Growing High Yield Soybeans  01/17/14 11:22:13 AM

How do you raise seventy to eighty+ bushel soybeans? 
This is a somewhat mysterious and elusive process with soybeans, and it is annually debated this time of year.  Weather plays a massive role in this equation.  But, putting yourself in position to take advantage of timely weather events to maximize your yield potential is always worth reviewing.
There are instances where high yield goals have been reached.  How high is high?  Genetically it has been proven that a person can raise over 150 bushels to the acre.  Is that level of achievement feasible for the average Cass Co. acre?  Probably not, however, higher yields are attainable, with certain requirements needing to be met in order to attain this level of production.  Variety Selection, Soil Testing, Row Spacing, Scouting—weed, insect and disease management, tillage practices, seeding rates and planting dates are all important.  Remember this is a recipe that depends on everything mixing together to produce the high yield goal.
For this conversation I am going to factor all aspects of the weather out.  All of us agree that weather conditions on irrigated or dry-land acres make a huge difference in yield potential.  Nether you or I can control this aspect of crop production so let’s focus on working on what we can control.
SOIL TEST—FERTILITYOne must feed high yielding soybeans.  Our recommendations—addresses lime issues first and then focus on phosphorus and potassium levels for higher yielding soybeans—strive for Phosporus P1 levels from 25 to 30 ppm and potassium levels at or above 200 ppm. ---Research in the Southeast U.S. has shown the single most yield-limiting factor is soil acidity (low pH) This data indicates that growers are not addressing the lime needs of soybeans. Soybeans are more sensitive to high levels of soil acidity than most other field crops..  For most of our soil types in this area, a soil pH of 6.2 to 6.5 is optimal. This is a long-term program.  It will take a few years to establish a baseline fertility program to achieve higher yield goals—this is also one of my redundant statements for both corn and soybean production.  Fertility is indeed of major importance along with soil type when growing your yield potential. 
There are a number of versions of the following table.  Academics and private companies alike have their own perspective on what a crop nutritionally needs on a per bushel basis.  Some are more conservative than others.  This one is somewhat in the middle of the road.
Nutrient Removal for Soybeans  
Soybean nutrient requirements    
(Soybean yield of 70 bushels/acre)  
  Removed Remaining Total
  in Grain    in Stalks  
Nutrient    Pounds       Per Acre
Nitrogen (N) 266 77 343
Phosphorus (P2O5) 59 17 76
Potassium (K2O) 91 70 181
Sulfur (S) 13 12 25
Zinc (Zn) 0.08 0.32 0.40
Source: IPNI and Mosaic      
Most all of the nitrogen required is supplied through the soil and the atmosphere through symbiotic fixation.  Soybeans fixate approximately 1 lb of Nitrogen into the soil for every bushel of grain produced.
Using the above table for reference—If you want to raise 70 bushel soybeans, you need to supply, via soil credits or application, the above fertility requirements.  So, as a starting point, how much does your soil have of N, P, K, S and Zn in reserve? 
CONSERVE SOIL MOISTURE—Minimize tillage passes.  We realize that there are some soils (river bottom—gumbo) which require some tillage on an annual basis in order for them to be productive.  Some tillage may be required to warm up the soil on earlier plantings.  Soybeans, by weight use more soil water than corn does in order to emerge from the soil.  A soybean crop will produce approximately 2 bu/ac for every inch of water it uses through the season.   Hence, the need to conserve as much soil moisture as possible.  Disking is the worst form of tillage when it comes to soil moisture loss and tearing down the soil structure.
VARIETY SELECTION is probably the most important part of this equation.  Pick established, proven and well documented genetics—3.3 to 3.8 maturities work well in our geography.  Replicated data from multiple locations is best.  Select varieties with total agronomics for in-field flexibility, fast emergence and vigor, high disease tolerance, etc. 
My Suggestions—Asgrow AG3332, AG3432, AG3731, AG3832.  
I realize that there are many brands and varieties that offer genetics that “work”.  Do you know what you are getting from those genetics and is there credible, multi-year data to back it up?   
PLANTING DATE AND POPULATION-- always a debatable topic.  Our rule of thumb is to plant earlier than later.  If we could plant all soybean acres on one date in this area it would be May 5th…Why May 5th?  The soil in SE Nebraska is normally warm enough at planting depth to emerge the soybeans within 5-7 days on or about May 5th.  Academic data suggests that you should have them in the ground prior to May 1st is order to maximize node and pod production  If you can get them in early—fine—just be aware of the soil temperature (should be in the low 50’s at least) when you start and make sure it is continuing to climb on a daily basis during your planting window.  Ideal Population?  We think there is more than one reason growers select a specific soybean population,  Heavier populations canopy quicker, grow taller, are more efficient in water utility, provide additional competition during weed control—can delay late season herbicide applications, along with other things.  Soybeans do compensate for lighter populations.  That is un-debatable.   We have had the most success with final stands in the 150-160,000 range.  On average, this means a planting population of 160-165,000 is required Depth—planting them into to moisture is critical for emergence—within reason.  In an effort to plant to moisture in a dry spring you may be tempted to plant deeper.  I wouldn’t plant them much past 2”.  Soybeans deeper than 2” run an increased chance of stand loss, soil crusting over prior to emergence, as well as increased insect and disease pressure.  Moisture is critical, however, earlier planted soybeans have a much better chance of being planted into moisture at normal depth and achieve emergence within the desired 5-7 days.   1.5” planting depth is generally the norm.   BIGGER SEED = BIGGER YIELD There is no scientific data that we are aware of that agrees with this statement.  Smaller seed (3000 seeds/lb or more)  has just as much yield potential as big seed (2500-3000 seeds/lb).  Smaller seed may struggle for seedling establishment and vigor if planted too deep.
ROW SPACING—Our opinion is that to achieve constant high yield potential in soybeans, you need to be in less than 30” rows.  Debatable on what is the “best”.  I haven’t conducted any local tests however, research from multiple academic and machinery studies throughout the corn belt the past few years indicated a faster canopy, better UV light interception, increased soil moisture conservation, and early flowering which equated to higher yields in row spacing less than 30”.
WEED CONTROL—Certain species of weeds have become harder to control if not resistant to Roundup Ready applications.  We won’t debate whether they are or aren’t Roundup Resistant—they have become harder to kill lately with treatments we used a few years ago.  In light of this development, we are really going back to the days before the Roundup Ready era began (pre 1996) when it comes to making herbicide recommendations.  Single applications of Roundup and Roundup only are a thing of the past.  Trying to get ALL your weeds in a single application always has and always will be a challenge to say the least.   Our suggestion is this.  Use a dual-mode pre-emergence application either in the fall or early spring.  This is not iron-clad but it does buy to time to get a close to canopy application applied.  In the seedling stage of soybean development, competition with grasses and large seeded broadleaves had been widely documented to reduce viable stand, use soil moisture, and reduce yield potential regardless of the population and planting date.   Follow your pre-emergence application with a Roundup based post-emergence treatment.  You likely will have to consider a tank mix to pick up any volunteer Roundup Ready corn or additional broadleaves that still may be present.  
PEST SCOUTING—We would always scout first.  Most producers know however, through past experiences, general weed, insect and disease pressure on acres they have farmed for a number of years. HERBICIDES-- Blanket strategies--I would always consider pre-emergent herbicides for weed control—it buys you time to get the crop closer to canopy prior to post-emergence applications, conserves soil moisture, and allows early and active soybean seedling growth to occur.  Additionally, I would always consider a seed treatment.  It is hard to argue the data over the past few years that a seed treatment isn’t worth your
investment.—See below
Year   2009 2010 2011 2012 2013
Crop   Soybeans Soybeans Soybeans Soybeans Soybeans
Treatment Cruiser Max Cruiser Max Cruiser Max Cruiser Max Cruiser Max Advanced
Rate   3 oz /cwt 3 oz /cwt 3 oz /cwt  
3 oz /cwt
3.2 oz /cwt
No. Trials   3 3 5 15 17
Yield Difference Plus 6 bu/ac Plus 4.9 bu/ac Plus 1.4 bu/ac Plus 2.3 bu/ac Plus 2.1 bu/ac
Soybean Price $9.50/bu $9.50/bu $11.00/bu $13.00/bu. $12.00/bu.
Gross Difference/A $57.00 $46.55 $15.40 $29.90 $25.20
Net Diff. -$13.00 Trt $44.00 $33.55 $2.40 $16.90 $12.20
  5 year average advantage  of 3.34 bushels per acre = $21.81 Net Ave.
In-season weed, insect and disease control is a bit trickier as treatments need to be designed for the pest at hand.   In season scouting documents pest threshold and establishes whether or not you should budget for a treatment.  FOLIAR FUNGICIDES--More inconsistent in what the data shows.  Soybeans are funny to figure out sometimes due to their adaptive abilities to adjust to growing environments.  We do believe in the increase in plant health with fungicide applications even in the absence of a threshold level foliar disease.  Below is our data for the past 5 years.
Year   2009 2010 2011 2012 2013
Crop   Soybean Soybean Soybean Soybean Soybean
Treatment Quadris + Quadris + Quadris + Quadris + Quadris +
    Endigo Endigo Endigo Endigo Endigo
Rate   6 oz Quadris + 3.5 oz Endigo + 0.5 pt Between    
No. Trials   3 3 6 6 6
Yield Difference Plus 11.52 Plus 7.79 Plus 3.2 Plus 1.67 Plus 3.3
    Bu.Acre Bu.Acre Bu.Acre Bu.Acre Bu.Acre
Soybean Selling Price $9.50/bu $9.50/bu. $11.00/bu $14.00/bu. $12.00/bu.
Gross Diff./Acre $109.44 $74.00 $35.20 $23.38 $39.60
Net Diff. -$30 Trt $79.44 $31.20 $20.30 ($6.62) $9.60
  5 year average advantage of 5.5 bushels = $26.79 Net Ave.
John W. McNamara
Wiles Bros. Inc.
606 Wiles Road
Plattsmouth NE. 68048
(402) 298-8550--Office
(402) 499-3870--Cell
(402) 298-7174--Fax
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