▶ Phosphorus Fertilizer Enhancement Products: Real Value or Just Extra Cost?

0:05
All right, so I said earlier, my name is Rianne Wagner and I’m a master’s student under Dr. Shawn Conley and the Soybean and Small Grains Lab, AKA, the Cool Bean program at UW Madison.

0:16
And today I’m really excited to talk to you guys about phosphorus fertilizer enhancement products and whether they add real value to your operations or are just an extra cost.

0:25
Now, if you follow the Badger Crop Network website, you might know that we posted an article on this topic back in January.

0:35
And if you’re interested in taking a look at that article, feel free to scan the QR code on screen.

0:39
Don’t worry if you’ve missed the QR code right now, it’ll be up again at the end of the presentation.

0:44
All right, so getting started here, I first wanted to give a broad overview of phosphorus fertilizer enhancement products and what they claim to do, which is essentially to increase the plant availability of applied phosphorus fertilizer.

1:01
And companies will say that their products accomplished this through methods such as slowly releasing phosphorus into soil, boosting phosphorus mineralization rates or decreasing phosphorus fixation rates compared to a typical application of phosphorus fertilizer.

1:16
And so the ultimate goal of this presentation is to break down the science behind these fertilizer enhancement products so that producers can critically evaluate company claims and determine if these fertilizer enhancement products make sense economically and scientifically for their operations.

1:34
So, before we dive any further into phosphorus fertilizer enhancement products, I thought it would be good to back up a second and talk about phosphorus plant availability as that is really key to understanding how these products work.

1:47
So there is a lot of phosphorus in our soil in many different forms, but only about 1% of the total soil phosphorus is plant available, meaning that the majority of the phosphorus in the soil is not accessible to plants.

2:02
When you apply phosphorus fertilizer to the soil, the majority of that applied phosphorus goes directly into the available soil solution phosphorus pool.

2:12
However, phosphorus in this available pool is subject to many complex soil processes that can render it unavailable.

2:20
And understanding the processes that transform phosphorus to become available or unavailable is really important to understanding the science behind phosphorus fertilizer enhancement products.

2:32
So the two soil processes that we’re going to cover today that are the most important to understanding phosphorus fertilizer enhancement products are fixation and mineralization.

2:43
So talking about fixation first, you might be familiar with nitrogen fixation, but phosphorus fixation is a little different.

2:49
It’s a general term that refers to when soil solution phosphorus becomes unavailable.

2:55
And if you’re familiar with phosphorus fertilizer enhancer products and have read labels or company claims, you’ve probably heard of the term fixation, as companies very often use this term.

3:06
But what they really mean when they’re saying fixation is adsorption, which is when available phosphorus binds to positively charged elements in the soil and becomes unavailable.

3:15
Now adsorption is a very pH sensitive process as in acidic soils phosphorus binds to aluminum and iron, and in alkaline or neutral soils, phosphorus is going to bind to calcium.

3:27
And since phosphorus fertilizer enhancement companies refer to adsorption as fixation when talking about their products, I’m going to use the term fixation for the majority of this presentation.

3:38
But just know that what I’m really referring to is adsorption and it’s really important to note that fixation is not a permanent process.

3:47
It is reversible through processes such as desorption and dissolution.

3:51
However, the rate of these reverse processes is much slower compared to the rate of fixation itself.

3:58
Moving on to mineralization, it is a biologically mediated process where mediated by solar microorganisms on plant roots that secrete enzymes which transform organic unavailable phosphorus to plant available phosphorus mineralization occurs at a standard rate in all soils and it’s important to know that once phosphorus is mineralized and becomes available, it can be subject to other soil processes such as fixation that could render it unavailable again.

4:27
So now that we understand a little bit more about how phosphorus availability works in the soil, I think we’re ready to dive back into these fertilizer enhancement products and what they’re designed to do, which is to boost mineralization processes in the soil and decrease or inhibit fixation processes in the soil.

4:45
With the ultimate goal of these products being to increase the efficiency of phosphorus fertilizers, which allows producers to increase their plant available phosphorus while cutting back on fertilizer applications.

4:56
It’s important to note that these products, some of these products, do contain phosphorus while others do not.

5:01
And they’re meant to be applied before, after, or with your typical phosphorus fertilizer application.

5:08
Phosphorus fertilizer enhancement products usually accomplish their goal of increased phosphorus efficiency in one of three ways, which allows us to place them into 3 distinct categories, which are slow releasers, blockers and enzyme products, which we’re going to break down further in the upcoming slides to understand the science behind these products and evaluate the claims that companies may make.

5:30
So first, talking about slow release products, they improve phosphorus use efficiency through limiting fertilizers contact with reactive components of the soil and they accomplished this through reducing fertilizer surface area and contact time of the soil.

5:44
So essentially the more time available phosphorus has to react with the soil, the more likely it is that it’s going to form stable bonds of soil particles and precipitates and migrate to slowly reversible unavailable soil phosphorus pools.

5:57
So by using a product that slow releases phosphorus over the course of a growing season, the opportunities for stronger phosphorus bond formation are decreased.

6:05
And some companies may claim that phosphorus availability is better synchronized crop demand, although there isn’t a ton of outside research that validates these claims.

6:14
So when thinking about a classic example of a slow released your product, you’re really thinking about your coded map adapt fertilizer.

6:20
As seen in the picture on the screen.

6:22
Everyone’s pretty familiar with coated fertilizers.

6:23
They’re nothing new, but essentially they provide controlled release of phosphorus through reducing contact between the fertilizer and the soil.

6:33
Moving on to blocker products, which may be a little more exciting.

6:37
They contain negatively charged compounds that react with positively charged soil cations, allowing phosphorus fertilizer to remain in the available soil solution pool.

6:46
It’s important to note that blockers do not contain any phosphorus compared which compared to solar releasors which typically do contain phosphorus.

6:54
So you’re applying your phosphorus your your blocker products in combination with phosphorus fertilizer.

7:00
And as blocker products act on fixation, this means that soil pH is a very important consideration when you’re thinking about using one of these products.

7:09
As you can see from the graph on the right, when you’re in the neutral soil pH range, which is from like 5.7 to 7.7, you’re currently getting the maximum plant available phosphorus and fixation is relatively low in the soil.

7:23
When you get outside of this range, that’s really when your phosphorus begins to become subjective fixation and is bound to iron and aluminum or calcium in the soil.

7:32
So this means that if you’re considering using a blocker product and you have a neutral soil pH, there really isn’t that much that it’s going to do as there are very little, there’s very little fixation going on for it to block.

7:47
When looking at an example of a blocker product, the maladic aniconic polymer is a very popular, well studied blocker product and it is applied as a fertilizer coating or mixed with liquid formulations of fertilizer.

8:00
And essentially how it works is that the polymers in the product react with positively charged chemical elements that precipitate or absorb soil phosphorus, which protects available soil phosphorus from undergoing fixation reactions and increases available soil solution phosphorus.

8:15
As this is a very well studied product, there was a great meta analysis that was done that combined data from a ton of different studies to essentially answer the question, does this product work and under what conditions?

8:26
And what the study found was that yes, it worked, but it was very context specific.

8:31
So, when they applied this polymer product, which goes under the trade name of AVAIL, to sites that were likely to respond and sites that were likely to respond were categorized as sites with extreme pH less than 5.7 or above 7.7, sites with low soil test phosphorus, and sites that had reduced phosphorus fertilizer rates, There was a 4.6% additional yield increase due to use of the product.

8:53
However, when they applied the polymer to sites that were unlikely to respond, which were sites that had neutral pH, had high soil test phosphorus and high phosphorus fertilizer rates, there’s only 1.3% additional yield increase due to the product.

9:07
So yes, the product did work, but whether it’s an economically sound incorporation to your management practices really depends on what type of sites you’re applying it to.

9:20
So finally getting to our last category of fertilizer enhancement products, enzymes contain microorganisms or the enzymes themselves that stimulate the mineralization process of the phosphorus cycle, which supposedly leads to improved phosphorus efficiency and plant microphosphorus acquisition.

9:36
And this is diagrammed in the image on the right where you can see that microbes or enzymes themselves are applied to the soil, which then transform insoluble unavailable phosphorus to plant available phosphorus, which is then available for plant uptake.

9:50
This all sounds great in theory, right?

9:52
But there are a couple hurdles that this product has to overcome in order to be effective, but the main one being that has to dominate the soil’s background biology.

10:02
So soils already come in built in with their own microbiome and their own existing set of microorganisms and enzymes.

10:08
And usually it’s a pretty thriving healthy community.

10:11
So in order for these enzyme products to work, they essentially have to dominate and out compete all of the enzymes and microorganisms already in the soil and establish themselves in the community.

10:23
And then once enzyme product is able to do that, it has to boost the standard mineralization rate in order to increase mineralization.

10:32
And this is a a pretty tough ask and there’s not a ton of outside research on these products.

10:38
So it’s kind of a question mark of whether these products are able to accomplish these two tasks.

10:45
But lucky for us, I was able to work with a producer this past summer to complete an on-farm study where we looked at an enzyme product that contains A phytase enzyme which releases phosphorus from phytate.

10:57
Now you may be wondering what phytate is.

10:59
I was as well when I first learned this product.

11:02
But phytate is an organic form of phosphorus.

11:05
And just a reminder, organic phosphorus accounts for 40 to 95% of total phosphorus in the soil and phytate can account for 50 to 80% of organic phosphorus in the soil, meaning that in some soils, phytate makes up a large portion of the total phosphorus in the soil.

11:22
However, because it’s organic, it’s unavailable to plants and needs to be mineralized in order for it to become plant available.

11:28
And that’s where the phytase enzyme comes in to mineralize it and make it available for plant uptake.

11:34
So now that we know a little bit more about this product, we’re ready to get into the study.

11:40
And we performed the study on corn in Beaver Dam on a farm there and those pretty standard management practices.

11:47
We planted on May 25th at 37,900 seeds an acre. Used a standard DeKalb BT2 Pro variety.

11:55
Nothing much to note else.

11:56
Nothing much else to note about the management practices, but looking at the historical soil test values, we were able to see that it was a pretty optimum testing field.

12:06
There were a couple pockets where there was low solar test phosphorus, but it was really on the high end of the low range.

12:13
So, we’re really not concerned about deficiency and there is plenty of plant available phosphorus for uptake.

12:19
Another thing to note is that the pH of the field ranged from 5.7 to 6.6.

12:24
So again, there was no real concern there and we weren’t really worried about fixation transforming available phosphorus to unavailable.

12:34
Getting into our treatments now, we had three treatments.

12:36
Our first is essentially control where no starter fertilizer was applied.

12:39
Our second was a starter application of 10-34-0 at 5.75 gallons an acre.

12:44
And our third treatment was the same as treatment #2 but we added the phytase enzyme at 2.5 fluid ounces an acre. For our analysis,

12:55
the first analysis that we did was an in season soil analysis where we took soil cores 2 weeks post-plant on June 3rd and we sampled in row in order to compare the BRAY 1 phosphorus soil test values between treatments.

13:07
And as you can see, treatment #3 that included the phytase enzyme did not outperform our control or our standard phosphorus starter fertilizer application.

13:19
We also performed a tissue analysis.

13:20
We tissue sampled around V10, got that analyzed for phosphorus concentration, and you will see the percents on the graph here.

13:26
And again, we did not see treatment #3 with the phytase enzyme outperform our control or our standard starter fertilizer application. Which leads us to our preliminary conclusions with our first one being that the soil and tissue test analysis did not show any statistically significant effects of the product.

13:46
No extra phosphorus was unlocked in the soil, and our phosphorus uptake rate and tissue concentration was not boosted when we did our tissue analysis.

13:55
But when evaluating these products, yield really is the ultimate indicator of whether this product will be a worthwhile investment.

14:02
And we look forward to getting yield results to you guys later this fall after harvest when we’ll likely post something on the Badger Crop Network website.

14:13
So now that we have a grasp of how phosphorus availability works in the soil, we know the goals of phosphorus fertilizer enhancement products and the different categories they fit into.

14:22
And we’ve looked at an on-farm study evaluating an enzyme product.

14:26
I think we’re ready to answer the question, are phosphorus fertilizer enhancement products right for your operation?

14:31
And I think we can pretty confidently say that these products are not a silver bullet for phosphorus management.

14:39
Don’t get me wrong, I definitely think they have their time and place, especially when you have extreme pH conditions and are worried about phosphorus fixation in your soil.

14:48
If you find yourself in that scenario, using one of these products such as a blocker product could help limit phosphorus fixation and help the applied phosphorus fertilizer remain in the available soil pool.

15:01
Another scenario that could be helpful is if you find yourself with low soil test phosphorus conditions and you are unwilling or unable to apply the recommended phosphorus fertilizer rates.

15:12
I want to be clear, these products are not meant to replace applying the recommended phosphorus fertilizer rates and you will not get the same effect by substituting phosphorus fertilizer with these products.

15:23
But if you are going to cut back on your rates and you want to try using one of these products, they could help limit some of the yield drag you’re going to see due to the low soil test phosphorus conditions and phosphorus deficiency.

15:36
But for most producers who do not have low soil test phosphorus conditions in extreme pH, these products really are unlikely to have a significant effect as there is plenty of available accessible phosphorus in your soil for plant uptake and you don’t need a product to help that.

15:53
If you do think that these products could be right for you and want to do more research, another difficult, like a hurdle you may find yourself running into, is that there’s not a lot of peer reviewed academic research that validates company claims.

16:07
Company research is great.

16:09
I love it when companies do their own research and make it accessible for consumers.

16:13
However, sometimes this research can be biased and is not quite realistic.

16:18
So making sure that you’re validating whatever companies are saying with outside sources of research is really important.

16:26
And when those peer reviewed academic sources don’t necessarily exist for a product, it can be really difficult to evaluate whether a product is right for you.

16:36
So while we established that these fertilizer enhancement products are not a silver bullet, I think they are still a useful tool in our toolbox, especially when combined with recommended phosphorus management practices.

16:48
The first of which being utilizing the 4R’s of nutrient management, which just as a reminder are Right rate, Right time, Right source, and Right place.

16:57
Right source essentially means that you’re matching fertilizer type to crop need.

17:01
Right rate means you’re matching the amount of fertilizer applied to crop nutrient uptake.

17:04
Right time ensures that nutrients are available and crops need them.

17:07
And Right place means that you’re applying nutrients where the crop can access them, ideally in the root zone.

17:14
Soil pH is also really important when it comes to phosphorus management.

17:17
I hope if you take away one thing from our conversation today is that phosphorus or phosphorus availability is really determined by soil pH, especially with fixation.

17:27
So, ensuring that you’re managing your phosphorus in the optimal, your pH in the optimal range, which is 5.7 to 7.7, but ideally closer to 6 to ensure that you’re limiting fixation reactions and keeping applied phosphorus available is really important.

17:44
Next, it’s really important that we’re applying phosphorus at crop removal rates.

17:47
This ensures that we’re not drawing down the available phosphorus pool and that the following crop has plenty available phosphorus to access during crop growth.

17:56
And finally, if you do find yourself testing below the optimum soil range, make sure that you’re building and maintaining phosphorus in that optimum range to maximize yields and prevent phosphorus deficiency.

18:09
So wrapping it all up, I wanted to revisit this image from the first slide as I think we have some new perspective, new knowledge that allows us to evaluate these products.

18:21
And while it may be great that companies claim their products release phosphorus solely into the soil, boost phosphorus mineralization and decrease phosphorus fixation, if we are already following standard phosphorus management recommendations, we really don’t need a product to help boost our available soil phosphorus.

18:37
We have plenty of available soil phosphorus already in the soil for crop uptake and it’s unlikely that one of these products is going to have an effect.

18:45
And if you are going to be using one of these products, it’s really important that you’re using this product or one of these products in addition to recommended phosphorus fertilizer management practices, Everything I talked about on the previous slide, making sure you’re still doing that if you’re using one of these products.

19:02
And it’s also really important to do your research.

19:04
Make sure you’re researching these products both online and in the field before you fully commit.

19:09
When you’re researching online, make sure you’re not just looking at company research.

19:12
Try and find outside sources that validate what the company is saying to make sure that the product is applicable for your needs.

19:20
And then if you’re able to test the product in a field, apply it to a small portion of your field and see if it’s effective,

19:26
will ensure that the product is right for your operation and will actually work.

19:30
And finally, when it comes to phosphorus management, we really want to be sure that we’re pulling routine soil tests to ensure proper phosphorus management, which means that we’re soil testing every four years for most fields and every two years for sands and sandy loans.

19:43
And this allows us to make sure we’re applying the correct phosphorus fertilization rates and we’re not facing or dealing with any phosphorus deficiency.

19:51
All right, that wraps up my presentation On the left there we have the article I was talking about in the beginning about phosphorus fertilizer enhancement products.

20:00
And on the right, I included a publication from UW-Extension about sampling soils for testing.

20:05
I’m happy to take any questions now.

20:11
Thanks, Rianne!

20:12
That was awesome!

20:13

20:17

20:18
In your research, did you see any times when products increase phosphorus are potentially at potentially the wrong time?

20:26
Any examples?

20:28
I don’t think I ever saw that.

20:31
When I with my research that I saw, it was usually looking at, there wasn’t a lot of in season data.

20:37
It was just kind of looking at yield.

20:39
That’s usually what these like these companies are evaluating.

20:41
They’re not actually taking soil tests or tissue tests.

20:44
They’re mainly just looking at the impact on yield.

20:49
So if you were advising a farmer, what 3 questions would you ask before recommending A phosphorus enhancer?

20:55
If you had to narrow it down to just three?

20:59
OK, I would ask first of all whether they own their land.

21:04
I think that that’s a big consideration when it comes to people’s willingness to apply nutrients to their field.

21:12
And so it’s, it’s more understandable if they want to cut back on fertilizer rates if they don’t own their land.

21:17
I would also ask about their soil pH ’cause if that’s outside of that range of 5.7 to 7.7, we could be dealing with some phosphorus fixation that could be improved with an enhancement product.

21:30
And then finally, I would ask about their soil test levels as if they’re in the optimum range, there really is not a great need for using one of these products.

21:40
Awesome.

21:41
We did have one other one that was sort of aligned with the other one, but if you have any different messages to share with this one, this was the last one of these products hold phosphorus over winter or how do they work in different weather conditions?

21:54
Oh, I think when I was looking at a lot of these products and doing my research, a lot of these companies claim that their products work under all conditions.

22:05
It doesn’t matter whether you irrigate, whether it’s dry, whether a lot of sand, a lot of clay.

22:11
So I think being good stewards of the land, we don’t want to apply phosphorus to our fields when there’s dot crops on it in the fall.

22:20
So maybe don’t apply an enhancement product in the fall when there’s nothing on your field.

22:26
But most products made it clear that you could apply just these products are really incorporate easy to incorporate into your typical fertilizing management practices.

22:34
So that makes it really easy to just if you’re fertilizing your field and you want to throw one of these products in, they make it easy for you to do that.

22:40
So you don’t have to worry about applying in the fall and then you unlock phosphorus that then runs off or is not available by the time and see what comes around.

22:51
Gotcha.

22:53
All right.

22:54
Well, I do, I do understand that the QR code and maybe has been deactivated for one of these QR codes on the slide.

23:01
So we are aware of that.

23:02
If anybody is having issues with that or has questions or wants direct links that maybe we’re not presented already, just go ahead and let and let us know and we’ll get that to you.

23:11
So see.

23:13
Well, thank you so much, Rianne.