June 18, 2025 • 9 mins
Precision agriculture focuses on treating different parts of a field according to their unique yield potential instead of applying the same approach everywhere. Variable rate applications start with establishing realistic yield goals for different areas within a field based on their consistent performance patterns.
In this episode, Sarah and Jodi discuss:
• Using historical yield data to determine which areas consistently yield higher or lower
• Combining yield history with grid soil sampling data to create targeted fertilizer applications
• Assigning variable rate yield goals by zone when managing variability
• Being realistic about low-yield areas that consistently underperform
• Recognizing how nutrients accumulate in low-yield areas while being depleted in high-production zones
• Creating variable rate maps even with just composite soil samples by setting different yield goals
• Understanding precision agriculture is primarily about efficiency, not just yield maximization
• Managing costs by reducing inputs where appropriate while giving high-producing areas what they need
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Transcript
Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
Jodi (00:00):
And now it's time for a tiny bite of knowledge.
Sarah (00:13):
Jodi, let's make precision agriculture easy for
everybody out there.
Okay, when you're out by apothole, you know the area
that's super salty and likedrowns out and salts out like
all the time.
Does that yield the same aslike further away from the
pothole, where the ground isreally good?
Nope, very different.
(00:35):
Why would you treat them thesame?
That's precision agriculture ina nutshell, right there, right,
absolutely.
On today's Tiny Bytes, we'retalking about yield goals.
Jodi (00:47):
So, Sarah, fantastic point .
When you're thinking aboutvariable rate, anything, any
inputs, what's typically thefirst thing you think about?
Sarah (00:59):
It's always the yield goal across the landscape.
The yield goal across thelandscape it's always asking the
farmer what parts of the fieldyield the best, which parts of
the field yield the worst andwhy.
Help me understand and thenassigning the correct yield
goals in those spots.
Fields are never the sameacross the landscape.
(01:21):
It is not normal for us to finda field where the yield monitor
never changes as you driveacross the field.
There's a lot of differentreasons why that could be, but
generally speaking, we're alwaysgoing to find that yields will
be different in different partsof the field, and so I'm always
trying to think about settingrealistic yield goals for the
(01:45):
different areas of the field.
Jodi (01:47):
So realistic yield goals.
How do you typically thinkabout that and come up with the
yield goals that you use tocreate your variable rate maps?
Sarah (01:58):
Generally speaking, there's a few different ways
that we can think about this.
What I really like to do iswork with historical yield data
that has been well calibrated,might I add, and combine
multiple years worth of historyby the crop to find out what
areas consistently yield greater, what areas consistently yield
lower.
Based on that, if we've gotthat yield gold potential with
(02:23):
that combined yield history init, I will use those data
against the grid soil samplingdata to help us understand what
needs to be put out there forfertilizer, based on that
interaction between thatvariable yield goal and the grid
soil sampling results that arecoming back.
Further, if it's a zone field,if we're managing our
(02:45):
variability with zones, we'llassign variable rate yield goals
by the zone, so a zone can haveits own yield potential and
this makes total sense.
You know let's think about corn, for example you might have
zones that are only going toproduce 60 or 80 bushels.
If it's a super droughtyhilltop or if it's a really
(03:08):
low-lying area by a potholethat's got a lot of salt issues
in that area, you might not havethat great of yield potential.
But in that same field, in thevery productive areas, you might
have a yield potential of 220to 250 bushels and yes, I've
seen that kind of variabilitybefore.
(03:29):
Oftentimes I end up gettingconcerns from farmers where
they're concerned that ifthey're setting that 80 bushel
yield goal for that low, thatit's too low and that they might
be restricting the yieldpotential in that area.
Well, if you take a look atyour yield data over history for
the multiple years going backand you see that you are never
really getting above that area,that 80 bushels, why would you
(03:54):
fertilize for anything more?
Let's be realistic.
But at the same time, if theaverage yield goal for that
whole field has been 180, theaverage yield goal for that
whole field has been 180.
That area out there where youknow you can get 250 might just
not be getting what it reallyneeds.
Interestingly enough, oftentimeswhen we start doing soil
(04:15):
sampling from a precisionagriculture standpoint, we can
actually see some of thishappening too.
So oftentimes when we first setup a field in zones and it goes
out and gets zone soil sampledfor the first time, we will see
large amounts of the non-mobilenutrients, like potassium and
phosphorus, accumulated intothose areas with low yield
(04:37):
potentials, whereas when you goup to the really high producing
areas where all those big yieldscome off of.
A lot of times we will seelower non-mobile nutrient
content, like phosphorus andpotassium in those areas because
it's all been mined out.
You've gotten those big yields.
Now you're mining out thosenutrients out of that area.
Jodi (04:58):
So that makes a lot of sense.
So like, say, if you've beenapplying a flat rate of a
fertilizer like MAP or 1152,which contains phosphorus, and
you've been just applying it asa flat rate across the whole
field In those areas that havethe lower yield potential, like
next to a salty spot that justdoesn't grow much if you soil
sample that spot compared to,like, your high yielding area,
(05:21):
you're going to find that thearea that doesn't have a whole
lot of crop hasn't taken muchphosphorus up and you've got a
high level of phosphorus there,whereas you go to the areas that
have that higher yieldpotential and don't have much
phosphorus there because that'sall been mined out.
It just makes sense when we havethese differences that we're
going to have different levelsof available fertilizer once we
(05:41):
go and start soil sampling theseareas, so that once we do have
those results back, we can goback and in the future tailor
our variable rate fertilizermaps so that we're only applying
what we need in those areasversus what we don't, making
sure that we're not just flatrating across the whole field
because we've got high spots,we've got low spots, we've got
(06:03):
high yield potential and lowyield potential.
Every part of the field doesn'tneed to be treated the same
when it comes to phosphorusfertilizer.
Sarah (06:10):
Exactly, you nailed it on the head.
Jodi (06:13):
So Sarah say, if I'm somebody that only does
composite soil sampling and Ihave that result from last year
and I want to do variable rate,is there something I can do to
make a variable rate map for thenext year?
Sarah (06:26):
Yes, as a matter of fact, oftentimes when we are working
with a brand new client, theycome to us and the only thing
they have for soil sampling datais a composite sample, and so
with that, we have to figure outa way to do variable rate
application, and we accomplishthat with variable rate yield
goals by design.
A composite soil sample shouldtell us what the average soil
(06:49):
sample value is across the field.
Okay, so when we start havingconversations with farmers about
what is the real yieldpotential in your low producing
areas versus your high producingareas, we can use that average
value.
It's not going to be exact bythe zone or by the grid because
(07:09):
we don't have that data, but atleast it's a guide that we can
go on.
That'll give us an idea andthen we can variable rate that
based on what the production isthat we're going on.
That'll give us an idea andthen we can variable rate that
based on what the production isthat we're going to remove from
the field.
It can still help us manage ourcost and for the farmers out
there that get concerned aboutthe fact that maybe that red
area is only producing 60 or 80bushels of corn in that area
(07:33):
I've worked with farmers in thatscenario and they get really
concerned that they're going tolimit their yield potential in
that area.
And the truth is, if that isreally what you're producing, be
realistic in that and assignthat for that yield goal.
The purpose of precisionagriculture is not necessarily
to increase your yields.
(07:54):
It's to be efficient in yourproduction.
That means in those areas withthe low producing spots you're
probably going to reduce theamount of inputs that you put in
there.
But likewise in those higherproducing areas you might take a
look at some of thosefertilizer rates and go, whew,
that's a lot higher than Ithought.
(08:14):
So it's interesting because thepurpose is to be efficient with
our inputs.
Manage the cost where it makessense to manage the cost.
Give those good producing areaswhat they need to produce the
good yields.
It all starts with realisticyield goals and variable rate
yield goals across the field.
Jodi (08:35):
I think this conversation yielded a lot of great
information.
Thank you so much, Sarah.
I agree, Jodi.
Thank you so much.
Tune in next time for a tinybite of knowledge from GK
Technology, where we have a mapand an app for that.
And now it's time for a tiny bite of knowledge.
Sarah (00:13):
Jodi, let's make precision agriculture easy for
everybody out there.
Okay, when you're out by apothole, you know the area
that's super salty and likedrowns out and salts out like
all the time.
Does that yield the same aslike further away from the
pothole, where the ground isreally good?
Nope, very different.
(00:35):
Why would you treat them thesame?
That's precision agriculture ina nutshell, right there, right,
absolutely.
On today's Tiny Bytes, we'retalking about yield goals.
Jodi (00:47):
So, Sarah, fantastic point .
When you're thinking aboutvariable rate, anything, any
inputs, what's typically thefirst thing you think about?
Sarah (00:59):
It's always the yield goal across the landscape.
The yield goal across thelandscape it's always asking the
farmer what parts of the fieldyield the best, which parts of
the field yield the worst andwhy.
Help me understand and thenassigning the correct yield
goals in those spots.
Fields are never the sameacross the landscape.
(01:21):
It is not normal for us to finda field where the yield monitor
never changes as you driveacross the field.
There's a lot of differentreasons why that could be, but
generally speaking, we're alwaysgoing to find that yields will
be different in different partsof the field, and so I'm always
trying to think about settingrealistic yield goals for the
(01:45):
different areas of the field.
Jodi (01:47):
So realistic yield goals.
How do you typically thinkabout that and come up with the
yield goals that you use tocreate your variable rate maps?
Sarah (01:58):
Generally speaking, there's a few different ways
that we can think about this.
What I really like to do iswork with historical yield data
that has been well calibrated,might I add, and combine
multiple years worth of historyby the crop to find out what
areas consistently yield greater, what areas consistently yield
lower.
Based on that, if we've gotthat yield gold potential with
(02:23):
that combined yield history init, I will use those data
against the grid soil samplingdata to help us understand what
needs to be put out there forfertilizer, based on that
interaction between thatvariable yield goal and the grid
soil sampling results that arecoming back.
Further, if it's a zone field,if we're managing our
(02:45):
variability with zones, we'llassign variable rate yield goals
by the zone, so a zone can haveits own yield potential and
this makes total sense.
You know let's think about corn, for example you might have
zones that are only going toproduce 60 or 80 bushels.
If it's a super droughtyhilltop or if it's a really
(03:08):
low-lying area by a potholethat's got a lot of salt issues
in that area, you might not havethat great of yield potential.
But in that same field, in thevery productive areas, you might
have a yield potential of 220to 250 bushels and yes, I've
seen that kind of variabilitybefore.
(03:29):
Oftentimes I end up gettingconcerns from farmers where
they're concerned that ifthey're setting that 80 bushel
yield goal for that low, thatit's too low and that they might
be restricting the yieldpotential in that area.
Well, if you take a look atyour yield data over history for
the multiple years going backand you see that you are never
really getting above that area,that 80 bushels, why would you
(03:54):
fertilize for anything more?
Let's be realistic.
But at the same time, if theaverage yield goal for that
whole field has been 180, theaverage yield goal for that
whole field has been 180.
That area out there where youknow you can get 250 might just
not be getting what it reallyneeds.
Interestingly enough, oftentimeswhen we start doing soil
(04:15):
sampling from a precisionagriculture standpoint, we can
actually see some of thishappening too.
So oftentimes when we first setup a field in zones and it goes
out and gets zone soil sampledfor the first time, we will see
large amounts of the non-mobilenutrients, like potassium and
phosphorus, accumulated intothose areas with low yield
(04:37):
potentials, whereas when you goup to the really high producing
areas where all those big yieldscome off of.
A lot of times we will seelower non-mobile nutrient
content, like phosphorus andpotassium in those areas because
it's all been mined out.
You've gotten those big yields.
Now you're mining out thosenutrients out of that area.
Jodi (04:58):
So that makes a lot of sense.
So like, say, if you've beenapplying a flat rate of a
fertilizer like MAP or 1152,which contains phosphorus, and
you've been just applying it asa flat rate across the whole
field In those areas that havethe lower yield potential, like
next to a salty spot that justdoesn't grow much if you soil
sample that spot compared to,like, your high yielding area,
(05:21):
you're going to find that thearea that doesn't have a whole
lot of crop hasn't taken muchphosphorus up and you've got a
high level of phosphorus there,whereas you go to the areas that
have that higher yieldpotential and don't have much
phosphorus there because that'sall been mined out.
It just makes sense when we havethese differences that we're
going to have different levelsof available fertilizer once we
(05:41):
go and start soil sampling theseareas, so that once we do have
those results back, we can goback and in the future tailor
our variable rate fertilizermaps so that we're only applying
what we need in those areasversus what we don't, making
sure that we're not just flatrating across the whole field
because we've got high spots,we've got low spots, we've got
(06:03):
high yield potential and lowyield potential.
Every part of the field doesn'tneed to be treated the same
when it comes to phosphorusfertilizer.
Sarah (06:10):
Exactly, you nailed it on the head.
Jodi (06:13):
So Sarah say, if I'm somebody that only does
composite soil sampling and Ihave that result from last year
and I want to do variable rate,is there something I can do to
make a variable rate map for thenext year?
Sarah (06:26):
Yes, as a matter of fact, oftentimes when we are working
with a brand new client, theycome to us and the only thing
they have for soil sampling datais a composite sample, and so
with that, we have to figure outa way to do variable rate
application, and we accomplishthat with variable rate yield
goals by design.
A composite soil sample shouldtell us what the average soil
(06:49):
sample value is across the field.
Okay, so when we start havingconversations with farmers about
what is the real yieldpotential in your low producing
areas versus your high producingareas, we can use that average
value.
It's not going to be exact bythe zone or by the grid because
(07:09):
we don't have that data, but atleast it's a guide that we can
go on.
That'll give us an idea andthen we can variable rate that
based on what the production isthat we're going on.
That'll give us an idea andthen we can variable rate that
based on what the production isthat we're going to remove from
the field.
It can still help us manage ourcost and for the farmers out
there that get concerned aboutthe fact that maybe that red
area is only producing 60 or 80bushels of corn in that area
(07:33):
I've worked with farmers in thatscenario and they get really
concerned that they're going tolimit their yield potential in
that area.
And the truth is, if that isreally what you're producing, be
realistic in that and assignthat for that yield goal.
The purpose of precisionagriculture is not necessarily
to increase your yields.
(07:54):
It's to be efficient in yourproduction.
That means in those areas withthe low producing spots you're
probably going to reduce theamount of inputs that you put in
there.
But likewise in those higherproducing areas you might take a
look at some of thosefertilizer rates and go, whew,
that's a lot higher than Ithought.
(08:14):
So it's interesting because thepurpose is to be efficient with
our inputs.
Manage the cost where it makessense to manage the cost.
Give those good producing areaswhat they need to produce the
good yields.
It all starts with realisticyield goals and variable rate
yield goals across the field.
Jodi (08:35):
I think this conversation yielded a lot of great
information.
Thank you so much, Sarah.
I agree, Jodi.
Thank you so much.
Tune in next time for a tinybite of knowledge from GK
Technology, where we have a mapand an app for that.
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