(bright music)
-: Hi, I'm Taro Mieno.
I'm an assistant professor at the agriculture economics
at the university of Nebraska Lincoln.
Today I'm going to talk about
how we may be able to use our on farm
randomized seed rate experiments to identify
optimal seed rate decisions
viable rate seed rate decision.
Okay, so here is the map of target seed rates
randomized target seed rates.
It ranges from 60 to 140, as you can see,
the seed rates are randomized across the field.
right here is the resulting yield
soybean yield.
So as you can see,
the upper half of the field is high yielding,
and relatively speaking
the lower part of the field is less,
is not as as productive as the upper part of the field.
So the soybean yield ranges from 20 to 70.
And the most productive part is again is at the upper half,
and you can see that 70 to 60 bushels per acre
on the upper part of the field.
Okay, here is the target seed rate
and soybean yield side by side
it's a little bit hard to get anything away
from just from just looking at two maps here, but
one thing you can see here is that
the upper right corner,
even though low seed rates
were applied on the upper right part of the field,
you can still see that yield is very high.
So you would imagine that the yield response
in that part is not very high.
Okay, so after collecting target seed rates
and the soybean yield data across the field,
we can do some statistical analysis
and we can identify how yield is responding
to seed rate across the field.
Okay, so this is yield response
to seed rate bushels per acre, per a thousand seeds
so for example, 0.4 means that if you increase
seed rate by 1000 seeds per acre,
then you would have 0.4 bushel per acre boost in your yield.
So you can see that middle part
of the field is very responsive to seed rate
but upper lower left corner and upper right corner
you can see that soybean yield is not responding
to seed rate very much.
Okay so here is the map.
Well, here are the maps of soybean yield
and yield response to the seed rates side by side.
One thing you can take away from these maps,
that it's not necessarily
that the high yielding parts are responsive to seed rate.
And let's try to understand why we see differential
yield responses to seed rates across the field.
So here is the map of yield response
to seed rate and soil type.
By comparing these two maps,
there's no,
it doesn't seem to be any significant correlation
or relationship between soil type and yield response.
So, we are inconclusive about
the impact of soil type on yield response to to seed rate.
Here is the map of yield response to seed rate
and elevation, so again,
it's hard to see what is causing
differential yield response to seed rate.
There does not seem to be any significant correlation
between elevation and yield response to seed rate.
So in fact, we were not able to find
out exactly why we see differential yield responses
to seed rate in this field.
Okay,
so after identifying differential responses
or responses to seed rate
based on solving price of $9
per bushel and seed price
cost of $0.35 per 1000 seeds
we can identify the economically
site-specific economically optimal seed rate.
And here is the map of economically optimal seed rates.
It ranges from 60 to 140,
and the lower bottom part
and upper right corner,
you can see the optimal seed rate
is 60,000 seeds per acre,
but for the most part of the field 140K seed rate,
the economically optimal seed rates.
okay, let's do economic analysis on this field.
So the grower who would have chosen 120K seeds per acre,
if it were not for this week's experiment,
and we have got to compare
that decision the grower would have made
to the economically optimal seed rates we identified
which range from 60 to 140.
And we assume that soybean price is $9 per bushel
and seed price is $0.35 per 1000 seeds
Okay,
Then we put those.
If the grower doesn't have viable rate application system,
then that would cost $5 per acre.
Okay, so the site-specific optimal rates
would have made $15 per acre more
or about $10 per acre more,
if you use viable rate application services.
Okay. So the, this economic gain comes from two factors.
The first one is to save seed costs
in the area where yield does not respond
to an increase in the seed rate.
That's the lower bottom, lower left corner
of the field and the upper right corner of the field.
The farmer would have the grower would have applied 120K
per acre, but the economically optimal rate
is actually 60,000 seeds per acre.
And the second factor is that
it will be economically optimal to plant more seeds
in most parts of the field.
the economically optimal rate was 140,000 seeds
per acre for the most parts of the field,
but the grower would have chosen 120,000 seeds per acre.
And the grower might want to try even higher rates
and other experiments because 140,000 seeds
per acre was the maximum rate that we tried.
And we identified that rate as the economical optimal.
So it may be that even higher rate could make
the grower more money
On caveats.
So this is only one year of data.
So we didn't
we were not able to take into account weather uncertainty.
So if we run another experiment in a different year
we may have, we may have had a different result.
And we were not able to identify the underlying causes
of the differential responses to seed rates.
So it may be a good idea to talk
with a specialist, your consultant
or your consultant
to understand why some parts of
the fields are more responsive
to seed rates than other parts.
And that may be able to help you to
identify the strategies to improve your yield.
Okay, so take home points.
On farm randomized experiments of seed rates
can help growers better understand how yield responds
to seed rate sites-specifically.
And it will also help you to find out whether growers
are over applying or under applying seeds on average.
Okay,
and further it will let you find
the site-specific economically optimal seed rates
and running experiment on farm experiments
like this, may benefit you
by a sizable margin.