1. Soybean

2. Soybean Growth Stages Vegetative Stages Reproductive Stages
VE – emergence
R1 – beginning bloom
VC – cotyledon (unrolled unifoliolate leaves)
R2 – full bloom
V1 – first trifoliolate*
R3 – beginning pod
V2 – second trifoliolate
R4 – full pod
V3 – third trifoliolate
R5 – beginning seed
V(n) – nth trifoliolate
R6 – full seed
R7 – beginning maturity
R8 – full maturity
* A fully developed trifoliolate leaf node has unrolled leaflets.
When staging a soybean field , each specific V or R stage is defined only when 50% or more of the plants in the field are in or beyond that stage.

3. Young Soybean Plant (Seedling)

4. Development and timing of vegetative growth, flowering, pod development, and seed filling.
(node and leaf
development)
R Stage
Days of R Stages

5. VE
VE (Emergence) = Cotyledons above the soil surface. V1 VC VE
Soybean seed begins germination by absorbing ~50% of its weight in water.
Although soybean can germinate at minimum temperature of 50°F (or less), field emergence is more rapid (~7 days) and uniform if soil temperature is above 65°F.

6. V2 2 1 V2 = Two fully developed trifoliolate leaf nodes
Lateral roots are growing rapidly into the top 6 inches of soil.
Rhizobia bacteria have infected roots and nodules become visible shortly after VE.
N-fixation begins at V2 to V3 stages.

7. (including a sliced nodule)
Root Nodules
(including a sliced nodule)
Nodules
Active nodules have an internal pink color
Root showing nodules

8. Flowers are purple or white (variety)
R1 – Beginning Bloom
R1 = One open flower at any node on the main stem.
Indeterminate varieties:
At R1, plants are in the V7 to V10 stage. Flowering begins on the third to sixth node (depending on V stage at flowering) and progresses upward and downward.
Vegetative growth continues after flowering begins. At R1, less than half of the nodes on the main stem have developed and plants have achieved less than half their final height.
Flowers are purple or white (variety)
Open Flower

9. Flowers are purple or white (variety)
R1 – Beginning Bloom
R1 = One open flower at any node on the main stem.
Determinate varieties:
Vegetative growth is complete before flowering begins. Most or all of the nodes on the main stem have developed and plants grow very little in height after R1.
Flowering occurs at the same time in the top and bottom of the plant. R1 and R2 may occur simultaneously.
Flowers are purple or white (variety)
Open Flower

10. R2 – Full Bloom
R2 = Open flower at one of the two uppermost nodes on the main stem with a fully developed trifoliolate leaf node.
The rapid
dry weight accumulation initially starts in the vegetative plant parts but then gradually shifts to the pods and seeds between R3 and R6.
50% defoliation at R2 reduces yield about 6 percent.
R2 marks the beginning of a period of rapid and constant (linear) dry weight accumulation by the whole plant which continues until shortly after the R6 stage.

11. Growth and Development of a Crop Commodity
Total Biomass
DRY
WEIGHT
g/m2
Vegetative Biomass
Seed Fill
Vegetative Stage
Flowering
and
Seed
Set
Seed Biomass
Physiological
Maturity
Harvest Maturity
TIME
Source: Dennis Egli

12. R4 – Full Pod
R4 = Pod is 2 cm (¾ inches) long at one of the four uppermost nodes on the main stem with a fully developed trifoliolate leaf node.
R4 is start of the most critical period for yield determination.
Yield reductions at R4 result mainly from fewer pods per plant.
Stress can cause pods to abort.
From R4 through R6, stress (moisture, light, nutrients, frost, lodging, defoliation) reduces yield more than any other period.
¾ inch
long pod
Period of rapid dry weight accumulation by the pods (R4 to middle of R5).

13. R4 – Full Pod
R4 is start of the most critical period for yield determination.
From R4 through R6, stress (moisture, light, nutrients, frost, lodging, defoliation) reduces yield more than any other period.
Yield reductions at R4 result mainly from fewer pods per plant.
Stress can cause pods to abort.
Period of rapid dry weight accumulation by the pods (R4 to middle of R5).

14. R6 – Full Seed
R6 = Pod containing a green seed that fills the pod cavity at one of the four uppermost nodes on the main stem with a fully developed trifoliolate leaf node.
“green bean” stage
Stress reduces seed size (weight)
Dry weight accumulation still rapid in seeds, but begins to slow shortly after R6.

15. Sequence of Seed Development (R5 R6)
R5 = Seed is 3 mm (1/8) long
R6 = Green seed fills pod cavity

16. Soybean Pods and Seeds (R6 R8)

17. Components of Soybean Yield
Soybean yield is determined by 3 major components.
Number of pods per plant.
Number of seeds per pod.
Weight per seed (seed size).

18. Soybean: High Yields

19. Keys to High Yields Good genetics Maximize days suitable for growing
Corn: High Yields
4/20/2017
Keys to High Yields
Good genetics
Maximize days suitable for growing
90 to 95% light interception at flowering (R1) through beginning seed (R5)
Adequate nutrients
Adequate, timely water and air
University of Kentucky Grain Crops Extension

20. HABITS Select fields to plant to soybean Rotate crops
Corn: High Yields
4/20/2017
HABITS
Select fields to plant to soybean
Rotate crops
Tillage (minimal): deep ripping, if necessary; no-till where possible
Select high-yielding varieties
Fertilize to soil test and inoculation (if needed)
Timely planting (full season)
Narrow rows (15 inches or less)
Lower seeding rates (100,000 final stand)
Effective, timely pest control
Monitor stands
University of Kentucky Grain Crops Extension

21. Soybean: Crop Rotation
Continuous soybean: about 5 to 10% lower yields than soybean following corn

22. Variety Selection
Are you buying for yield?

23. Based on Yields from 2006 Trials and expected performance in 2007.
More
2007
2006
Favorable
Potent.
Price
Potential
Rank of Variety
UKSPT2
Variety2
Diff.
Acres
Addnl.
per
Revenue
Planted1 MG
Bu./A
Bu.
Bu.4
Lost
1. Pioneer 94M80 L4
56.6
60.5
3.9
92,000
358,800
$9.00
$3,229,200
2. NK S49-Q9
60.2
0.3
75,900
22,770
$204,930
3. Asgrow AG4703
58.8
1.7
56,350
95,795
$862,155
4. Pioneer 94B73
58.5
2.0
47,150
94,300
$848,700
5. Pioneer 94M30 E4
58.4
2.1
44,850
94,185
$847,665
6. Southern Cross Michael
57.6
2.9
40,250
116,725
$1,050,525
7. Asgrow AG4903
59.0
1.5
34,500
51,750
$465,750
8. Asgrow AG3906 3
59.5
0.0
33,350 $0
8. Vigoro V48N7RS
NIT3 ?
9. Pioneer 94M50
60.3
0.2
32,200
6,440
$57,960
10. NK S43-B1
57.9
2.6
27,600
71,760
$645,840
45%
517,500
912,525
$8,212,725
100%
1,150,000
1 Data from the 2007 Kentucky Agricultural Statistics Service (Data provided every 3 years)
2 Data from the 2006 University of Kentucky Soybean Performance Tests Recommended Table (Data provided anually)
3 Not in the 2006 test
4 Data from the 2007 Kentucky Agicultural Statistics Service (Data provided annually)
5 Data from the 2007 University of Kentucky Soybean Performance Tests Recommended Table
The left column top ten varieties based on purchase data. It compares the yield of these top ten varieties in the 2006 Kentucky Soybean Performance Trial (KSPT) to the top-yielding varieties in the same trial. It projects what the expected yield potential lost in 2007 was by purchasing varieties that did not perform as well as others.
Based on Yields from 2006 Trials and expected performance in 2007.
(The 2006 Soybean Performance Trial was predicting yields for 2007)

24. (Based on performance in 2007.)
More
2007
Favorable
Proj.
Price
Projected
Rank of Variety
UKSPT
Variety
Diff.
Acres
Addnl.
per
Revenue
Planted1 MG
Bu./A5
Bu./A
Bu.
Bu.4
Lost
1. Pioneer 94M80 L4
34.4
42.2
7.8
92,000
717,600
$9.00
$6,458,400
2. NK S49-Q9
33.9
8.3
75,900
629,970
$5,669,730
3. Asgrow AG4703
40.5
1.7
56,350
95,795
$862,155
4. Pioneer 94B73
44.4
47,150 $0
5. Pioneer 94M30 E4
43.2
44,850
6. Southern Cross Michael
39.3
40.4
1.1
40,250
44,275
$398,475
7. Asgrow AG4903
39.5
2.7
34,500
93,150
$838,350
8. Asgrow AG3906 3
39.7
33,350
8. Vigoro V48N7RS
40.6
1.6
53,360
$480,240
9. Pioneer 94M50
43.8
32,200
10. NK S43-B1
N.I.T. ?
27,600
517,500
1,634,150
$14,707,350
Does the KSPT accurately predict high-yielding varieties… especially when we have different weather patterns from year to year? Slide 23 attempts to answer that question. This slide looks at how those same Top Ten selling varieties performed in the 2007 KSPT to get an estimate of lost yield potential. The performance of the varieties in 2007 shows an even greater yield loss than what was predicted in 2006.
(Based on performance in 2007.)

25. Large Strip Trials, Populations Hardin County, 2006
Replicated strips
50K, 100K and 150K seeds/acre
3.9 maturity, full season
Bob Wade, Jr., Back Forty Farms

26. Previously Recommended Seeding Rates
Row Width (inches)
Seeding Rate
(seeds/acre) 7
119, ,000 15
139,000 – 167,000 30
111,000 – 139,000
AGR-130  SOYBEAN PRODUCTION IN KENTUCKY PART III: PLANTING PRACTICES AND DOUBLE CROPPING James H. Herbek and Morris J. Bitzer, Department of Agronomy

27. Cost of Soybean Populations
RR Seed
(seeds/acre)
(bu/acre)
($/acre)
100,000
0.56 20
120,000
0.67 24
150,000
0.83 30
180,000
1.00 36
200,000
1.11 40
Assuming 3,000 seeds per pound
$30 per 50 lb bag (RR Seed)

28. 1 2
34,800
121,800
17,400
70,000
192,000 3 4 5

29. Minimum Plant Population1
Minimum plant densities required for optimum yield
Seeding Date
Cultivar
Maturity
Minimum Plant Population1
plants/acre
24 April 03
full season
Stressland
4.5
42,500
CF 461
4.6
53,400
CF 492
4.9
49,800
21 May 04
B283
2.8
92,300
B336
3.3
72,100
CF461
85,800
21 June 04
late
91,400
93,100
1 Exponential rise to maximum, 3 parameter model: density required for 95% of yield that was achieved at maximum plant density.
Lexington, KY, 2003 and 2004

30. Population Effect on Yield Dry Weather, 2005
Full Season
Late Planting
B283
B336
Population
Yield
(seeds/acre)
Bu/Acre
17,400
17.1
23.9
27.1
28.8
34,800
35.5
33.4
33.6
70,000
15.6
38.0
38.7
121,800
16.3
35.6
49.4
44.3
192,000
12.0
31.2
50.1
46.5
U.K. Spindletop Farm
Lexington, KY
3 replications
2005 Growing Season

31. Soybean Population Study (Princeton UKREC, 2005)
Seeding Rate
(viable seeds/A)
Avg. Final Stand*
(Plants/A)
Soybean Yield**
(Bushels/A)
50,000
45,000
73 a
75,000
65,000
72 a
100,000
85,000
75 a
125,000
110,000
150,000
130,000
74 a
175,000
200,000
225,000
195,000
*Avg. approx. final stand of two varieties.
**Avg. of two varieties (3.9 RM and 4.7 RM). Varieties were not significantly different.
Planted May 25, Row spacing = 15 inches.

32. Light Interception: Soybeans
Shibles and Weber, 1965
(Fig. 2.3 in in Gardner et al Physiology of Crop Plants)

33. Light Interception: Soybean Plant Density
Arkansas (36°5' N)
Fig. 2. Fraction of light intercepted at 11, 22, and 46 d after emergence (DAE) was regressed against population density for ‘Manokin’ (MG IV) soybean at Fayetteville, AR, in 1999, using a monomolecular model .
81,000
162,000
Fig. 2, Purcell et al Crop Sci. 42:

34. Average of 29 years of weather data, Spindletop Farm, Lexington, KY.
Standard deviation: measurement of variation, expressed by bars.
Flowering dates generated from CROPGRO and verified from field data by Dr. Dennis Egli.

35. Large Strip Trials, Populations Hardin County, 2006
Replicated strips
50K, 100K and 150K seeds/acre
3.9 maturity, full season
Bob Wade, Jr., Back Forty Farms

36. 55.7 bu/a 53.3 bu/a 55.6 bu/a Hardin County Replicated strips
100K
52K
Hardin County
Replicated strips
50K, 100K and 150K seeds/acre
3.9 maturity, full season
Bob Wade, Jr., Back Forty Farms
Hardin County
Replicated strips
50K, 100K and 150K seeds/acre
3.9 maturity, full season
Bob Wade, Back Forty Farms
150K

37. 50 bu/a Worth and Dee Ellis Farms Photo taken: August 4, 2006
Full season planting
3.9 maturity?
Soybeans at R3
90K, 110K and 150K seeds/A

38. Current Recommendation
15-inch rows, full season soybeans
100,000 plants/acre final stand
Higher populations for DC soybeans

39. Row Spacing
Chad Lee, Grain Crops Extension, © 2006

40. Response of Full-Season Soybean Crops to Narrow Rows, Kentucky
*Data for each year has been averaged over varieties and/or locations. All plantings occurred before June 8.
Chad Lee, Grain Crops Extension, © 2006

41. Response of Full-Season Soybean Crops to Narrow Rows, Kentucky
*Data for each year has been averaged over varieties and/or locations. All plantings occurred before June 8.
Chad Lee, Grain Crops Extension, © 2006

42. Response of Full-Season Soybean Crops to Narrow Rows, Kentucky
*Data for each year has been averaged over varieties and/or locations. All plantings occurred before June 8.
Chad Lee, Grain Crops Extension, © 2006

43. Chad Lee, Grain Crops Extension, © 2006
Row spacing, Indiana 2006
Row spacing (inches)
Yield (bu/ac)
7.5
70.2 15
70.5 30
65.6
LSD (0.05)
2.3
Chad Lee, Grain Crops Extension, © 2006
Courtesy: Shawn Conley, Purdue University

44. Chad Lee, Grain Crops Extension, © 2006
[1] Louisiana, 30, 20 v. 40, (9); [2] Kansas, 38 to 39.84, 8 v. 30, (12); [3] Illinois, 40.12, 7.5, 20 v. 31, (6); [4] Nebraska, 40.5, 10 v. 30, (17); [5] Nebraska, 40.5, 20 v. 30, (17); [6] Nebraska, 40.5, 10 v. 30, (17); [1] Nebraska, 40.5, 20 v. 30, (17); [8] Iowa, 42.09, 10, 20 v. 30, (36);
[9] Ontario, 42.3, 10 v. 30, (1); [10] Michigan, 42.7, 15 v. 30, (10); [11] Michigan, 42.7, 7.5 v. 30, (10); [12] Michigan, 42.7, 7.5 v. 30, (25); [13] Wisconsin, 43.3, 7.5, 15 v. 30, (29); [14] Wisconsin, 43.35, 8 v. 30, (28); [15] Wisconsin, 43.35, 8 v. 30, (28); [16] Minnesota, 44.2 to 45.58, 10 v. 30, (23).
Lee, C. D Reducing row widths to increase yield: Why it does not always work. Online. Crop Management doi: /CM RV.
Chad Lee, Grain Crops Extension, © 2006

45. Chad Lee, Grain Crops Extension, © 2006
(B)
[1] Arkansas, 35.69, 7.5 v. 38, (5); [2] Arkansas, 35.69, 7.5 v. 38, (5); [3] Louisiana, 30, 20 v. 40, (9); [4] Kansas, 39.77, 8 v. 30, (12); [5] Wisconsin, 43.35, 8 v. 30, (3).
Lee, C. D Reducing row widths to increase yield: Why it does not always work. Online. Crop Management doi: /CM RV.
Chad Lee, Grain Crops Extension, © 2006

46. Row Spacing 10 Environments (2004-2005) Iowa
LSD 0.05 RS = 1.7 bu
LSD 0.05 RS X PPA = NS
Chad Lee, Grain Crops Extension, © 2006
© Palle Pedersen

47. Row Spacing Effect on Soybean Yield in Wisconsin (1997-1999)
Chad Lee, Grain Crops Extension, © 2006
© Palle Pedersen
(Bertram and Pedersen, 2004)

48. Chad Lee, Grain Crops Extension, © 2006
Light Interception
The crop must produce sufficient leaf area to intercept light completely as early as possible for maximum yields.
Ball et al. 2000b
Chad Lee, Grain Crops Extension, © 2006

49. Yield Cost of Delaying Weed Control in Soybean:
Cost = 2-3% in soybean yield loss for every crop leaf stage of delay
Chad Lee, Grain Crops Extension, © 2006
© Palle Pedersen

50. Time of Removal in Soybean
Row spacing Weeds must be removed by
(inches) soybean growth stage DAE
7.5” V days
15” V days
30” V days
V1 = 1st trifoliate
V2 = 2nd trifoliate
V3 = 3rd trifoliate
V4 = 4th trifoliate
Chad Lee, Grain Crops Extension, © 2006
© Palle Pedersen
(Stevan Knezevic, UNL)

51. Questions?