S4E7: Back to Basics: Soil Fertility Testing

Recorded: 11/05/25

In our back to basics series, our hosts discuss the foundational agronomic principles that will improve crop management on your farm. In this episode, Ryan, Justin, and Dwane discuss the importance of soil fertility testing, how to take a soil test, and interpreting a soil test.  

Hosts: Ryan Spelman, Justin Brackenrich, and Dwane Miller

Links:
Soil Fertility Testing
Interpreting Your Soil Test Reports
Soil Sampling

Sign up for our newsletter, Field Crop News, and follow us on Facebook!

Transcript

Ryan Spelman (00:18)
Welcome to another episode of the Agronomy Highlights podcast. I'm your host, Ryan Spellman, and I'm joined here with not one, but two of my lovely co-hosts. We have both Justin Brackenrich and Dwayne Miller in the house. So why don't you guys say hi for me

Justin Brackenrich (00:35)
Hi everyone Yes, it is a little bit different for us today having all of us here But thanks for tuning in and joining us Dwayne you with us still

Dwane Miller (00:43)
Yes, hey everybody. Sorry if my voice is a little bit off. I'm battling a little bit of a cold, but bear with me. great to be here today and we're recording this in early November. Sun's shining right now and crops are coming off. We're progressing pretty good and as far as taking the crops off, looking for some good weather to keep this momentum going.

Ryan Spelman (01:05)
There you go. So there's our roll call. So you know we're all here. One of the things, one of the reasons we're all here today is to talk about some back to basics. As Dwayne mentioned, we're in the fall right now. Harvest is well underway, if not, you know, nearing completion in some of our areas. So it's a good time to kind of sit down and

talk about some basics of soil testing. This is a great time to get in the field if you can and do some soil testing. We'll talk a little bit about that later. Justin, why don't you maybe share a little bit about what these back to basics sessions are and what we're gonna do here today.

Justin Brackenrich (01:41)
Yeah, sure. So we kind of came up with this idea, right? We've been doing a lot of these podcasts and kind of transitioning a little to new ideas and new things. And so this idea came up is a lot of time we spend talking about what's new in wheat or biologics or nutrients or amendments in soils. But sometimes we really forget like the basic fundamental good agronomic practices, right? I go out and I visit with farmers or I have phone calls and you say like, what was the last time you live? Well,

When was the last time you applied nutrients? And these are the things that are going to help us control a lot of weeds, produce a lot of good crops. And so we decided, let's just step back. We're going to run through this series. Occasionally, you're going to see one pop up, and it's going to be back to basics. We plan to do soil testing, Lyme and magnesium, talking a little bit more about nitrogen management, phosphorus and potassium management. Then we think some ideas on herbicides or things, too. Just kind of giving us all.

a good foundation, a good starting point to take up on some of these bigger, more complex conversations. Hope I summarized that well enough.

Ryan Spelman (02:45)
Yeah, definitely. mean, that's exactly what we're trying to do here. think, like you said, probably in a lot of our episodes, we cover these higher level topics and really a lot of them start with the basics, right? So we need to make sure we're doing our basics. I think one of the episodes that was driven home was, well, two episodes. Our last episode when we talked about wheat fertility, mean, everything came back to...

do your soil test, get the basics right, and then try these things. Our episode on biologicals with Connor Seibel, it was all about, these are value added things, but if you don't have the basic agronomic concepts down, it's not worth your time, right? So hopefully this can be a tool for you to use to kind of brush up on some of these topics. All right, so let's just jump straight into it. So we have some questions here to guide this conversation, but we'll just kind of...

pitch them around and see where we go with this. one of the things I kind of wanted to start this conversation with is talking about like why soil tests in the first place and what's the importance of soil testing,

Dwane Miller (03:51)
Well, I think, Ryan, this is really important that we started the back to basics with this one, because this episode on soil testing, because I think this is the foundation where we get everything started from. And to your point, you just mentioned two episodes that we previously stressed hard on this. And it basically lies the foundation for everything we're going to do.

You know, we farm at home too, and it's so easy for us to just get locked into, well, you know, we throw down this much potash on the hay ground, or we do this, we do that on this crop, but if we really want to be in tune with what's going on and have an understanding and capitalize on the investment we're going to make in planting that crop, I think it's just so important to

get that fertility in line and understand our baselines of where we stand with pH and nutrient levels in the soil. Because it's going to affect a lot of what we're going to do and the potential for a good crop, potential for fertilizer availability.

Potential for herbicide activity a lot of that is going to be based on those soil test levels

Justin Brackenrich (05:19)
So one of my bigger pet peeves is and maybe that's not right maybe maybe it's not a pet peeve Maybe it's just like one of my pull your hair out kind of moments that I experience a lot is Someone calls and they'll say hey I how much boron or sulfur should I be putting out on this corn crop? To make this the best crop it can be and I say, okay When was the last time you took a soil test and what's your soil potassium and they say ⁓ geez it's probably been, you know, five seven years and

I can pull it up and look and they say, our potassium was 70 parts per million. But seriously, how much boron do I need to add? Right. And like, I think that's where we start to slip on some of this is there is so much information thrown at us about what's new in micronutrients and biologics and foliars, but we're forgetting our magnesium, our phosphorus, our potassium, our pH.

And so many times that I'm working in forages, right? People say, what should I reseed with or what nitrogen rate should I use? I think we start with this soil test, right? Let's get a soil test. Let's get some phosphorus and potassium out there. And it's amazing how some of these species just show up and start to express, right? The orchard grass that you said wasn't there. Here it comes once we get some phosphorus, right? The red clover start to show up once we get some of this stuff out there. And I think that's that like real world take home.

What is soil testing done for me lately is when you're not doing it, you don't know and You know, I'm kind of on this soapbox This is this is a big thing for me if you woke up one day and your grasses or your corn Because you weren't testing him went from 200 bushel to 150 bushel You you'd perk up and you'd say what the heck happened here, but because this isn't a bank account This is like a slow draining effect

It takes 10 years before people start to notice this stuff sometimes, right? And they'll say, well, dad did something with it 15 years ago and I noticed it's just not doing anything anymore, right? We just, kind of have this hidden hunger and this slow depletion that once we can correct that, it's amazing how this playbook opens for what we can manage in our crops. Sorry, I don't mean to sound preachy, but this is a really important topic that we overlook all the time.

Ryan Spelman (07:29)
Sure, yeah, and to your point, Justin, I think what you said, we're working in reality, right? As much as we think we can predict what nature does and what biology does, at the end of the day, if we're not checking ourselves along the way, there's no way for us to see if what we're doing is actually helping the crop respond, the soil respond, or it's not. And to your example with the...

pasture situation. actually had a case where we had a farm, I had a farmer that had a, he had a lot of weed issues in a pasture that he inherited. It was really patchy. He wasn't seeing some of those desirable species. And so immediately my head went to, okay, this is probably a fertility issue first. And then we can talk about whether it needs a reseed. And then he took the soil test and it turned out a lot of his, ⁓ everything was at an optimum place in the nutrients. ⁓

and his pH was okay. So in that case, he actually did have good fertility and then we could make the decision, okay, this is a time to reseed, right? So it's just that piece of evidence that you can use to make a better decision and to track your decisions over time. I think it's just a really important check-in and way to assess what you're doing and how it affects reality. So we'll jump into this.

what you actually get out of a soil test. for this conversation, I think for the most part, we'll focus on Penn State soil testing. What's important to know is there's labs. I know we have viewers all over the country. A lot of universities, land-grant universities have their own soil testing labs, as well as industry. know, we're not saying ours is the best or anything. We just know the Penn State methods. So we're going to focus on those.

one thing to lean on and Penn State's is in this program is that it's certified by the North American Proficiency Testing, the NAPT service. This is a program of the Soil Science Society of America, you know, the same program that CCAs fall under. And basically in order to be a part of this program, it,

kind of ensures that your results, your soil testing results are fairly accurate. there's a certification process that I don't really know much about, but then beyond that, labs in the program can send samples to other labs and have to at certain frequencies to make sure that they're getting similar results to another lab and there's not too much bias. So that's just kind of one way to make sure you're in.

getting a soil test that's accurate and reliable.

Justin Brackenrich (10:04)
think a lot of times we do these meetings or we talk about soil testing. Maybe Penn State wouldn't like me saying this, but the biggest thing I think that you can do for soil testing is stick with one lab, right? We're gonna go through the steps of depth and timing and all of those kinds of things. But I think, like Ryan said, using the NAPT program to make sure they're an accredited lab and then picking one and sticking with it, right? Because then we're not gonna get different extractable nutrients. We're not gonna get different ratios.

Um, you know, if, Penn State goes a couple of years ago, we went from $9 a sample to $10 a sample. Well, don't let that $1 or something bother you and make you start looking for another lab. Pick a good lab, run with that one. That's a good way that we can catalog these things over the years and see any type of change that might happen. Good or bad, right? We sometimes see bad change with some of our farming practices.

Ryan Spelman (10:55)
Yeah, definitely. Yeah, because no matter what we try, every lab is going to have their own bias. They have their own equipment, their own chemicals. So it is really important to stick with that one so that you're getting that same bias, you know, and you can can really ensure that that you're you're responding based on the same test. So we'll talk a little bit about what a basic test gets you here. So you're going to find your.

P's in your case, so phosphorus, potassium, pH, and magnesium. That's kind of your macronutrients, the most important ones that you're gonna get with the standard soil test. So maybe one of you guys can answer the question, why not nitrogen?

Dwane Miller (11:33)
So nitrogen recommendations are going to be varied. It's going to be specific to the crop that you're indicating that you're going to be planting. nitrogen isn't, well, let me back up. Nitrogen is not readily measured in the soil accurately at any one snapshot in time. So if you take a soil sample, say, today,

right after you put some nitrogen down, that nitrogen recommendation or the nitrogen reading might be there in the short term. But if we get a rain event, it's applied on the soil surface and we get some volatilization, that nitrogen won't be around in the long term. So measuring nitrogen over a course of time is difficult to do. So the nitrogen recommendations when you

analyze your, put a soil test report in, is going to be based on the crop that you're going to be using in that scenario and then also your yield goal. So it's driven by two things basically is the crop that you're planting and the yield that you're looking to get out of that crop.

Justin Brackenrich (12:41)
And I think if you're interested in that, we have an episode and we've done a lot of work discussing things like the pre-side dress nitrogen test. And there are total nitrogen tests and stuff in your soils that you can do. They're just a different test than what you would get for kind of your standard routine sample.

Ryan Spelman (12:59)
Yeah, great. think that's it's the reason I brought it up first is because that's one of the first questions I get about soil tests from from a lot of folks when they're getting into this is like, what about my nitrogen? Right. And that really is based on the crop that you're growing at the time in the the plant available form, because it is so dynamic. Right. But your phosphorus, your potassium, your magnesium.

these are all less dynamic and we have some level of predictability how that implementing that fertilizer will actually affect the crop that's there and the soil that's there. So Dwayne hit on another important thing. What we're doing when we're looking at our soil test results, we're looking at getting soil levels of these nutrients or of your pH to an optimum level, right? And that's based on

building the levels up over time. So maybe if you're doing the soil test over the course of three years, we're building that up to a place where it's optimum. And then we might need to step down our fertility based on our test in the future so that we keep it in that optimum range. So that's kind of a little bit of the basics of why we're doing this and how we're keeping these levels at optimum. So maybe we'll jump into how we take a soil test.

So any advice from you guys on, I want to take a soil test and I want to get a, where do I find a soil test and how do I go about taking one?

Dwane Miller (14:26)
I'll start a little bit, Ryan, as far as where do we get a soil test kit? You can purchase a soil test kit from any of the Penn State Extension offices. They sell them there. Like Justin indicated before, a Penn State soil test kit is $10 per sample. You don't have to actually.

drive to the Penn State Extension Office to grab those soil test kits if you don't want to. We'll put in the show notes the address to our soil testing lab out at Penn State University. And in there are the instructions for taking a soil sample. And you can also print out a standard soil test form, fill that out, and use your own Ziploc bag to

to do the sample so you'd actually, you don't have to drive to the office to grab a physical sample kit. You can do those on your own. So that's where to get the soil test kit. I'll stop there and bring it up to somebody else.

Justin Brackenrich (15:27)
Sure.

I can do how, right? I think, you know, this is one of those big kind of it depend questions for us in extension, right? And you never know how we like those. I, we talked a little bit about picking the same lab. The other really major part of soil testing is consistent depth, right? And if you think about what happens if we're thinking about something like corn or soybeans where we might be sampling six to eight inches.

on that sample, right? If we come in and we take one at six or eight inches, we're likely starting to hit the top of that subsoil where our pH may be a little lower than perhaps the top two inches. And our potassium and our stratification of nutrients will be a little different if we're talking about no-till. And so if we're, you know, kind of just trudging along and we poke one at eight inches and then we poke the next one at three inches and the next one at four inches, what happens is we don't get kind of this consistent representation of that top six to eight inches.

And so what we think about is like we have to have this spatial representation, right? This can be something like we go out and we zigzag around and we avoid, we avoid wet spots. We avoid ⁓ overly dry spots. avoid animals where, or excuse me, areas where animals might congregate, fences, trees, you know, any of these things that could skew our data. So it's not just kind of the surface spatial nature, but we also have a good representation of the depth, right? How do we take

⁓ One or ten or twenty acres whatever it is six or eight inches deep poke enough holes in the ground to figure out what that looks like consistently and and so I think it'd be a good one for maybe a different topic but There are a lot of different ways that we can guide ourselves to this we can look at it from a management aspect, right? Dwayne's got one cornfield. He goes out pokes a bunch of holes that whole cornfields treated the same way

He can look at it on like a soil type or a topographical type management where he knows there's a change in the soils. He knows this part's lower and this part's higher and so he samples those differently. We can get into grid sampling, right? And there are all of these different ways that you can grid sample. You can do it kind of from one prism and take a bunch around it. You can do one prism, like one kind of point every so often. Soil sampling can be very, very complicated.

And my advice to most people when they do that is sample to the level of management in which you can work at, right? If you know that you can't kind of get in there's a very finite level, you know that you're not going to split apply anything. You know that you're not going to adjust tonnages. What you're doing is creating more work and more effort for yourself that you're going to frustrate yourself. Start very large. And then as you see these managements gets better, then we start talk about other ways to take these samples.

Ryan Spelman (18:08)
Sure, and I think that's a great point is defining your management zone. This is all based on a zone. If we're looking at, we doing this by field? Well, that depends. Are you rotating by field? The approach that I usually see people doing is, I have this one field that gets rotated, corn, soybean, and the next field over it's rotated, soybean, corn, then break it up that way.

It's all based on, like you said, what your management practices are. And usually when I talk how to take a soil test with folks, I usually recommend in that management zone taking 15 to 20 samples. I don't know, is that the number that you guys usually land on?

Dwane Miller (18:52)
I usually go for make sure you try to get at least a dozen.

Justin Brackenrich (18:56)
Think I think there's this thing where you tell someone hey get 20 samples and they go out and they're like, yeah This isn't gonna be a big deal when he's a lot to about six and they're like, my gosh Especially if they don't have a soil probe, right if you're talking to someone with a shovel You know and like I I say like I know this can be challenging. So don't get frustrated Take your samples be consistent, but I agree if you're getting a dozen. I mean something's better than nothing

Ryan Spelman (19:21)
Yeah, yeah. Okay, cool. It's the scientific mind that makes me want to say 15 to 20, but I think a dozen is a good amount.

Dwane Miller (19:23)
I

I try to stress to folks, I believe when we did a tour of the soil test lab up there at Penn State one time, know, the Penn State kits say, all right, you want to fill the bag to a certain line, and that's about a cup worth of soil. So you're trying to aggregate whatever that is, a 10 acre field, ⁓ 20 acres into that cup. But out of that cup, I believe they use about a teaspoon.

when they're actually testing that soil. So I try to indicate the importance of garbage in, garbage out. Like Justin just mentioned, if you're varying your depth, if you get three or four cores and say, you know what, the heck with it. I throw the towel in. You're only gonna get a result that's as good as what you're putting into it.

Justin Brackenrich (20:22)
And I think for perspective, right? Like what's a half a cup of soil weigh? four or five, six ounces, right? And so when we think about that six or at six inch, seven, eight inch depth, we're thinking about 2 million pounds of soil per acre that now Dwayne says we need a cup of it. So if we've got a 10 acres, 2 million pounds an acre, we've got 20 million pounds of soil that we're trying to figure out how to get these samples pulled out.

put them in a bucket, stir them up, make this composite or aggregate sample, then pull a cup of that and base our management on it, right? I mean, you're kind of fighting a losing battle. So the more the better, I think is kind of the key to take away from how many samples or how many subsamples you should be collecting.

Ryan Spelman (21:04)
Sure, yeah. okay. So, and now to get into the nitty gritty of like how you actually take these samples, that matters too, right? So like having, use soil probes and like, I think if you're gonna be taking these at any kind of frequency, as you probably should if you're managing a farm, I think that's a very worthwhile investment because it saves a lot of time over, you know, the shovel method where you put that soil probe in to that six to eight inch depth, you get a really

consistent sample, twist that probe, pull it out and then you have your core. That's a really great way to get a consistent sample. There are other methods and we'll attach those in a link as well. If you just have a shovel, you can dig like a triangular pit and then take a one inch slice along the side. as you can tell, that takes a little bit more time. So if you are doing these with frequency, invest in a soil probe or

you know, if you want to try this out, talk to your local extension agent and they might be able to set you up with one. So that's, so once you have those cores, if I'm taking 15, 20 samples, I'll usually have a bucket and I'll put all those samples in the bucket and I'll break up all those cores and mix it all together. And then I'll pull my one cup sample. And what's important there is, is if the soil is a little wet, you might want to let it dry a little bit because

when the soil gets sent to the lab, they need a dry sample. And the longer it takes them to dry it down in the lab, the longer your results will take to get back. And there are some inaccuracies that can happen if they really need to dry it down quite a lot.

Dwane Miller (22:45)
Plus you're going to be sending that through the either, well, that's right. Maybe going through the postal service or if you live close enough, you deliver it locally, but you're going to pay for water weight shipping. So you might as well let it dry out. I've done the same thing as my advice is let it sit out, dry it out overnight at least, put it on top of the wood stove the stove at night.

Not the kitchen stove, but the wood stove or something like that. gonna try out.

Justin Brackenrich (23:13)
So I was always taught, and maybe you guys have an opinion or not on this, but when you're drying them, if you're interested in organic matter, which a lot of our producers are, you don't want to put them on anything like porous to dry, right? If you don't care about organic matter, you can dry them on newspaper or a paper plate or something like that. But if you're drying for organic matter, as that stuff sits there, you start to lose some of those acids and some of those things start to come out and get absorbed into that paper product.

and that can skew that data. don't know. mean, that was any thoughts or opinions on that? that seem, I mean, it seems reasonable to me just through chemical properties.

Dwane Miller (23:48)
It does, Justin. I mean, I can tell you, I've not, that was new news to me, but it does make sense. That's right. You learn something new every day.

Justin Brackenrich (23:56)
Well, you heard it here first.

Ryan Spelman (24:00)
There you go, my job's done for the day because I learned something new as well. So we'll go and-

Justin Brackenrich (24:04)
And it could

be totally wrong, right? I mean, that's crazy part about this. You learn something new, but you don't know if it was something right or something wrong, but still something new nonetheless.

Ryan Spelman (24:13)
Sure. Well, so that's a nugget of things that our listeners can go out there and do their own research and learn more about. So.

Justin Brackenrich (24:19)
So I think we've we've talked about Real-world why it matters. We've talked about where you get your kit We've talked about how you collect your sample what you need to do. You're mailing it to your lab. I Think this is another great question that did I kick around a lot is What is the best time of year that you should be doing this and with what kind of frequency?

Ryan Spelman (24:41)
Yeah, I guess.

Justin Brackenrich (24:42)
I'm do you guys have thoughts on that?

Ryan Spelman (24:44)
I do. Yeah. So I guess the best time of year, I think the fall is king, you know, of the best time of year to sample. The reason I say that is because specifically when it comes to pH, of the biggest things that's going to impact your soil and like if you can do anything to amend your soil, it's can we increase the pH of the soil? Because then it impacts the ability

of all kinds of nutrients to be accessed by the plant, right? That's why we want to get our soil to a neutral pH. anyways, liming often takes three to six months to actually act in the soil. So if you're doing like a standard rotation of corn, soybean as your cash crop, then taking a soil test in the fall enables you the ability to maybe do a late fall application of your limestone of these other fertilizers.

and have that pH be active when you go in or a little bit more active when you go in in the spring. So I think that's the best time, but really there is no wrong time with soil testing. You can do it anytime if the ground's frozen, you're not gonna be able to do it with as much success. So the fall is a good time. The spring is another great time to do it. Just know that it's gonna impact your ability to get in there.

and change the pH quickly. So I think fall first, spring second, and then any other time after that. Any other thoughts?

Dwane Miller (26:12)
No, I agree. Hey, falls. Usually the time we say to folks this. This is a great opportunity for you.

Crops are off, if crops are off, right? Makes it a little bit easier to maneuver around that field versus mid-July or something when you're trying to snake through corn rows that are up over your head. So from my standpoint, yeah, if the crops are off the ground or crops are off the field, it makes it heck of a lot easier to do soil test in row crop fields. to your point,

Ryan, as far as making anything work with liming recommendations, now is the best time to be doing that, to try to get that on the field for next year.

Justin Brackenrich (26:58)
don't know that I've had a conversation about soil testing in this way, but as we're talking about it, what I'm hearing in these common threads is just like the importance of consistency. We've said consistent lab, we've said consistent date. Dwayne mentioned about crops. One of the big things about sampling at a consistent time of year is, let's say Dwayne samples in May or April of this year.

And then three years from now, right, when his cycle comes up, he samples in the fall. Now he suffer experience the removal rate of that last year's crop. Right. And so that's one of the key benefits of fall sampling is you're past the crop harvest, you're past that removal rate. But if you go fall one year, spring the next time, now that that removal rate of that crop is starting to show up, we also see differences in like the temperature of the soil. Right. I one of the things that's really hard to chase is like sulfur and zinc problems.

because they're pretty affected by temperatures and things that can swing in the spring and fall. So, and what Ryan said, right? If someone calls and they say, hey, it's July, I've not sampled in 20 years. If you've got the momentum, get outside, right? I'm never gonna talk someone out of sampling. If this is the first time in 10 or 20 years, they've done it. There is no time like the present if you're motivated and you just don't wanna lose that.

Ryan Spelman (28:14)
Yeah, that's a great point. And I think the consistency and timing, that is important. as you're saying, we also have farm operations to run. So also find the time that makes sense in your operation. It might be different than someone else. And then stick to it. Stick to it so that you can build your recommendations over time. So I think that kind of goes into your second part of the question, ⁓ frequency.

⁓ You kind of talked about this little bit, but these tests are usually written on a three year interval. And so what that means is the lime recommendation to adjust the pH is made so that this is the amount of lime that you should make over the course of three years or, you know, all at once for that three year period. And then your fertility recommendations, your P's and K's and some nitrogen for crop removal are going to be made on a per year.

basis. So really the first you should start by using a three year rotation. So soil test every three years. Now as you kind of build up a history of soil testing, you'll start to learn what works for you, what works in your system. And as long as that system is continuing, I do see people kind of stepping back a little bit. Maybe I wait till fourth year or so.

So that's definitely an option, really you wanna, you're new to this and you're really trying to understand and study your system, three years is the best for the frequency. And you might not wanna do all your fields in one year, right? You might wanna say, okay, this is the third of my farm that I do this year. This is the third that I do the next year, know, that kind of thing.

Justin Brackenrich (29:52)
And I think that makes sense, It's workload, it's the cost of the fertilizer and the lime, it's the cost of the soil testing. I think that those systems are very, very thought out and very well established when you do a third of your acres every three years, essentially, right? I think that makes a ton of sense.

Dwane Miller (30:11)
And I think anytime there's a change in management, if you're picking up any new ground, that's one of the first things we're going to do is try to put a baseline there.

Justin Brackenrich (30:22)
And this conversation about how frequent, so I've had conversations with our lab director, John Spargo and, and John, I mean, he said, like, if you're going to put lime out, it doesn't behoove you to take a sample within 18 months. Right. Especially if you're thinking about nutrients and pH effect on those kinds of things too, is you've not seen the full effect of that lime. You really don't know where things are. So I think this idea of like yearly sampling

can almost make us chase our tails a little bit more because we're not seeing all the breakdowns of all of these things in the soil at a fast enough rate to know what they're going to do.

I think we've run through a bunch of this stuff. ⁓ You know, again, what was stress, the consistency we've talked depth, we've talked year, we've talked how often I don't know, do we want to get into the conversation of ⁓ reagents and the acids that are used to get into this? Or do we think we want to leave that for another day?

Dwane Miller (31:20)
It's above my pay grade of what, you know, what they typically, mean, I know the, okay, there's the different tests, the male, like the bray, hey, we focus at Penn State on this one. This is what is, but I, Justin, if you know.

Justin Brackenrich (31:38)
I my my 30,000 foot right and and I'm gonna kind of jump back in here again Remember, this is soil testing basics, right? This is this is back to basics. If you are like boy I'm thirsting for more information on soil test extractants Then then let us know we'd be happy to do that Again, I think this is part of that consistency like Dwayne mentioned. There are lots of different kinds Melick one and Melick three are probably the most popular that I see

There are Brays, Morgans, Olsens, you know, all of this stuff that floats around. But my advice is contacting or working with your extension agency to see what your land grant and what your extension deems to be the best extractable type reagent that you can use in your state, right? So for us in Pennsylvania, it's malec-3. And so a lot of labs are using that because that data becomes comparable, right? If you have a parts per million of 20,

and malec one versus a parts per million and malec three, the addition of fertilizer is not the same for those two numbers, right? They are not exchangeable and you can't look at fertilizer recommendations just because it's a 20 parts per million. And when we think about that, kind of specifically, Pennsylvania's recommendations are for malec three extractable nutrients. We don't have that set of data. We haven't done that research. We don't have that log that says, well, I decided to use

malec one or bray, what do I need to add? Now you have to start going to a state or a university that has that set of data and hoping it translates well to your farm and your soils in a different environment, right? I think that's kind of a 30,000 foot. I don't know. Maybe you guys have more to add or maybe that makes more questions. But I think the importance of that is talk to extension, find out what they're doing and try and stick with that. So it gives you recommendations are going to be most accurate for what you're trying to achieve in your area.

Ryan Spelman (33:30)
Yeah, I think that's a great overview of why one lab would use one procedure over another solution to extract the soil. Now, what I'll say about these recommendations as well, the recommendations on your soil tests are built, at least in Pennsylvania, with our lab based on field trials. So they use this Melloc 3 extractant to get these

build the profile of what nutrients are in the soil, and then they make recommendations. And those aren't just recommendations that they're choosing or deciding in a lab. They actually go out in the field and have a long history of trialing. Let's look at this result from this MELIC-3 test and then put a trial out there where we do fertility response trials. So we add the fertility at different rates and then look at what...

at what rate do we see a crop response and where do we see that crop response kind of plateau and then they build the recommendations on it. So one of the reasons, so that just adds strength to the recommendation and I think it's some good context to understand what you're getting with some of these protocols.

Dwane Miller (34:40)
You're right. they've been, I'd use the word calibrated. So they've been calibrated for our yield types and goals here in Pennsylvania. So it is important to understand that you're using an appropriate lab with that extract and calibrated for our Pennsylvania climate, not climate, but our Pennsylvania yield.

Justin Brackenrich (35:10)
And so in prepping for this I read a really interesting fact sheet from the Oregon Extension Service soil test interpretation guide, right? And I think the way they summarized it was probably the most real way I've seen this done is When you're in this low level, right if you look at a Penn State soil test your interpretations or your results are gonna say low optimum above optimum or below optimum optimum and above optimum and and the way that

They summarize this and they look at it is they say if you're in this below optimum That means yes, you will see a response From adding fertilizer right you are low enough when you're below optimum you put it out There is a significant chance over the years of data and calibration that that will improve your yield if you're above optimum What they're saying is there enough extractable nutrients for that plant in the soil that applying fertilizer? There's a low chance that you're going to see that change

And where they really got me is their middle they call that the maybe zone right and and so we call it optimum But when they're looking at it Maybe you will see an increase right? It's going to depend a lot on the weather and the soils and the crop and when it's applied But that optimum zone is where you can kind of say, I don't know. Maybe we should put a little bit on Maybe we should offset with removal But we look at this as yes, maybe no

you're kind of tabulating or deciding if it's worth the effort to put the soil test. And I thought that made a lot of sense in very relatable, understandable terms.

Ryan Spelman (36:37)
Yeah, definitely. And I think one of the other things that we were talking before this episode is that those recommendations are also adjusted based on the soil test, know, the, or sorry, the soil type, right? So the optimum in a clay-based soil might be different than how a sandy soil will respond. So that's just kind of another reason why using a local test that's calibrated to the local environment.

It is important.

Yeah, so I think we kind of jumped into this conversation about soil extractants. So just in case you're not aware, I'll give you just a snapshot of what happens when your soil test reaches a lab and how you get to a result of the actual plant available nutrients and then your recommendation. So what happens is you send the sample in, they get it, right? They will...

take that cup of sample and as Justin indicated, they'll grind it up real small and they'll take like a teaspoon of that soil to be tested. And first they do their pH test, okay, which is a separate test from this melloc three test that we were just talking about. Then they take another small sample and it goes through this extraction with the melloc three extractant and they take that solution.

And then that solution goes to what we call an ICP. And an ICP is just a spectrometer, so a device that measures the amount of all different types of compounds in there. And they know based on a standard of different, you know, they'll have a standard for potassium, phosphorus, all these things. They know where in that spectrometer all of these compounds come out in the chemical analysis. So that's how they get to how much

of all of these extractable nutrients are in your sample. And then they use that to make a recommendation. So that's kind of a really quick snapshot, you know, not in depth at all, but that's how we're getting these results. Okay, so maybe we can get to just cover a little bit about the results. And I think then our conversation will be wrapped up here.

So we go through that whole process and then in three to five days after you submit a sample, hopefully you'll get back a soil test report. Okay, so these soil test reports, there's an option that you can also add, copy someone else to receive the report. If you're unsure about how to interpret these, you can put your local extension educator there or someone else that you can rely on.

⁓ who can also get a copy of these results. And so why don't we talk a little bit, just really practically, we get this form, how do we interpret it?

Justin Brackenrich (39:25)
Dwayne, you want to start or you want me to start?

Dwane Miller (39:27)
Sure, no. you're going to get the form back either via email or postal mail. And it's going to have some bar graphs on it in the top section. And I'm going to give you a snapshot of where your pH, where your phosphorus, your potassium, and your magnesium are. And Justin, you just referenced it goes through three basic things.

areas of that graph, whether that's below optimum, optimum, or above optimum, gives you a quick snapshot of where those nutrient levels are at the current point. Then it's going to go and spill into your recommendations and then start with this limestone recommendation. Give you a recommendation in ⁓ either pounds per acre

on a field scale or pounds per square foot on a yard or garden type of of scale. And then your specific nutrient recommendations for the crops that you're going to plant on a three year cycle. Start with nitrogen. And again, that is based on the yield goal that you're providing for that specific crop.

and then your P205 and your K20, your phosphate and potash recommendations. So you can base your soil test nutrient levels on those recommendations. You can adjust them. If you're in the above optimum, it's going to tell you, all right, there's like

Justin said likely no crop response from adding additional nutrients. If you're in the optimum, you can base it on applying those nutrients based on crop removal. maybe some economics of fertilizer takes this into account. If we're in a period of high input prices and you're looking to sharpen that pencil when you're putting that budget together, maybe you're only looking to

put on for crop removal at this point versus building up into that optimum level. So different management strategies can be applied to how you wanna tackle your nutrient solutions, if you will.

Justin Brackenrich (41:40)
Yeah, I think that's like, you know, a really good overview of what you're looking at. so Ryan mentioned earlier, we're going to talk about the Penn State Analytical Services Lab report, and we're going to attach a file in the show notes about like interpreting these and how you can walk through them. So when you look at other labs or even even the Penn State, if I start there, like there is an enormous amount of information on this sheet, right? Sometimes it takes

Or agronomist right to kind of help you work through what some of this stuff is and you start getting and thinking about a calcium or excuse me the acidity or or the cation exchange capacity and base saturations Those are very popular ways for people to want to balance soils, right and there are these like golden ratios within base saturation And I think we can kind of get hung up on that a little bit, but I think just like Dwayne described What we're looking for is

these numbers over the course of that three years, right, of your next three cropping cycles, those are gonna offset deficiencies and also kind of account for some removal when you're looking at them, right? And so keeping these numbers where they are, when you test back in three years, you should be much closer to that optimum or that like maybe range of where you're gonna see a response or not. And when you haven't done soil testing for a very long time, a lot of these numbers come back very large.

Right, if you're in a perennial hay system, I see a lot of things all the time that are saying 250, 270 pounds of potash is what you're required to get out of the hole you're in, right? That's not an obtainable goal. And so I think that's where Ryan mentioned you can attach someone or add someone to the, I think that's where working with an agronomist can help you take this in more bite-sized pieces, right? I see people, they get them, they review it, they call.

A service agronomist and say hey, what can I do? Oh my gosh He's gonna cost me eight hundred and fifty dollars an acre a year to get out of this hole, right? And then they start to spiral or panic Don't let yourself go down that rabbit hole right call one of us call someone that you're working with and and let them talk you through how you make a plan to get over this hump and kind of start working towards that over the next few years

Ryan Spelman (43:52)
Yeah, that's a great point. Like these should be viewed as like this is your optimal recommendation. Right. That doesn't mean that it's the only thing you can do. Right. Like it honestly, oftentimes, if you need to apply that much, it really isn't what you should be doing. Right. It's it's how can we practically get there? And and that can be adjusted for a number of reasons. Right. And so so it is important to have this looked over as well by by someone who can help you if you are

unsure of how to interpret it.

Justin Brackenrich (44:24)
think

the hardest part for me when reviewing a soil test and maybe you guys feel this way too But someone calls and I'm looking at this example that says we need 60 pounds of phosphate and 70 pounds of potash and they say What's the best way for me to get that? That is such a difficult question for us to answer because we don't know what company you're work with We don't know if it's you know If it's a local co-op if it's somewhere else if you're wanting to buy bags of stuff if you're wanting to go in bulk

We don't know what these companies are going to have as an option for them to even blend or give you in bulk. And so like, if you can do a little bit of this research too and say, hey, I'm going to call my local agronomy supplier and I'm going to find a list of what fertilizers they have options to. That makes these calculations and that makes this so much easier for us because typically we're, if it's phosphorus, we're thinking either, you know, MAP or DAP, mono ammonium phosphate or diamonium phosphates, the best way to get it.

When we're thinking nitrogen, right? Is it urea? Is it uan? Is it ams? Is it you know, it just goes on and on and we can spin out a hundred different recommendations But when you call them like sorry, we don't have that doesn't right now. We're starting back over at square one

Ryan Spelman (45:35)
Yeah, I'm with you.

Justin Brackenrich (45:36)
Very good.

Dwane Miller (45:37)
important

to know what what your local supplier has because that's going to dictate the recipe that we're going to recommend.

Ryan Spelman (45:47)
Yeah, definitely. it's if you're too glued to these numbers, you can spend a lot of money just in saying like, know, maybe I need 200, zero, 100, you know, but I can't find a source that has that kind of ratio. Well, we need to find a ratio that's as close to the ratio that you need and then manage some of those, the the pros and cons of that, you know. And so that's where

taking this to if you have a trusted supplier of fertilizer as well, that's a great way to bring this test and have that conversation with them or you get that information from them and go to your educator, right? It's not a one size fits all kind of thing. Okay, so any other comments on interpreting a soil test? I think that's probably a good, and really that we have,

a more in-depth article that we'll link to this as well. So if you're really interested in looking at it, seeing it, and stepping through this process, we'll put that up as well.

Justin Brackenrich (46:49)
So the last thing I want to mention is about trace elements or your micronutrients, right? In our our Penn State soil test will give you zinc, copper and sulfur. It's very popular to have some of these other labs where they can test a lot of these and I'm by no means an expert in this, but I've had a lot of conversations with people that are. And I think that these are kind of challenging to use in a way that's going to work you through like a fertility program, right? A lot of times

So sulfur, for example, right? And the one I'm looking at says 9.5 parts per million. Sulfur is very similar to nitrogen in this aspect of we're thinking at removal rates, right? If you're a legume crop, you might be 20 to 30 pounds. If you're a grass forage, it might be 15 to 20, right? And there are these ratios of 10 to one nitrogen to sulfur when you're applying these things. When we put out sulfur and we soil test, right? We're soil testing in that top.

six, seven, eight inches. If we're in a perennial forage, it might only be three or four. But what is happening with a lot of our sulfur and research at the university shows this is it's leaching out of the top but being trapped in the subsoil in that 18 to 24 inch mark. And so if you're using this topsoil as your metric and saying, well, there's nothing up here. We got to apply all this to it.

Especially in perennial systems where you've got really deep roots that can grab some of that stuff These numbers just don't match right like you might have a very good sulfur profile deep and now you're treating for the top because this soil test says you need 26 pounds of sulfur because it's not in the top right and I think the same thing can happen with zinc and boron and as we mentioned with timing These these extractions what they're designed to do is mimic a plant root and what the plant can get

Right? And so if the sulfur or the zinc or something is in a form that's not plant available, it's not going to really show up in this test. And if you're taking them in the fall and it's cool and wet and really overcast, we start to see like zinc be a lower number, right? We see zinc deficiencies in corn a lot in the spring because it's cool and it's wet. Soon as the sun comes out, soon as it dries out, zinc's back out there. So all of this is just kind of this long winded way to say, be careful.

when you're looking at trace elements and try and judge everything with them. They're incredibly hard to research. They're incredibly hard to calibrate the way that we've done with phosphorus and potassium. And I think before you just kind of sign off and say, this is my prescription, I need all of these things, I think you should do a little research with your own extension and your own area to see what people are thinking works within your soils and profiles.

Dwane Miller (49:31)
Yeah. think that's very sound, Justin. Very sound advice.

Ryan Spelman (49:36)
Yeah, and I will say, know, a lot of times when we're talking about these trace elements, this is where we get into looking at deficiencies, right? Like, this is where we look at the evidence of something that's not there. We don't look at our soil to see like how much of it, because it's trace, right? Like it's not something that's really correlative, you know, based on your soil type for all the reasons you just talked about. And so for that reason,

Um, this is where we look at the crop. And if we see something that might be a nutrient deficiency, um, we should go about, um, doing some plant tissue testing, right? So we have a, um, uh, episode on exactly that. If you go back to season three, episode 24, we talk a lot about this and, and how we actually take plant tissue set, um, test to look for some of these deficiencies and how we can interpret them. Like, is this actually a problem with

adding that fertility or was it really wet or you know, there's a lot of questions downstream of that, but that's probably a better way to actually understand that.

Justin Brackenrich (50:39)
Very early in my career and maybe this set the tone for my feeling about this, but I worked with a producer. was in Butler County, Pennsylvania, kind of middle of the state in the West. And he had a cornfield that parts of it were showing a lot of this deficiency rate. saw a lot of this yellow streaking in it. The other part was a dark green looked beautiful. We went in, we soil sampled and we tissues tested the good and the bad. And what we found was

Basically the lower lying areas in that soil were suffering from zinc deficiencies right because it was wet it was cold Plant tissue was below sufficiency The soil was showing that there wasn't any there you took 20 steps to your right or your left or something a little higher Soil test levels were good on zinc and crop tissue samples showed sufficient in zinc right and that can tell you how hard it can be to chase some of these

across these fields early in the spring. And that's why it's very popular to have a little bit of zinc as a starter or, you know, throw some sulfur out there because then we don't have to worry about phosphorus starters the same way, right? That stuff's cool. It's wet. It doesn't move. these are some of these real life things that you see. And I just want people to be cautious before they go all in on some of these programs.

Ryan Spelman (51:52)
Definitely, and I think on that, maybe this is like the, can talk a little bit about some practical advice and we'll leave you on that. think the trace elements, that's a really important part of this conversation. Other practical stuff, I always, one thing that we didn't touch on that I always try to cover when we're talking about soil testing, really soil testing is one of the most affordable things you can do to reduce the cost that you incur on a lot of inputs. So, you know,

the soil test is $10 and that $10 can go a long way when you're adjusting your fertilizers, your input costs, your limes, because you're really gonna, that $10 goes a long way in making sure you're actually putting out what will get you a crop response. So I just wanna make sure you said that.

Justin Brackenrich (52:41)
But I'm, Duane may have a different opinion of this, but I'm not sure there's anything else you can do on your farm that's any cheaper that has the potential to save you any more money than a soil test.

Dwane Miller (52:50)
I would agree 100 % you know, in my mind here I am going, all right, it's a $10 soil test. If we have a five acre field over the course of three years, what are we talking here?

Justin Brackenrich (53:04)
when phosphorus is 900 plus dollars a ton, right? You know, I mean, it doesn't take very many changes in pounds per acre to offset $10 with these kinds of fertilizer prices.

Ryan Spelman (53:15)
And to the inverse, also doesn't take much yield to, right? So if you're finding that, wow, I actually have to spend a little bit more on fertilizer, but the benefit will pay that back as well, you know, like so, so there.

Justin Brackenrich (53:31)
Socials of corn pays for it in the first year,

Ryan Spelman (53:34)
Right, right, exactly. Yeah, yeah, so. Yeah, so I think that's a that's a good note. Anything else before we close this out or do think we did a good job here?

Justin Brackenrich (53:46)
I think this was a great starting point for Back to Basics. I hope everyone, you know, I hope you learned this, right? And take it for what it's worth. We're not trying to change anyone's mind on where they send their tests. We're not trying to change anyone's ideas of how they're running their farm. What we're trying to do is just give a little bit better foundation and understanding of why soil testing happens and why it's important on your operation.

Dwane Miller (54:09)
Amen.

Ryan Spelman (54:10)
Awesome. Well, great way to end it. Justin, Dwayne, I appreciate you guys all jumping on here today to talk about this. thanks guys and to our listeners, thank you all for listening to us. And I hope got something out of this Back to Basics episode and we'll do some more of these in the future. We'll see you on the next episode of the Agronomy Highlights podcast.