Taking A Closer Look At A Key Management Practice - Dr. Peter Thomison, Extension Specialist, Ohio State University, from the 2018 Conservation Tillage and Technology Conference, March 6 - 7, Ada, OH, USA. More presentations at https://www.youtube.com/channel/UCZBwPfKdlk4SB63zZy16kyA

1. Implications of Planting
Depth Recommendations
CTC 2018
Alex Lindsey, Peter Thomison, and Paul Carter

2. Current Planting Depth Recommendations
• Current recommendation is 1.5-2.0 inches
• Deeper planting recommended under
drier conditions
• Producers planting early may plant
shallower
• Seed will emerge sooner with warmer
temperatures
• Soils that crust after heavy rains

3. Shallow planting depths - Risks
• Increases stress.
• Increases potential for injury from
pre-emergent herbicides.
• Less developed roots.
• Smaller stalk diameters, ears and yields.

5. Planting Depth Affects
Crown Root Development
Source: http://ohioline.osu.edu/agf-fact/0150.html
½ in.
2 in.
>3 in.

6. Planting depth (2.5” on left to 0.5” on right) determines the
placement of nodal roots, which are developing too near
the soil surface in shallow-planted corn plant at right
Source: P. Thomison, Ohio State University, M. Jeschke and S. Butzen, DuPont Pioneer

7. Rootless corn syndrome caused by shallow
planting and dry soils conditions
Source: P. Thomison, Ohio State University, M. Jeschke and S. Butzen, DuPont Pioneer

8. Late Emergers (aka “Runts”)
V5
V7

9. Plant that was
2 leaf stages
behind is
late to silk.
Source: J. Coulter, U. of Minnesota

10. Source: J. Coulter, U. of Minnesota

11. Corn product yield response to planting depth
in 2011 and 2012
Source: P. Thomison, Ohio State University, M. Jeschke and S. Butzen, DuPont Pioneer

12. Planting Depth Effects on Yield, Final
Stand and Runts, 10 Ohio Locations
121
181 182
100
110
120
130
140
150
160
170
180
190
200
0.5 1.5 3.0
19457
32029
30875
15000
20000
25000
30000
35000
0.5 1.5 3.0
31
6
3
0
10
20
30
40
50
0.5 1.5 3.0
Yield (Bu/A) Population (ppa) % Runts
Planting Depth (inches)
Source: OSU, 2012 - 2013

13. Importance of Stand Uniformity and Yield
•“Uniform emergence is critical for achieving high
yields…”
•“Farmers cannot reach top yields if they have some
plants that are 1 or 2 days late….”
•Planting depth is major factor contributing to
uniform emergence.

14. Importance of Stand Uniformity and Yield
•Recent studies suggest variable seeding depth
planting within fields may improve corn yield
especially when soil moisture conditions become
less than ideal.
•Our knowledge of corn response to planting depth
across different soil types and conditions is limited.

15. Importance of Stand Uniformity and Yield
New tools may enable monitoring soil moisture during
planting operation (Precision Planting - SmartFirmer)
• Soil organic matter (optic sensor)
• Seed germination moisture
• Uniform soil moisture consistency
• Clean furrow --- crop residue
• Soil temperature
>>A greater understanding of the influence of soil texture,
soil moisture, and soil temperatures on seeding depth is
needed to assess variable rate depth technology.

16. Research Questions
1. What is the variability
in temperature and soil
moisture at different
planting depths?
2. How does varying
planting depth impact
emergence rates and
grain yield?

17. Site Characteristics – South Charleston, OH
• Field 1: Crosby soil series
• Silt loam soil texture
• 2.7% organic matter
• Field 2: Kokomo soil series
• Loam soil texture
• 4.4% organic matter
• 4 row plots (30-in row spacing)
• 10 x 150 ft
• Three targeted planting depths
• 1 in
• 2 in
• 3 in
• P1197AM
• 35,000 seeds/A
• Planted 16 May
• Field 1: 9 AM
• Field 2: 12 PM

18. Sensor Installation

19. Sensor Installation
• Installed sensors within 1 hour
of planting
• Connected to logger
• Recorded average values every
10 minutes
• Soil temperature
• Soil volumetric water content

20. Daily Measurements
Measured
plant-to-plant
spacing at V3

21. V3 Biomass Collection
Marker shows soil line
Seed to color change called “actual
planting depth”, or “depth to seed”
(did not extend mesocotyl for this
measurement)
• 10 ft section harvested at
overall V3 stage
• Staged each plant
• Biomass
• Depth to seed
• Plant to plant spacing

22. R6 data collection
• 5 ft section harvested by hand at R6
• Bent section (darkest tissue)
considered seed placement
• Measured from bend to soil line
within brace roots
• Considered “depth to seed” or
“actual planting depth” at R6
• Plant to plant spacing
• Per plant grain yield
• Plot Yield

23. Results

24. Field 1: Crosby (lighter soil)
Target Depth (in) Actual Depth Achieved (R6 section)
1 1.2 a
2 1.6 b
3 2.5 c
P-Value <0.001
Target Depth (in) Actual Depth Achieved (V3 section)
1 1.1 a
2 1.6 b
3 2.4 c
P-Value <0.001

25. 0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
40
50
60
70
80
90
100
5/15 5/17 5/19 5/21 5/23 5/25 5/27 5/29 5/31 6/2 6/4
Precipitation(in)
Temperature(F) 1 in 2 in 3 in air precip
5” of rain total
over the
emergence
window
• Soil temperatures tended to be greater than air temperatures.
• Widest variance in temperatures was seen at shallower depths,
with shallow depths being warmer than deeper depths.
• Precipitation events seemed to lessen the differences between
soil depths

26. 0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
40
50
60
70
80
90
100
5/15 5/17 5/19 5/21 5/23 5/25 5/27 5/29 5/31 6/2 6/4
Precipitation(in)
Temperature(F)
1 in 2 in 3 in air precip
Depth
(in)
Avg Daily
Temp (F)
Avg. Temp. Range
(max-min) (F)
1 68.9a 17.8a
2 68.5b 15.3b
3 68.0c 11.7c
P-Value <0.001 <0.001
5” of rain total
over the
emergence
window

27. 0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
5/15 5/17 5/19 5/21 5/23 5/25 5/27 5/29 5/31 6/2 6/4
Precipitation(in)
0%
5%
10%
15%
20%
25%
30%
35%
40%
5/15 5/17 5/19 5/21 5/23 5/25 5/27 5/29 5/31 6/2 6/4
VolumetricWaterContent 1 in 2 in 3 in
FC = 38%
PWP = 14%
Depth
(in)
Avg Daily
VWC (%)
Avg. VWC Range
(max-min) (%)
1 28.7 3.0a
2 28.4 1.2b
3 29.2 1.1b
P-Value 0.647 0.002
1 < 2 and 3
P < 0.05
1 > 2 and 3
P < 0.05
1 = 2 = 3
P > 0.07

28. 0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
16 18 20 22 24 26 28 30 32
CumulativeEmergence(%)
Emergence Date (May)
V3 Emergence Curves
1" 2" 3"
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
16 18 20 22 24 26 28 30
CumulativeEmergence(%)
Emergence Date (May)
R6 Emergence curves
1" 2" 3"
Depth
(in)
T10 to T90
1 4.0 d
2 3.5 d
3 2.5 d
Depth
(in)
T10 to T90
1 4.5 d
2 4.0 d
3 2.5 d

29. Depth (in) Date Emerged V3 Biomass (g)
1 22.1b 0.89b
2 21.8a 0.98a
3 22.4b 1.01a
P-Value 0.029 0.030
Depth (in) Date
Emerged
Yield Per
Plant (R6)
Plot Yield
(bu/A)
1 22.5a 147.3 256.1
2 22.7a 149.1 249.9
3 23.3b 150.9 249.9
P-Value 0.028 0.910 0.354
y = 0.1083x + 0.7799
R² = 0.0393
P = 0.003
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
PerPlantBiomass(dried,g)
Seed Depth (inches)
Biomass vs depth to seed (V3 only)
y = 12.51x + 127.22
R² = 0.0341
P = 0.042
0
50
100
150
200
250
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
PerPlantYield(dried,g)
Seed Depth (inches)
Yield vs depth to seed (R6 only)

30. y = -9.8715x + 371.01
R² = 0.159
P = 0.007
y = -8.2023x + 337.45
R² = 0.1041
P = 0.040
y = -4.0495x + 246.99
R² = 0.0142
P = 0.452
0
50
100
150
200
250
20 21 22 23 24 25 26 27 28
PerPlantYield(dried,g)
Emergence Date (May)
Yield vs emergence date (R6 only)
1" 2" 3"
y = -0.0896x + 2.8812
R² = 0.2493
P < 0.001
y = -0.0895x + 2.9387
R² = 0.1669
P < 0.001
y = -0.0757x + 2.7009
R² = 0.0635
P = 0.018
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
20 21 22 23 24 25 26 27 28 29 30 31 32
PerPlantBiomass(dried,g)
Emergence Date (May)
V3 Biomass vs emergence date (V3 only)
1" 2" 3"
As emergence date increased, biomass and per plant grain yield decreased
regardless of planting depth

31. Kokomo (darker soil)
Target
Depth
(in)
Actual Depth
Achieved (R6 section)
1 1.8 a
2 2.8 b
3 3.0 b
P-Value <0.001
Target
Depth
(in)
Actual Depth
Achieved (V3
section)
1 1.1 a
2 1.8 b
3 2.1 c
P-Value <0.001
Depth
(in)
Avg Daily
Temp (F)
Avg. Temp.
Range (F)
1 69.4 18.9a
2 69.3 15.8b
3 68.5 12.1c
P-Value 0. 259 <0.001
Depth
(in)
Avg Daily
VWC (%)
Avg. VWC
Range (%)
1 29.9 3.9a
2 35.0 1.0b
3 34.6 0.5b
P-Value 0.198 0.010
• 1 in less than other depths
more often than Crosby field
• 2 and 3 in very similar in
moisture

32. 0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
20 22 24 26 28 30
CumulativeEmergence(%)
Emergence Date (May)
V3 Emergence Curves
1" 2" 3"
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
20 22 24 26 28 30
CumulativeEmergence
Date of May
R6 Emergence Curves
1" 2" 3"
Depth T10 to T90
1 4.0 d
2 4.0 d
3 4.5 d
Depth T10 to T90
1 4.0 d
2 4.0 d
3 5.5 d
• Longer emergence window with increasing depth than in Crosby field
• Longer to reach T50 than in Crosby field
• Similar results for biomass and yield per plant vs emergence date as Crosby field

33. Depth (in) Date Emerged V3 Biomass (g)
1 25.2 0.70
2 25.2 0.70
3 25.3 0.98
P-Value 0.902 0.789
Depth (in) Date
Emerged
Yield Per
Plant (R6)
Plot Yield
(bu/A)
1 24.8 152.3 236.6
2 25.0 146.7 232.2
3 25.2 153.3 225.7
P-Value 0.444 0.645 0.567
y = -0.0145x + 0.7435
R² = 0.0008
P = 0.990
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
PerPlantBiomass(dried,g)
Seed Depth (inches)
Biomass vs depth to seed (V3 only) y = 6.8753x + 133.6
R² = 0.0149
P = 0.173
0
50
100
150
200
250
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
PerPlantYield(dried,g)
Depth to Seed (inches)
Yield vs depth to seed (R6 only)

34. Conclusions
• Lighter soil (Crosby) exhibited fastest emergence at 3-in.
• 3-in. slowest emergence in darker soil (Kokomo).
• Delays in emergence date decreased biomass and grain yield.
• Correlation existed between grain yield and actual planting
depth.
• Project will be repeated in 2018.

35. Tips for promoting uniform emergence
• Select appropriate planting depths BUT avoid shallow plantings.
• Consider row cleaning attachments – uneven residue, cloddy
surface.
• Adopt strip tillage – surface residue.
• Avoid excessive tillage prior to planting – surface crusting.
• Avoid excessive downward pressure – compaction on top of
furrow.
• Avoid planting when “sticky”- smearing sidewalls with double-disk
openers.

36. Acknowledgements
The authors would like to
acknowledge DuPont
Pioneer for their seed
donation and funding
support through the Crop
Management Research
Award program.

37. THANK YOU
Questions?

38. Peter Thomison
Extension Specialist
Corn Cropping Systems
The Ohio State University