February 2008 GA Soybean Update-Woodruff
Georgia farmers are showing more interest in soybeans than in several years. And
rightfully so, Nov ’08 soybean futures are trading above $12/bu, well above the last five year
average. On paper, soybeans show good profit potential, $100-$250/A over variable costs, even
with current high energy, seed, fertilizer and other input costs.
What can we expect going into the 2008 season?
1. The majority of 2008 Georgia soybeans will be double cropped. Georgia farmers currently
have about 475,000 acres of small grain, 100,000 acres of winter grazing and 25,000 acres
of vegetables planted. We anticipate that at least half of these acres will be planted to
soybeans this summer. Georgia farmers will likely plant at least 100,000 acres of fullseason soybeans, and will likely irrigate 20-25 percent of 2008 plantings. It appears that
there will be upwards of 400,000 acres of Georgia soybeans this year. If realized, this will
be the largest Georgia soybean crop since the 1990’s.
2. Seed supply will be short, especially for late maturing varieties. The soybean seed
industry anticipated some expansion of soybean acreage, and increased seed production.
But current soybean interest has exceeded all expectations. The bottom line is that we are
facing a soybean seed shortage for the late maturing varieties, those especially needed for
the double crop plantings. Early maturing soybean varieties may be substituted for late
maturing varieties when planting on productive soils, planting before June 10, and/or when
planting in close rows. Letting seed needs be known to seed dealer and exploring
suitability of given varieties to field situations will be important this year.
3. Market prices should decline. A large South American soybean crop should start entering
the market place by late March and April. This along with an expected increase in US
farm soybean plantings should start putting downward pressure on soybean prices by
summer months unless adverse weather problems develop in a major soybean production
area. In light of this likely landscape, it seems prudent to make some forward contract
sales to take advantage of current high prices. Because soybean yields are highly variable,
it would be wise to not forward contract more than about 1/3 of expected dryland
production and ½ of expected irrigated production.
4. Developing a good soybean production plan will be important to success. Much of the
improved soybean profit potential will be in making above average yields. The planning
process now for above average yields should include:
a. Site-Is the soil productive? Does it have nematodes or other pests?
b. Soil-pH/fertility-Are these suitable for soybeans? Do I have a soil test? Will I
need an inoculant to insure good nitrogen fixation?
c. Soil compaction-Will deep tillage be needed? Can I avoid re-compacting the soil
during land preparation and planting?
d. Planting date-Can I plant on time? If not, what variety and cultural adjustments
should I make?
e. Soybean variety-What are some good varieties for this field? Can I get seed? Does
the seed have good germination?
f. Drought-What can I do to reduce these losses?
g. Weeds-Do I need a “burn down” herbicide? Do I need to tank mix something with
glyphosate to get improved weed control? Can I make timely applications
h. Insects-How will I scout fields? Do I need a Dimilin/boron treatment? What
insecticides should I use?
i. Soybean rust-Will it be a problem in 2008? How can I stay abreast of the status of
soybean rust? When will I need to make treatment? What will I need to control
rust and other foliar soybean diseases?
j. Harvest-Will I need a harvest aid? Can I harvest efficiently? Can I harvest on
time?
Helpful insight on these production questions can be found in the 2008 Georgia Soybean
Production Guide. This bulletin is available at the local county Extension office or can be viewed
on line at: www.caes.uga.edu/commodities/fieldcrops/soybeans
Higher Irrigated Soybean Yields Possible – Woodruff
Soil moisture stress is the number one soybean yield limiting factor in Georgia. Summer
drought has historically reduced Georgia soybean yield from 5 to 50 bu/A. The average dryland
soybean crop, outside river bottoms, will lose 25-30 bu/A yield due to soil moisture stress.
Moisture stress is a particular problem for Georgia soybeans because (1) the plant is not highly
tolerant of soil moisture stress, especially during the productive growth stages, (2) each soybean
variety has a “critical period” when it must get moisture to produce good seed yield, (this critical
period of 6-7 weeks occurs from early to late summer depending on earliness of variety and
planting date) and (3) extended dry periods which frequently occur across Georgia from August to
November.
Average good efforts to irrigate soybeans usually result in yields of 50-55 bu/A for full
season and 40-50 bu/A for double crop soybeans. At current market prices, there is pretty good
profit in average efforts, but such irrigated efforts in years past have not made soybeans
competitive with other crops for available irrigated land.
It is now possible to produce 60+ bu/A soybeans more consistently than ten years ago.
Some things making this possible include:
1. New Improved Soybean Varieties. Top yielding RR recommended soybean varieties are
often exceeding 70 bu/A, see table below. When RR soybean varieties first became
available 10-15 years ago, they lagged conventional varieties in yield. Today, they appear
to have a slight yield advantage over conventional varieties. Note from the table below that
early maturing varieties tend to out-yield late maturing varieties. Using early varieties for
good soils and early plantings with close rows can be a way of getting more soybeans. But
late maturing varieties are still preferred choices of planting on less fertile soils and
planting late or planting in wide rows.
2. Good Irrigation Scheduling. Soybeans can tolerate some moisture stress during
vegetative growth but must receive adequate moisture during the critical period for top
yields. The soybean critical period occurs from the time of full bloom (R2) until full pod
development (R6). Duration of the critical period is 6-7 weeks. During this time irrigation
should be used to supplement rainfall weekly to keep soybean leaves from wilting. Before
and after the critical period irrigation should be used a bit more sparingly if soybeans show
signs of wilting by mid-day. In average years, soybeans will require 6-10 irrigation
applications. Late maturing soybean varieties will usually require 1-2 more applications
than early maturing varieties.
3. Close Row Spacing. Most Georgia soybean plantings are made in wide rows (36”-38”).
Georgia research continues to show increased soybean yields with close row plantings, see
table 2 below. Our experience on sandy textured soils is that soybeans yield more with
wide rows when in-row subsoiling is used than when planted in close row spacings without
deep tillage. But where deep tillage can be done without re-compacting soil during land
preparation and planting, close rows will give 5-20% yield increase. Note from the Camilla
data below that there was more yield response for an early maturing variety than for a late
maturing variety to close row planting. Yield increase for close row planting is also greater
for late than early planting dates. What about twin row planters? We have no yield data on
these but would expect them to provide some yield increase over wide single row
plantings, especially since the benefits of in-row subsoiling can be attained.
4. Improved Pest Management Methods. We now have methods for getting better
soybean, weed, insect, and leaf disease than 10-15 years ago. The Roundup Ready
technology with RR varieties is definitely allowing for improved weed control with less
soybean injury. The Dimilin boron treatment of R3 often gives some soybean yield
enhancement while providing season long control of velvetbean caterpillars. The new
foliar fungicides used for controlling Asian soybean rust frequently is giving soybean yield
enhancement even when rust is not obvious.
5. Good Basic Culture. These efforts will help get increased soybean yield. But most
important, is using good basic soybean culture. Practices such as crop rotation,
conservation tillage, good soil pH/fertility, based on soil test recommendations, timely
planting and culture, seed inoculant, and timely harvest are all crucial to getting top
soybean yields. The 2008 Georgia Soybean Production Guide for details on all aspects of
high yield soybean production. It is available at the local county Extension office or can
be viewed on line at: www.caes.uga.edu/commodities/fieldcrops/soybeans
The new varieties and methods won’t guarantee 60+ bushel soybeans but they usually increase
soybean yield and are worth trying.
Table 1. TOP RR RECOMMENDED SOYBEAN VARIETIES
HOW THEY PERFORMED IN TIFTON AND PLAINS 2006-2007
Soybean Variety
Location
& Maturity Group
Variety and Year
Tifton
Plains
2006
2006
2006
2007*
2 Year Average
MG V
AGS 568 RR
AG 5905
DP 5634 RR
RT 5540 N
RT 5760 N
RT 5930 N
RT 5951 N
USG 7582nRR
MG VI
AG 6702
DP 6568 RR
Pioneer 96M60
RT 6202 N
RT 6451 N
RT 6600 N
USG 620nRR
USG 7635nRR
MG VII & VIII
AGS 758
AG 7601
DP 7220RR
DP 7870 RR
DP 7330 RR
DeKalb H7242 RR
NK 578-G6
NK 580-P2
72.5
74.4
69.8
66.0
69.9
58.6
71.3
70.5
69.1
65.7
74.5
59.1
70.7
68.7
71.6
68.5
66.4
68.2
69.2
69.6
64.4
69.5
69.2
70.0
63.5
70.5
68.2
59.5
55.9
42.1
45.5
59.4
54.1
44.2
49.2
51.2
66.7
68.6
58.9
63.0
66.8
63.6
61.9
64.2
64.2
65.8
71.4
55.5
70.3
73.7
68.0
73.1
71.5
68.7
65.7
62.3
58.4
67.7
63.6
58.3
66.2
69.1
63.9
60.0
65.5
60.4
64.5
57.5
56.5
64.0
62.3
61.3
58.9
45.4
39.5
54.2
53.6
51.1
48.8
53.2
50.6
62.9
61.2
53.5
64.2
62.1
58.5
63.0
64.0
61.1
58.1
55.9
70.1
51.6
46.9
53.0
64.6
59.0
50.1
59.9
51.6
59.2
45.8
56.7
51.4
53.5
48.6
53.3
55.6
54.7
61.0
58.0
61.1
61.0
60.3
61.5
59.2
51.6
47.6
47.3
47.4
52.0
48.4
52.0
46.5
55.1
56.3
52.5
59.4
50.7
54.2
53.5
57.6
53.9
54.8
* Top yields were not obtained at this site and year due to severe drought and irrigation
challenges.
Stripling Center Soybean Yield Results – 2007
- Woodruff
Table 2. Yield of Early (AGS 568) and Late (AGS 758) Soybeans With Wide (36") and Narrow (24") Row Spacings
When Receiving (1) No Irrigation, (2) 60% Irrigation, (3) 120% Irrigation, and (4) 60% Irrigation During Vegetative
Growth and 120% Irrigation During Reproductive Growth, 2007, Stripling Irrigation Research Park, Camilla, Georgia
1
W
N
REP
1
2
3
4
AVERAGE
42.6
72.1
46.5
56.1
61.4
71.9
57.8
71.1
54.325
65.55
AGS 568
IRRIGATION TREATMENT
2
3
W
N
W
N
Yield (bu/A)
56.9
73.8
78.7
77.4
68.5
73.3
75
75.5
83.5
80
66.3
69
70.4
75
54.9
79.9
69.825
75.525
68.725
75.45
4
W
AVERAGE
(bu/A)
N
68.7
76.7
63.4
58.8
72.6
70.2
69.7
66.8
66.513
72.900
67.025
66.625
66.9
69.825
68.266
Average for row width
Wide =
64.950
Narrow =
71.590
1
W
N
REP
1
2
3
4
AVERAGE
46.5
61.7
55.4
57.1
63.6
61.2
65.1
64.9
55.175
63.7
AGS 758
IRRIGATION TREATMENT
2
3
W
N
W
N
Yield (bu/A)
63.6
70.9
63.9
73.3
70.2
64.6
71.1
68
66.8
63.2
69
70.4
62.7
67.5
68.2
69
65.825
66.55
68.05
70.175
4
W
AVERAGE
(bu/A)
N
64.9
69.2
69
63.9
73.8
69.2
70.4
65.4
65.063
66.900
66.163
64.838
66.75
69.7
65.741
Average for row width
Wide =
63.950
Narrow =
67.530
Irrigation Treatments
1. No irrigation except watering to get emergence.
2. 60% irrigation all season
3. 120% irrigation all season
4. 60% irrigation during vegetative growth, 120% irrigation during reproductive growth
Reducing Risks of Double Crop Soybeans - Woodruff
According to NASS, 77 percent of 2007 Georgia soybean plantings were planted double crop
mostly after small grains and winter grazing. Georgia had a generally favorable season for 2007
double crop soybeans but such plantings are often at risk for low yield due to late planting,
adverse soil conditions for getting a good soybean stand, drought, and heavy pest problems. A
high percentage of 2008 Georgia soybean plantings will likely be double cropped also, as there
are currently more than 600,000 combined acres of small grain, winter grazing and vegetable
plantings. Average double crop efforts usually result in 20-25 bu/A soybeans for dryland and 4050 bu/A for irrigated soybeans. Above average management effort can increase these yields by 1530%. Here are some things that can help improve double crop soybean yields.
1. Harvest winter crop early and plant double crop soybeans as early as if feasible.
The ideal planting window for soybeans is from May 10 to June 10. There is usually
opportunity to get the winter crop harvested and some soybeans planted before June 10.
But unfortunately, due to distractions and the many on-going farm activities, the average
double crop soybean doesn’t get planted until June 15. Research has shown that soybean
yield usually declines about 1/3 bu/A/day for every day planting is delayed after June 1.
Hence, the average double crop planting has already given up 5 bu/A before planting
begins. Delay soybean planting, though, if seed can not be placed in moist soil. Careful
planning to get timely winter crop harvesting and early double crop soybean planting can
be most important to double crop soybean success.
2. Use minimum tillage to speed up double crop soybean planting and to conserve soil
moisture. For Limestone Valley and Piedmont soil no-till precision seeders generally work
well. But for most Coastal Plain soils, strip tillage, with in-row subsoiling is a must for
getting increased yields. Minimum tillage can help get timely planting after the winter
crop and allow for planting in a more favorable soil environment if old crop litter can be
kept out of the seed bed.
3. Get rid of established weeds before/when planting double crop soybeans. Summer weeds
often get established as winter crops mature. Controlling these weeds with standard PO
soybean herbicides can be expensive or impossible. UGA weed scientist, Dr. Eric Prostko
recommends using a PE burn down herbicide to control established weeds.
4. Make sure soil nutrient needs are adequate for soybeans. Most farmers apply P and K
ahead of the winter crop planting expecting the fertilizer application to meet the needs of
both the winter and summer crop. The only problem here is that growers often do not apply
enough nutrients, especially K for soybeans too. This problem gets really exacerbated
when small grain straw is baled and removed from the field (see Glen Harris’s article in
this newsletter). Baled straw will usually remove more than 100 lbs/K2O per acre. To
adequately grow soybeans where both grain and straw are removed will require rather high
K fertilization. Cash income generated from straw sales will often be more than offset by
soil K removal. If in doubt, get a soil test, and fertilize accordingly.
5. Plant a soybean variety appropriate for planting date. Do everything possible to get double
crop soybeans planted before June 10. When this is accomplished any variety
recommended for the area should be good. The very early maturing MG V soybean
varieties will also benefit from close row plantings (see irrigation article with this issue).
Plant double crop soybeans early only as favorable soil moisture conditions allow. Do not
“dust in” or plant soybeans in dry soil. Such usually results in very poor stands. When
necessary, wait for a good soaking rain before planting double crop soybeans. This will
happen often, so plan for double crop soybean varieties that are suited for late planting. In
North Georgia, these will be MG VI and VII varieties. In South Georgia, these will be MG
VII and VIII varieties. See the UGA 2008 recommended soybean variety list for varieties
that should perform well for your location and planting date.
6. Plant in close rows if such can be done without compromising benefits of in-row
subsoiling. Late planted soybeans will usually have highest yields when planted in row
spacings of 15-30 inches. In the Coastal Plain, wide rows with in-row subsoiling will
usually out perform close rows where soil compaction is a problem. Using twin-row
planters may be a way of getting some of the benefits of close-rows without giving up
benefits of in-row subsoiling.
7. Start insect scouting by checking for lesser corn stalk borers and cut worms during
soybean vegetative growth stages. Know the conditions under which these insects thrive.
Hot, dry conditions favor the lesser corn borer. Such conditions frequently occur,
especially with June or late plantings. Lesser corn stalk borers outright kill seedling
soybean plants (<1 month old) and girdle older plants stunting them and often causing
slow death. Cut worm problems are usually favored when there is lots of fresh decaying
organic matter such as where green vegetables have been harvested or where other green
vegetation has been incorporated into soil ahead of soybean planting. Preplant soil
insecticides are generally not effective for controlling these insects. But there are some
insecticides effective for controlling the small larvae of these two pests. See the 2008
Georgia Pest Control Handbook for recommendations.
8. Irrigation can be especially beneficial for double crop beans. If needed, irrigate ahead of
soybean planting to get soybeans planted on time. Use irrigation as needed to get fullcanopy development by first bloom. Depending on variety, 2-3 water applications during
vegetative growth may be needed. From full bloom-full pod fill (R2-R5) supplement
weekly rainfall so that soybeans do not stress for moisture. Irrigate an additional 1-2 times
during R6 if leaf wilting occurs by mid-day.
The Value of Wheat Straw: Baled or Burned - Harris
Two common options for dealing with wheat straw in double-cropping system are baling or
burning. Baled wheat straw, removed from the field, removes a considerable amount of nutrients.
The amount of nutrients contained in wheat straw from a 60 bu/a crop are estimated as follows:
N
P205
K20
Mg
S
---------------------------------------------lb/a--------------------------------------------34
8
108
9
12
With current fertilizer prices of 60 cents/lb of N, 50 cents/lb of P, and 35 cents/lb of K, this straw
would have a value equivalent to$62/a. Most of the value is split evenly between N and K. Also,
the value of Mg, S as well as micronutrients may add an additional dollar or two to the total.
A considerable amount of nutrients are also contained in the harvested wheat grain.
Approximately 72 lb N, 33 lb P, 20 lb K, 9 lb Mg and 4 lb S are removed for every 60 bu of grain.
While these removal figures are interesting and important to know, fertilizing crops based on
removal figures is cautioned. The reason why removal figures alone should not be used to guide
fertilization is that even though a certain amount of nutrients are removed, the soil may still have
the capacity to supply nutrients to the following crop. The best way to determine if this supplying
capacity is present is with a soil test. Even in a wheat-soybean double-crop system, it is advisable
to take a soil sample between the wheat and soybean crop. This will assure adequate fertilization
of the soybean crop, especially with K. Notice that the amount of K removed in wheat straw is
high. Add to this that K is relatively mobile in soil, the cost of a soil test for guiding potassium
fertilization of double crop beans alone is justified.
Burning wheat straw and residue before planting double-cropped beans is another practice
sometimes used. However, this practice is discouraged for a number of reasons.
First of all, burning wheat straw will still return P and K to the land in the form of ash, but
nitrogen is lost in the process (it literally “goes up in smoke”). Since N accounts for about half of
the value of wheat straw nutrients, about $20/a are lost in this process, cutting the value from $60
to $40 per acre.
Another even more important reason not to burn wheat straw is that all of the carbon or organic
matter associated with the straw will be lost. Incorporating crop residues is one of the few ways to
maintain the already low organic matter content of our Coastal Plain soils. Granted, it is difficult
to put an exact dollar figure on this organic matter. However, it is commonly accepted that
organic matter in soil will increase water holding capacity, nutrient holding capacity and overall
productivity of a soil.
In conclusion, think abut the nutrients contained in wheat straw, know the
dollar value, and keep the lighter in your pocket.