg / ha

Highest yields in Ontario: 6.7 Mg / ha

When during the season is yield determined?

The Critical Developmental Stage is the one where the

most Variable Yield Component is Determined.

For soybean:

Yield = pods per m2

x seeds per pod

x mass per seed

What determines pod number?

Pod number (and therefore seed number) is

determined by the plant growth rate during the

critical period (R2 to R5).

Pod number is NOT a direct function of plant size.

It’s now how big the crop is – what matters is how

fast it is growing.

Maximizing pod numbers is mostly a matter of

maximizing crop growth rate during the critical

period.

(Data of Vega, 2001)

Think at the Crop Scale

The Plant Community (“Crop Canopy”) is more

Relevant than Individual Plants. Think on a Ground

Area Basis.

We measure yield per unit area, not on a single plant

basis. Plant size is (almost) irrelevant.

Many important processes that determine yield can

only be properly understood at the crop canopy (plant

community) scale.

For maize and a few other crops, individual plant size

can be important. For soybean it is very unimportant.

Plant size is unimportant in soybean

• Maize is prone to barrenness when there is insufficient assimilate flux

prior to anthesis (i.e., plants are too small).

• Species with a larger number of fruiting structures, including soybean

are much less sensitive to plant size.

(Vega and Sadras, 2003)

Soybean is insensitive to seeding rate

0

20

40

60

80

100

120

0 100 200 300 400 500

Seeding rate (thousands per acre)

Yie

ld (

pe

rce

nt

of

ma

xim

um

)

2005, early

2005, late

2006, early

2006, late

k = 0.0191

Response of soybean yield to seeding rate.

Radiation Capture

The Crop Growth Rate is Primarily Determined by

Radiation Capture

X X RUE =Biomass

Radiation Capture

time

Radiation Capture

The crop growth rate during the critical period (R2 - R5) determines final

pod numbers Maximizing the crop growth rate requires complete

interception of sunlight.

Row Width still Matters

Bu/ac1) 30” no-till (130 000) 65.3

2) 30” managed (130 000) 69.8

3) 30” managed (170 000) 69.4

4) 15” no-till (170 000) 69.5

5) 15” managed (170 000) 69.9

Managed = 180 lbs/ac MESZ and 6-24-24 (2X2), 3 gallons

6-24-6 IF, spring strip tillage, foliar fungicide and feeding.

Elora 2016, P = 10 ppm, K = 96 ppm

Closing the Yield Gap

Bu/ac1) 30” no-till (130 000) 62.0

2) 30” managed (130 000) 63.5

3) 30” managed (170 000) 64.9

4) 15” no-till (170 000) 65.4

5) 15” managed (170 000) 67.0



Lucan 2016, P = 14 ppm, K = 109 ppm

Closing the Yield Gap

Wide rows are not a good choice

if rows do not fill by R3

y = 0.4732x - 6.7867

Variety Selection is Key

y = 1.125x - 86.232

Bu/ac

1) 15” no-till (Variety A) 69.5

2) 30” managed (Variety A) 69.8

3) 15” no-till (Variety B) 75.7

4) 30” managed (Variety B) 74.7

5) 15” no-till (Variety C) 81.8

6) 30” managed (Variety C) 81.5

Good Variety Choice Equals Profit



Elora 2016, P = 10 ppm, K = 96 ppm

171.8 bu/ac

Randy Dowdy

Good Soil Fertility is Essential



Bu/ac

1) Check 64

2) MESZ (375 lbs/ac) 72

3) MESZ (375 lbs/ac + 70

333 lbs/ac potash)

Mega Fertilizer

Bornholm 2016, P = 17, K = 98

Bu/ac

1) Check 64

2) MESZ (375 lbs/ac) 72

3) MESZ (375 lbs/ac + 70

333 lbs/ac potash)

4) Trt. 2+3+ N (150 lbs/ac) 70

Mega Fertilizer

Bornholm 2016, P = 17, K = 98

Yiel

d (

bu

/ac)

CORN

SOY

WHEAT

Yield Trends in Ontario of Corn, Soybean, Winter Wheat1981-2015

Yiel

d (

bu

/ac)

CORN

SOY

WHEAT

Yield Trends in Ontario of Corn, Soybean, Winter Wheat1981-2015

35 lbs P2O5, 25 K2O

30 lbs P2O5, 18 K2O

28 lbs P2O5, 46 K2O

80% yield increase

63 lbs P2O5, 45 K2O

65% yield increase

50 lbs P2O5, 30 K2O

35% yield increase

37 lbs P2O5, 61 K2O

Hooker, UG2013

No P appliedSoil test P = 7 ppm

P broadcast applied

Soybean response to P and K fertilizer

Starter (per ac)Approx. background soil test P and K (ppm)

ANOVA across background Low P

Low KLow PHigh K

High PHigh K

bu/ac

No Fertilizer 56 b

6-24-6 @ 3 gal (IF) 58 ab

MAP @ 100 lbs (2x2) 59 a

0-0-60 @ 80 lbs (2x2) 58 ab

6-28-28 @ 90 lbs (2x2) 59 a

6-28-28 @ 180 lbs (2x2) 60 a

Soybean yield response to background fertility and starter fertilizerLucan (2014-2016)

n=12Mean separation within column statistically significant at P=0.05 @cropdoc2 #SWAC17

NOTABLE NOTE:180 lbs 6-28-28 = 50 lbs of P2O5 or K2O Current rec = 20 lbs/ac P2O5, 30 lbs/ac K2O



Low KLow PHigh K

High PHigh K

bu/ac

No Fertilizer 56 b 56 de

6-24-6 @ 3 gal (IF) 58 ab 58 cd

MAP @ 100 lbs (2x2) 59 a 62 ab

0-0-60 @ 80 lbs (2x2) 58 ab 55 e

6-28-28 @ 90 lbs (2x2) 59 a 59 bc

6-28-28 @ 180 lbs (2x2) 60 a 62 a


n=12Mean separation within column statistically significant at P=0.05 @cropdoc2 #SWAC17



Low KLow PHigh K

High PHigh K

bu/ac

No Fertilizer 56 b 56 de 63 a <0.05

6-24-6 @ 3 gal (IF) 58 ab 58 cd 64 a <0.05

MAP @ 100 lbs (2x2) 59 a 62 ab 64 a <0.05

0-0-60 @ 80 lbs (2x2) 58 ab 55 e 64 a <0.05

6-28-28 @ 90 lbs (2x2) 59 a 59 bc 64 a <0.05

6-28-28 @ 180 lbs (2x2) 60 a 62 a 63 a ns


n=12, P = 10, K = 129 (low) and P = 27, K = 166 (high)Mean separation within column statistically significant at P=0.05 @cropdoc2 #SWAC17

Starter (per ac)Background treatment

Low PLow K

High PLow K

Low PHigh K

High PHigh K

bu/ac

No starter 53c 55b 55c 60a

6-24-6 in-furrow 55b 56b 56b 61a

MAP @ 100 lbs (2x2) 55b 56b 58a 61a

0-0-60 @ 80 lbs (2x2) 54b 58a 54c 60a

6-28-28 @ 90-180 lbs (2x2) 57a 59a 58a 61a

Soybean yield response to background fertility and starter fertilizerAverage across 17 site-years

Mean separation within column statistically significant at P=0.05@cropdoc2 #SWAC17

Fertility Summary

• Fertility is KEY to high yields!!!

– Soil health includes good fertility

– But it’s not as simple as applying high rates

of fertilizer

• Building soil test values to a reasonable level

provides more consistent and higher yields

• Low soil tests reduces yield by 4 – 7 bu/ac

214.7 Bushel Yields: Coming Soon to a

Field Near You?… one important step was spoon feeding N, P and K through

the drip irrigation based on growth stage. They applied 610

lbs. of nitrogen, 40 lbs. of phosphate and 200 lbs. of potash,

and adequate micronutrients were added at planting.

2016 SMaRT Trial Locations

KTS Starter Fertilizer

Broadcast Gypsum

Planting Rate

ILeVO

Field Rolling

Prescription Foliar Fertilizer

White Mold Fungicide Comparison

Intensive Management

Radiate

Blackmax 22

2016 Prescription foliar fertilizer trial locations

Field-specific prescription foliar fertilizer mixtures were

compared to an unfertilized control at nine locations in 2016.

Composite soil samples were collected from the trial area in

the spring of 2016 and sent to Midwest Labs for testing.

The field-specific prescription foliar fertilizer mixtures were

developed by AgroLiquid and based on soil test nutrient

levels.

AgroLiquid also determined the application timing: V4 for row

spacing of 15” or less and R1 where row spacing was greater

that 15”.

Prescription foliar fertilizer trial

Location O.M. P K Mg Ca pH CEC S Zn Mn

% ------------ ppm ------------ 1:1meq/ 100g ------- ppm ------

Cass 1.4 93 172 93 1057 6.7 6.5 8 2.1 4Ionia 2.1 50 152 241 1243 6.6 9.3 8 1.9 7Gratiot 2.8 27 165 248 1593 7 10.6 17 2.4 4St. Joseph 1 64 99 79 665 6 5.1 23 1.8 7Van Buren 1.5 29 162 81 719 5.9 5.7 13 1.4 16Lenawee 2 2.1 99 177 179 975 6.1 8 10 1.7 3 Monroe 2.4 49 177 193 1131 6 9.2 13 2.5 4Lenawee 1 2.7 16 141 254 1712 6.2 12.6 15 1.4 5Sanilac 3.7 31 244 227 2460 7.9 14.9 20 1.8 2

Soil test levels at the 2016 prescription foliar fertilizer trial locations

Bold figures indicate low or very low soil test levels.

Location Foliar fertilizer products and application ratesFertilizer

cost$/ac

Cass 1.5 gal/ac of fertiRain, and 1 qt/acre of Manganese $19.10 Ionia 1.5 gal/ac of fertiRain, 2 qt/acre of Manganese, and 2 qt/ac of LiberateCa $28.70 Gratiot 1.5 gal/ac of fertiRain, and 1 qt/acre of Manganese $19.10 St. Joseph 1.5 gal/ac of fertiRain, and 1 qt/acre of Manganese $19.10 Van Buren 1.5 gal/ac of fertiRain, 1 qt/acre of Manganese, and 1 qt/ac of LiberateCa $19.50 Lenawee 2 1.5 gal/ac of fertiRain, 2 qt/acre of Manganese, and 2 qt/ac of LiberateCa $28.70 Monroe 1.5 gal/ac of fertiRain, 2 qt/acre of Manganese, and 1 qt/ac of LiberateCa $20.80 Lenawee 1 1 gal/ac of fertiRain, 1 gal/ac of Sure-K, and 2 qt/acre of Manganese $21.40 Sanilac 1.5 gal/ac of fertiRain, and 1 qt/acre of Manganese $19.10

Prescription foliar fertilizer products, application rates and costs for

each location

Analyses of the foliar fertilizer products are listed below:fertiRain: 12-3-3 plus 1.5% S, 0.10% Fe, 0.05% Mn, and 0.10% Zn LiberateCa: 3% calcium from calcium sulfate Manganese: 4% manganese from manganese sulfateSure-K: 2-1-6

*1.5 *1.4

1.20.8 0.5

0.1

-0.1-0.5

-1.5

0.3

-3

-2

-1

0

1

2

3

4

Yie

ld d

iffe

rence

(bu/a

c)

Lowest breakeven yield increase for all sites (2.1 bu/ac)

* The yield difference was statistically significant at these locations

Yield difference produced by a single application of a

prescription foliar fertilizer in 2016

The prescription foliar fertilizer treatment increased soybean yields at two of nine locations in 2016.

However, the yield increases were not large enough to cover the cost of the foliar fertilizer ($19.10 to $28.70 per acre).

The lack of a profitable response to foliar fertilization is most likely due to the medium to high soil test levels for many of the nutrients in the trials.

However, soil test levels for sulfur were low at 3 sites and manganese was very low to low at 8 sites.

Prescription foliar fertilizer trial

Production Practices That Often Have

A Large (5+ Bu/A) Impact on Yield

• Planting Date

• Fertility

• Variety Selection and Placement

• Drainage and Compaction Management

• Insect, Disease, and Weed Management

Production Practices That Often Have

A Moderate (2 to 5 Bu/A) Impact on

Yield

• Foliar Fungicides

• Seed Treatments

• Residue Managment

• Crop Rotation

– Larger first year effect

• Row Spacing

Production Practices That Often

Have A Small (<2 Bu/A) Impact on

Yield

• Seeding Rate and Equipment

• Inoculants

• Micronutrients

– Can be large under the right circumstances

– More important as yield level increases

Thank you.

Any QUESTIONS?

Horst Bohner [email protected]

mailto:[email protected]

Documents

Drought Stress and Ontario Soybean Yields€¦ · 17.02.2017 · Hugh Earl, U of G Horst Bohner, OMAFRA. 160.6 bu/ac Kip Cullers 171.8 bu/ac Randy Dowdy 106.3 bu/ac Robert and Jason