Hello, my name is Shawn Conley, state soybean and small grain specialist at the University
of Wisconsin–Madison.
Today, we’re going to discuss many questions related to soybean growth and development,
how by understanding soybean growth and development you can make key crop management decisions.
To begin with, I want to lay the base framework for soybean yield and what it is the function
of.
If you look at soybean management and soybean yield potential, it’s a combination of genetic
yield potential, agronomic management, and environment.
If you look at many of the models predicted in describing soybean yield, you basically
can just parse the genetic yield gain over the last eighty years or so for soybean, based
on 50 percent genetic potential and 50 percent changes in agronomic management.
The genetic yield would be variety selection in that general 0.3 to 0.4 bushels per acre,
per year yield gain, just through breeding efforts.
Then, you combine that with agronomic management practices, such as earlier planting dates,
seed treatments, better soil fertility and pest management practices to give us the other
half of our genetic yield gain.
Of course, both of those factors–genetic yield potential and agronomic management–are
always trumped by the environment, be it the water, the temperature, or some other questions
related to climate change or climate variability in these years.
So, what we want to do is address how soybean management, and truly understanding growth
and development under these three frameworks, can help us better manage our soybean crop
moving forward.
Again, if we had to prioritize soybean yield varietal characteristics when you’re going
through and selecting variety, obviously if you look at what growers have paid for right
now, it’s on yield.
In a few short sides we’ll be discussing how to properly select a second variety, but
again we want to base most of our primary decision on yield.
The second decision growers need to understand is what are the disease resistance characteristics
that meet their needs and their demands in their specific fields.
Next, we’ll be discussing the maturity group limitations, or what maturity groups growers
should be selecting based on their geography within the state of Wisconsin.
Lastly, grain composition.
We are fortunate in the state of Wisconsin to have about ten to twelve percent of our
acres be food grade soybeans.
So again, in those situations, grain composition moves up right behind yield in terms of varietal
characteristics, so please contact your supplier if you’re working with grain composition
questions.
And lastly is lodging, the breeding efforts have really done a good job over the last
20 to 25 years of really limiting our lodging constraints and soybean production.
To claim what growers are really interested in, we took a survey five years ago amongst
several hundred growers, to really look at what are they looking for when they select
the soybean variety.
By far and away, they’re mainly dependent on yield potential.
After that is disease resistance, and then their interest is plus or minus a glyphosate
trait.
Those growers that are non-GMO or food grade are obviously going to be selecting for those
varieties that are not GMOs, or have that trait in it, where other growers looking at
simplifying it so that weed management strategies will be able to address and use some of that
trait to use glyphosate as a tool in their weed management system.
After that, dealer recommendations, and again seed price really falls down on the list.
And, based on that information, what you’ll soon see–I’ll agree with growers that
again they should be looking at yield potential first and not spending as much time addressing
the whole issue of seed price and make the decisions.
The other key characteristics I like to remind growers is over the same land based area,
an average number of soybean varieties a grower will pant will be 2.3 acres.
On the flip side, growers will normally plant 4.6 acres.
So one of the challenges I see with growers is they’re really limiting their genetic
yield potential, that they’re putting across their land based area by half.
That really minimizes their influence of variety selection.
So I strongly encourage growers, as we move forward into you know 2015 and beyond, to
really spend more time on focusing on the variety selection and also really pick more
than two to three varieties to help mitigate some of the environmental stress that we’re
seeing given some of these climate variability questions we are seeing today.
One of the key tools we like to talk to growers in the state of Wisconsin about is the Wisconsin
Soybean Variety Test Results, UW-Extension publication A3654.
This is a compilation of varietal results that is unbiased and takes all companies into
task to be able to identify which varieties across any company platform performs the best
over a wide range of environmental and geographical locations across the state of Wisconsin.
I want to quickly take you through how you would interpret this book in case you are
interested in downloading it from our web page, or you have access to it through many
of the multiple newspapers that published this article in early December.
If we go from left to right, we always have the brand and we identify these in alphabetical
order so it would be easy for a grower or crop consultant to go through and identify
and find the specific variety of interest.
Next, we have the entry, or the number, of that variety.
The third column is the maturity group, a relative maturity group, given to that variety
by the company.
The next title, or the next column is in the single year, multi-location yields, basically
what this is is a combination of all of the single site meet locations across a specific
region.
We also label the maturity dates that we recorded, and this gives growers an idea of when these
soybeans are physiologically mature.
So when they’re looking at the maturity group, they have a better decision on how
well that maturity group relates to that actual time when that soybean plant hits maturity.
We next have individual site year locations.
On this example we have Arlington, East Troy, and Platteville sites–which is in the southern
region–so it gives growers a sense of where the sites are, and individual performance
across those individual sites.
We also publish protein and oil composition for those growers in oil quality characteristics
in making their marketing decisions.
And, we finally publish the previous year’s results for those growers trying to get multi-year,
multi-location data.
Now, one of the things we provide with this is some of the statistics behind really understanding
if a variety is truly different than another one.
We have two specific things we like to address here.
First of all, is our LSD level.
So, in this example here, an LSD of 5 says that any two yields differing or equal to
5 bushels are significantly different.
If they are less than 5 bushels, they’re not statistically different, so it gives you
a sense of whether or not two specific varieties, if you’re trying to make a decision, are
truly the same or different.
In an effort to help facilitate and push growers or help growers easily identify the high-yielding
varieties, we have these yields that are preceded by a star, and these starred varieties mean
they’re not statistically different than the highest-yielding variety within a given
location or given region.
Again, this helps growers have a better understanding in order to help identify those high-yielding
varieties right off the bat.
So, one of the choices we also give growers is based on their latitude within the state
of Wisconsin, what relative maturity they should be planting.
So again, based on your county, based on what part of the state of Wisconsin you live, this
is a relative idea of what the relative maturity is.
So for an example, if you live in Dane County, or farm in Jefferson County, the optimal group
range you should be looking at, or deciding to plant in that specific region, is anywhere
from a 1.72 to a 2.5 maturity group soybean.
As you move further north, say to Marathon County, then that relative maturity shrinks
down from a 0.0 to 1.4.
Again, it helps growers make that decision and kind of hone in on what maturity groups
will best perform in their specific geographic region.
So, one of the things we were able to do, is by having this database of information,
understand what is the optimal soybean material group for yield.
So, we went through the last seven to eight years of our soybean variety trial book and
we were able to identify what is the optimal maturity group yield for those growers in
the southern region of Wisconsin, so again that would basically be from the northern
Dane County line, south.
Based on our data, for optimal or maximum yield, growers should be planting somewhere
between a 2.6 and 2.9 maturity group.
However, I also wanted to warn growers and impress upon them that that is just for maximum
yield.
I would not encourage any grower to go out to plant 2,000 to 4,000 of a soybean and expect
to get them harvested in a timely manner, given the fall climate that we often deal
with in the state of Wisconsin.
What I also want to remind growers is that we have a very broad shoulder in terms of
what that maturity group range is for yield.
If you look back into our 2014 soybean variety test, the starred varieties range anywhere
from a 1.9 to 2.8 maturity group.
So again, what that tells us is that though our maximum maturity group range for yield
is 2.6-2.9, growers can select varieties if they use a mechanism like our soybean variety
trial book, all the way down to a 1.9 and still get the same yields.
So, I’m really strongly encouraging growers to go into the system, go into our variety
trial book, pick about 20 percent of their land based acres, put out an early 1.9, 40-60
percent of their acres they can go with a 2.3-2.5 maturity group, and then maybe another
20-30 percent of their acres, they can go to a 2.6-2.8.
What that allows growers to really do is diversify their genetic pool across their land base
area, and also allows them to kind of deal with some of the environmental characteristics
based on early or late season rains, and really trying to capture some of that variability
we see in the environment–to really overall maximize yield over their entire production
system.
I want to switch quickly into soil test phosphorus interpretation categories.
I know Dr. Lebowski already covered this in her section, but I would like to remind people
that in her publication, A2809, Nutrient Application Guidelines for Field, Vegetable, and Fruit
Crops in Wisconsin, what the optimal soil test range is for soybean is loamy and sandy
soil.
So that would be in loamy sand, somewhere between 16-20 parts per million, and for sand,
23-32.
Similarly, on the potassium side, we’re look at a 101-130 on loamy, and 66-90 on sand.
So again, I just want to remind growers to be able to utilize this research and understand
where this optimal soil test range is, and make sure you manage your soybean production
systems accordingly, to be able to take advantage of these soybean tests and I recommend that
you take regular soil test sampling in order to make sure we’re not limiting our soybean
production system by limiting the amount of nutrients we’re putting out across our land
based area.
With that I like to remind growers that if they have any further questions, please go
to my webpage: www.coolbean.info.
You can follow me on twitter @baderbean on Twitter, or go to my blog: thesoyreport.blogspot.com