Seeding Rates

1
Soybean farmers in South Carolina
consistently produce a 20 bu/A crop. Why? Where
do we go from here?
2
Survey of Soybean Production Practices in South
Carolina

• Jason Norsworthy
• Clemson University

3
Objectives

• To determine specific research focus areas for
  Clemson scientists.
• To identify production practices that can be
  altered to reduce risk and/or increase economic
  return.

4
Objectives

• To establish a baseline so that changes in
  production practices can be assessed.

5
Top Five Research Requests

• 25, Improved weed control
• 18, Nematode-resistant varieties
• 16, Higher yielding varieties
• 9, Drought tolerant varieties
• 7, Clemson Roundup Ready varieties,
  Insect-resistant varieties, Drilled soybean
  populations

6
Total Acreage Surveyed
Written Survey 43,000 Acres
Field Survey 24,000 Acres (13 Counties)
7
What pest most limits your yield?
Weeds, 57 Nematodes, 24 Insects, 19
8
List two most troublesome weeds
69 sicklepod (coffee weed)
61 Palmer amaranth (pigweed)
33 mornningglory spp.
5 nutsedge spp.
lt5 Texax panicum, com. cocklebur, com.
ragweed, com. lambsquarters, redweed,
johnsongrass, Pennsylvannia smartweed,
broadleaf signalgrass, arrowleaf sida
9
Weed Management
10
Postemergence herbicide applications need to be
applied based on weed density and size.
As late as possible Whenever Im able to get
back to the field Guess Good thick
flush Once a dense soybean groundcover is
established Soybean size Number of days after
planting
11
Most Troublesome Weeds
1 sicklepod
12
Most Troublesome Weeds
2 Palmer amaranth
13
Most Troublesome Weeds
3 Morningglory spp.
14
Benefits of Herbicide-Tolerant Soybeans

• Broad-spectrum weed control

• High level of crop safety

• Widened application window

• Herbicide-resistant weed management

• Increased crop rotation flexibility

• New weed control strategies for
• conservation tillage systems

15
How do we determine if a postemergence herbicide
application (Roundup Ultra) would increase net
returns?
16
Soybean Yield Loss from Pitted Morningglory
17
10 Yield Loss, Soybean price 6.00/bu, Roundup
Ultra Application 14.00/acre
Projected Yield
Gross Return
Yield Loss
Cost
Treat
20 bu/A 2 bu/A 12.00 14.00 No 30
bu/A 3 bu/A 18.00 14.00 Yes 40
bu/A 4 bu/A 24.00 14.00 Yes
18
Benefits of Drill-Seeded Soybean Shortened
weed-free requirements Increased herbicide
effectiveness Suppression of uncontrolled
weeds Suppression of late emerging weeds Greater
seed yield
19

• What percentage of farmers are growing Roundup
  Ready soybeans?
• 68

20
What percentage of the total soybean acreage is
planted to Roundup Ready soybeans? 55
21
What percentage of Roundup Ready soybeans
receivedone glyphosate application?
47
22
What percentage of wide-row Roundup Ready
soybeans received two or more Roundup
applications?
67
23
What percentage of Roundup Ready soybeans were
planted in narrow rows (lt 20 inches)?
48
24
What percentage of these farmers used
a preemergence herbicide? 31
25
What percentage of farmers are planting soybeans
in row widths lt20 inches?
42
26
What percentage of narrow-row Roundup Ready
soybeans were treated twice?
48
27
What percentage of the soybean acreage is double
cropped? 49
28
For late planted, drilled soybeans, a yield
increase of 10 to 15 over wide-row soybeans can
be expected.
Drilled
Wide
Drilled
Wide
Drilled
Wide
1 WAE
4 WAE
7 WAE
29
What percentage of Roundup Ready narrow-row
soybeans received a soil-applied herbicide?
39
30
Do soil-applied herbicides reduce the number
of in-crop Roundup applications?
without soil-applied herb. - 44
with soil-applied herb. - 70
narrow row widths, single application
31
Seeding Rates
32
Yearly Purchase of Seed
Technology fee/bag
33
What is the optimum drilled seeding
rate? Optimum yield? Economic optimum?
34
3 plants/ft for drilled soybeans ? 250,000
seed/A (85 emerg.) ? 83 lb/A (3,000
seed/lb) ? 42/A
35
Seeding Rates
Roundup Ready
Conventional
36
Seeding Rates
Narrow row (lt 20 inches)
Wide row ( gt 20 inches)
37
Weed Management Recommendations

• Dont let Palmer amaranth get away from you
  (timely application).
• If morningglories are a problem in Roundup Ready
  soybeans, tank-mix FirstRate with Roundup.

38
Weed Management Recommendations

• Four to six weeks of intense weed management is
  needed to optimize soybean yields, not weed
  control after four to six weeks.
• Look at using a residual herbicide applied
  preemergence or tank-mixed with Roundup when
  Roundup Ready soybeans are grown in wide rows.

39
Nematode Management
40
Are nematodeshigh on farmerslist of pest?
41
What percentage of farmershave nematode analyses
conducted?
16
42
What percentage of our soybeans are grown without
rotation?
38
43
What percentage of the farmers rotating soybean
with other crops utilize corn as the sole
rotational crop?
40
44
What percentage of farmers use nematode
resistance as a variety selection criteria?
58
45
Nematode Resistance in Commonly Grown Maturity VI
and VII Roundup Ready Varieties
46
What percentage of those farmers using nematode
resistance as a variety selection criteria also
use herbicide tolerance as a selection criteria?
65
47
What percentage of farmers have soil fertility
analyses conducted?
63
48
Nematode Management Recommendations

• Focus closely on resistance/tolerance when
  choosing a variety.
• Soybeans need to be rotated with other crops for
  long-term, profitable production.

49
Nematode Management Recommendations

• Have a nematode analysis conducted at least every
  other year.
• If Roundup Ready, wide-row soybean will be grown
  in nematode infested areas, consider placing a
  low rate of Temik (3 lb) in-furrow at planting.

50
Insect Management
51
What percentage of farmers are using
defoliation and economic thresholds to time
insecticide applications?
19
52
Insect Management Recommendations

• Intense scouting is needed during soybean
  reproductive development. You cant scout for
  pod-feeders from the truck.
• Treat at 30 defoliation during vegetative
  development and 15 defoliation during
  reproductive development.
• Use established thresholds.

53
Tillage
54
What percentage of farmers utilize some form of
conservation tillage?
43
55
What percentage of farmers are using deep tillage?
50
56
Variety Selection
57
Variety Selection
58
Maturity Group Use
of Farms Surveyed
Maturity Group
59
Use of Multiple Maturity Groups
60
Questions ?
61
Questions to Answer

• What percentage of the Roundup Ready soybean
  acreage receives multiple applications of Roundup
  Ultra? By row width?

62
Questions to Answer

• What percentage of the Roundup Ready soybean
  acreage utilized a soil-applied herbicide?

63
Questions to Answer

• What was the average weed control cost by row
  width, seeding rate, and transgenic variety use?
• Does row spacing preference vary by region of the
  state?

64
Maturity Group Use by Region
of Farms Surveyed
Maturity Group
65
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66
Ways to Maximize Soybean Profits in South Carolina
Narrow row widths Conservation and deep
tillage Variety selection Optimum seeding
rates
67
Irrigation
68
What percentage of the South Carolina soybean
acreage is irrigated?
4
69
Increased Returns with Irrigated Soybeans
70
Weed Management
Row width
71
Row Widths
72
The most critical period of weed control in
soybeans is the first month after soybean
emergence. (Burnside 1979)
73
Ways to Maximize Soybean Profits in South Carolina
Irrigation Aggressive marketing Timely weed
management Nematode management Insect management