soil tests = no P or K is needed ???

[americanlawn]

If soil tests show that P & K are not deficient, are these nutrients still needed (especially potash)?

(Results from over 200 soil tests we did a few years ago revealed deficiencies only in nitrogen and several micro nutrients)

So if a bag of 44-0-0 slow release fert costs the same as 28-4-6, or 31-3- 5, or 34-0-5, why not go with the 44-0-0 XCU or PPSCU at a lower rate to increase profit?

Any thoughts? Negatives/positives? Timing? What are your thoughts/experiences? Just curious - been wondering for a long time. Thanks

[rcreech]

If soil tests show that P & K are not deficient, are these nutrients still needed (especially potash)?

(Results from over 200 soil tests we did a few years ago revealed deficiencies only in nitrogen and several micro nutrients)

So if a bag of 44-0-0 slow release fert costs the same as 28-4-6, or 31-3- 5, or 34-0-5, why not go with the 44-0-0 XCU or PPSCU at a lower rate to increase profit?

Any thoughts? Negatives/positives? Timing? What are your thoughts/experiences? Just curious - been wondering for a long time. Thanks

Larry,

Here is my take on the subject.

Typically Nitrogen isn't listed on a soil test and it is one of the most mobile nutrients and by the time you pull the sample and get the results it would have already changed...especailly if not packages and dried correctly.

Is that something you request? Any just wondering why you would.

If you have a soil test where P and K is adequate...I feel there is no reason to add more.

P and K are both imobile in the soil (at the levels you see in a lawn situation) as you don't have to worry about them moving unless you have soil loss or plant uptake and removal. In a lawn situation neither of these issues should become a reason.

Now if the customer removes clippings this would maybe make me think the other way because now you are dealing with nutrient removal.

I don't put any P on any of my lawns and I do run a little K with my 30-0-10, but at the end of the day I am putting very little K down.

Why buy the P and K and then add it where not needed. Nobody benefits from it and you pay for it out of your bottom line!

[americanlawn]

Thanks buddy -- that's what I was kinda wondering. We've never used a 44-0-0, etc after April 1st or before late October, but I've always wondered why. I spose cuz my sales reps recommended what others were using??

Several years ago, we used alot of "synthetic-organic" liquid fertilizers. Main reasons: low salt content, no chlorene, and they offered several micro's we could not buy in a bag. We thought this was the way to go.

http://www.agroliquid.com At that time, they were mostly agriculture oriented, but they began to offer turf & ornamental formulations too. They were attempting to expand into our market with their turf & ornamental formulations, so they offered us free soil samples. They took soil samples from approx 214 of our accounts throughout central Iowa. Then they sent them to an independent lab for final results. All this was free to us.

Just under half of the samples were taken from "loam" soils, and the rest consisted of "clay" soils. Loams soils didn't lack much (just a little nitrogen for the most part), but nearly every "clay" soil indicated a huge lack of nitrogen -- along with deficiencies of several micro's (mainly iron, manganese, zinc, copper, and boron).

We never requested to include/exclude nitrogen as part of their soil tests, but they did. Regarding mobility in the soil, I was told that iron was even more mobile in the soil than nitrogen. Go figure.

[phasthound]

Good info guys. How much of the P & K in the soil is plant available? I think it's also important to be adding some organic matter along with NPK. By providing food sources for soil microbes you can enhance nutrient uptake. It is the microbes that mineralize nutrients into plant available form.

[americanlawn]

Thanks Barry. I has hoping you would chime in. Not sure about how much available P & K cuz we didn't personally take soil samples. Figured those guys knew what they were doing. They're mainly into Midwest farming (I think).

But I'm with you regarding organic matter. So is my brother (who runs our IOWA family farms). Sh$t ---- I'll even listen to Rodney (even though he's from Ohio:hammerhead:) :laugh::laugh: (Sorry rcreech) :laugh:

Seriously, my brother has run his share of "honey wagons". Also prefers "no till", etc whenever possible. IMO turf/ornamental care benefit from the same values. Weird but true, cuz most plants/soils have similar needs.

I'll shut up now and hope for other feedback. Thanks.

Good info guys. How much of the P & K in the soil is plant available? I think it's also important to be adding some organic matter along with NPK. By providing food sources for soil microbes you can enhance nutrient uptake. It is the microbes that mineralize nutrients into plant available form.

[grassman177]

i have been thinking the same thing larry. i can not lose turf vigor and save money and not add unneeded minerals to the soil , all in one bang.

it is still needed during seeding and fall time to have extra that is soluable as much is locked up and large amounts are not available at once for the extra root boosting.

[DA Quality Lawn & YS]

Good thread Larry. I have run a few soil tests on our clay tight-as-heck soils around here in so. MN and found P and K to be ok and was also told they are tightly held in the soil structure. So, then why not just run xx-0-0 ferts with some select micros?

[Smallaxe]

i have been thinking the same thing larry. i can not lose turf vigor and save money and not add unneeded minerals to the soil , all in one bang.

it is still needed during seeding and fall time to have extra that is soluable as much is locked up and large amounts are not available at once for the extra root boosting.

The bad thing about adding P at seeding time, is that, P inhibits the activity the activity of AM Fungi. AM Fungi is better for the vitality of your new grass, in the long run... :)

Therefore, I believe. that additional P is not needed for seeding; especially if there is plenty there at this time. In fact, there may be too much, P already, for healthy AMF to grow in the plant.

[Jason Rose]

Ok, here's my question, other than actual science, we were always told to use a "balanced" fertilizer 3:1:2 ratio usually. Then prices of materials start going sky high and in order to keep prices down for the customers (us from the fertilizer suppliers) they started ommiting the P out of the mix. Then K began to rise in price dramatically and now they are omitting it as well. At first everyone was mad because it was going to be bad for the lawns to be only applying N all the time... Then some started looking at the real science of it, and now we question why we were using the "balanced" fertilizers in the first place!

I too have had a few soil tests done, and same results here. P and K are generally "high to very high" in the soil. BUT... We know they are also generally "locked up" in the soil. Does this mean they aren't really available for plant uptake? If that's the case, then when we add some via fertilizer, is that being taken up by the plants or is it just going into the soil profile and adding to what's there already? If the plants aren't able to use what's in the soil because it's locked up, and they can use, and need, what we are adding with fertilizer, dosn't it make sence to continue adding it? Instead of soil samples shouldn't we be doing tissue sample testing to determine what the plants NEED, not what's in the soil. Or a combination of both and see what's there and what's needed, and if what the plants need is already there, finding a way to 'unlock' them in the soil.

[Kiril]

Typically Nitrogen isn't listed on a soil test and it is one of the most mobile nutrients and by the time you pull the sample and get the results it would have already changed...especailly if not packages and dried correctly.

This is true for nitrates with respect to leaching, ammonium is less prone to leaching. Sample handling is really only a factor with regard to contamination, however if you want to get an N breakdown (i.e. nitrates and exchangeable ammonium), then you should air dry the sample. That said, I believe total N is the better test to get for management decisions in the landscape, so proper drying becomes a less important issue.

I do agree that field determination of N availability (nitrates in particular) will provide a better picture of your soils current N status, but not really necessary for your typical landscape IMO.

If you have a soil test where P and K is adequate...I feel there is no reason to add more.

Agreed

P and K are both imobile in the soil (at the levels you see in a lawn situation) as you don't have to worry about them moving unless you have soil loss or plant uptake and removal. In a lawn situation neither of these issues should become a reason.

Any ion in solution can be leached. Positively charged ions (cations) are less prone to leaching losses, but that does not mean it cannot occur.

Good info guys. How much of the P & K in the soil is plant available? I think it's also important to be adding some organic matter along with NPK. By providing food sources for soil microbes you can enhance nutrient uptake. It is the microbes that mineralize nutrients into plant available form.

Microbes mineralized some nutrients, not all nutrients.

I too have had a few soil tests done, and same results here. P and K are generally "high to very high" in the soil. BUT... We know they are also generally "locked up" in the soil. Does this mean they aren't really available for plant uptake?

Out of the two, P is more likely to be found in non-labile pools (i.e. not plant available) than K. Organic matter will help keep P in the active and labile pools.

If that's the case, then when we add some via fertilizer, is that being taken up by the plants or is it just going into the soil profile and adding to what's there already? If the plants aren't able to use what's in the soil because it's locked up, and they can use, and need, what we are adding with fertilizer, dosn't it make sence to continue adding it?

This would be the reason why many times you will find high P in soils that are continuously fertilized with a "balanced" program.

Instead of soil samples shouldn't we be doing tissue sample testing to determine what the plants NEED, not what's in the soil. Or a combination of both and see what's there and what's needed, and if what the plants need is already there, finding a way to 'unlock' them in the soil.

As noted above, increasing your SOM will help keep P available for plant use. Encouraging mycorrhizal associations with your plants will also help.

The way I look at it ... soil sample to guide soil management decisions, tissue sample to determine/fine tune observed problems with your plants. If you observe a problem with your plant(s), you really need both tests to determine the best course of action. A tissue test alone won't give you enough information to effectively manage your soil, and a soil test alone may not give you enough information to manage a plant deficiency. Reason being .... some observed problems may not even be related to nutrients at all, but rather other management/environmental factors the affect plant nutrient uptake/availability and/or plant health.

[americanlawn]

A hort school professor always said healthy plants need approximately:

50% growing medium
25% water
25% air

I know pH, soil type, etc, etc are also important, but his rule of thumb has always stuck with me. Anybody else ever hear of this?

[phasthound]

A hort school professor always said healthy plants need approximately:

50% growing medium
25% water
25% air

I know pH, soil type, etc, etc are also important, but his rule of thumb has always stuck with me. Anybody else ever hear of this?

Yes, here is the basic pie chart of healthy soil. As you noted, many other factors have impacts on plant health.

[greenskeeper44]

The bad thing about adding P at seeding time, is that, P inhibits the activity the activity of AM Fungi. AM Fungi is better for the vitality of your new grass, in the long run... :)

Therefore, I believe. that additional P is not needed for seeding; especially if there is plenty there at this time. In fact, there may be too much, P already, for healthy AMF to grow in the plant.

I have read this from many threads but I cant find any research to prove that statement. Do you have any?

[phasthound]

I have read this from many threads but I cant find any research to prove that statement. Do you have any?

It's very well documented, A 10 second search & just a quick quote from: http://mining.state.co.us/TechnicalBulletins/MycorrhizaAndSoilPhosphorusLevels.pdf
Research by Abbott and Robson (1979) concluded that levels of soil phosphorus
greater than that required for plant growth eliminated the development of the
arbuscles of vesicular-arbuscular (VA) types of mycorrhizae. Arbuscles are
structures produced within the host plant cells by the VA mycorrhizae. These
structures are responsible for the transfer of absorbed nutrients from the fungus to
the plant. The arbuscles resemble miniature shrub-like trees (arbuscular = shrub in
Latin). Mosse (1973) reports adding phosphate results in no arbuscles forming.

[americanlawn]

Thanks Barry. Makes sense.

Seems during the past 35 years or so, most homebuilders are now required (by law) to have a "95% compaction rate" (for foundations) in order to minimize "settling". This is probably why we see "good soil" (loam) in older neighborhoods compared to the "subsoil (clay)" soils we see nowadays in newer developments.

To me, these newer properties would benefit from organic matter --such as your products (good stuff), core aeration, additional water, etc to make lawns healthy & look nice.

Prob is, many of these customers are lazy......even if they have a sprinkler system, they're often too cheap to use it (yet they'll sign up for core aeration). Most just want to pay a lawn service to come out & "put stuff on" and expect their lawn to the nicest in the neighborhood. Go figure. Then too many will go out & mow/trim way too short. Life goes on. :laugh:

[phasthound]

Thanks Barry. Makes sense.

Seems during the past 35 years or so, most homebuilders are now required (by law) to have a "95% compaction rate" (for foundations) in order to minimize "settling". This is probably why we see "good soil" (loam) in older neighborhoods compared to the "subsoil (clay)" soils we see nowadays in newer developments.

To me, these newer properties would benefit from organic matter --such as your products (good stuff), core aeration, additional water, etc to make lawns healthy & look nice.

Prob is, many of these customers are lazy......even if they have a sprinkler system, they're often too cheap to use it (yet they'll sign up for core aeration). Most just want to pay a lawn service to come out & "put stuff on" and expect their lawn to the nicest in the neighborhood. Go figure. Then too many will go out & mow/trim way too short. Life goes on. :laugh:

Yup Larry, without proper mowing & irrigation lawns are tough to maintain. It's up to us, the pros, to educate our clients. Now, anytime you need great fertilizers, just give me a call. :waving:

[greenskeeper44]

thanks for the link for some reason when i googled it a few months ago i found nothing? maybe i didnt look hard enough? but thanks again!

[Smallaxe]

Ok, here's my question, other than actual science, we were always told to use a "balanced" fertilizer 3:1:2 ratio usually. Then prices of materials start going sky high and in order to keep prices down for the customers (us from the fertilizer suppliers) they started ommiting the P out of the mix. Then K began to rise in price dramatically and now they are omitting it as well. At first everyone was mad because it was going to be bad for the lawns to be only applying N all the time... Then some started looking at the real science of it, and now we question why we were using the "balanced" fertilizers in the first place!

I too have had a few soil tests done, and same results here. P and K are generally "high to very high" in the soil. BUT... We know they are also generally "locked up" in the soil. Does this mean they aren't really available for plant uptake? If that's the case, then when we add some via fertilizer, is that being taken up by the plants or is it just going into the soil profile and adding to what's there already? If the plants aren't able to use what's in the soil because it's locked up, and they can use, and need, what we are adding with fertilizer, dosn't it make sence to continue adding it? Instead of soil samples shouldn't we be doing tissue sample testing to determine what the plants NEED, not what's in the soil. Or a combination of both and see what's there and what's needed, and if what the plants need is already there, finding a way to 'unlock' them in the soil.

A simpler way to put it is:

"Balanced in the soil, not in the Hopper... :)

[Smallaxe]

I have read this from many threads but I cant find any research to prove that statement. Do you have any?

ICT Bill was the one that had a whole bunch of stuff and I took those sites, and searched around, found other independant ideas, and it seems that "Botany/mycology", agrees with the precept"...

If I need to do a Search, myself, on Arbuscular Mychorhizzal Fungi, for you, I suppose I could... See what's out there... For me , it's a 'given',... but let me know... :)

[DA Quality Lawn & YS]

Thanks Barry. Makes sense.

Seems during the past 35 years or so, most homebuilders are now required (by law) to have a "95% compaction rate" (for foundations) in order to minimize "settling". This is probably why we see "good soil" (loam) in older neighborhoods compared to the "subsoil (clay)" soils we see nowadays in newer developments.

To me, these newer properties would benefit from organic matter --such as your products (good stuff), core aeration, additional water, etc to make lawns healthy & look nice.

Prob is, many of these customers are lazy......even if they have a sprinkler system, they're often too cheap to use it (yet they'll sign up for core aeration). Most just want to pay a lawn service to come out & "put stuff on" and expect their lawn to the nicest in the neighborhood. Go figure. Then too many will go out & mow/trim way too short. Life goes on. :laugh:

Yep Larry, my house sits on one of those new development, compacted clay lots. Lawn looked like crap 3 years ago. Started with a good fert program with aeration and topdressing. Looks MUCH better now.

[rcreech]

Kiril,

Glad we can agree on a few things!

Yes P and K can leach but as I stated very rarely in a lawn situation.

P is very immobile in the soil up to 300#/ac and soil loss (ie erosion) is the main loss
K is also very immobile unless a very low CEC or soil loss, which again is not common in a lawn situation.

Just wanted to clarify!

[Kiril]

Glad we can agree on a few things!

Imagine that. :dizzy:

Yes P and K can leach but as I stated very rarely in a lawn situation.

P is very immobile in the soil up to 300#/ac and soil loss (ie erosion) is the main loss
K is also very immobile unless a very low CEC or soil loss, which again is not common in a lawn situation.


P has been long considered immobile due to it's tendency to form insoluble precipitates. However some newer studies (links posted somewhere in this forum in the past) have shown it can and does leach into ground water. That said, erosion is probably the dominant form of loss you will see.

K on the other hand, can be easily leached depending on various factors (water, other ions, CEC, etc...). Say for example I were to foolishly apply gypsum because someone told me it could alleviate compaction. One of the possible results of this would be leaching of K. Same can be said for lime, irrigation water, or any other amendment/fert that has a high concentration of ion(s) that can displace K on the exchanger. The extent of leaching depends on the soil, however if you leach below the effective root zone, it is a loss.

[americanlawn]

DA Quality
Seems those clay soil lawns are the first to go dormant during drought. Sometimes I feel like hiring my brother to chop us some corn stalks & DISK them into some of these yards. Then follow up with a "honey wagon" full of you know what. :laugh:

[tlg]

The times are a changing. For years we used " balanced fertilizers " mostly because fert companies were selling " balanced fertilizers ". As an industry we all have become more knowledgeable in what we apply, where we apply and how we apply fertilizers. The science behind what we use and the economics of keeping our cost down are the two factors reflecting the elimination or reduced use of P and K. Cost reduction will probably be the biggest motivator IMO. As an industry we are all being held to a higher standard and accountability for any environmental implications. The bottom line here is applying less is more.



The clay soils around new home construction has always been a nightmare. All to often in these developments the " good soil " is stripped off and sold. It has always amazed me that this is allowed to happen. We have seen homeowners as well as landscape pros install lawns on top of poor soils with no soil test or soil amendments done. The biggest joke is the one or two inches of topsoil spread on top of the clay as a good medium for seeding or sodding. The time to fix the soil is before installing the lawn not after. It's no wonder these lawns surface root only, dry out faster and need more care in general. The only way this problem could be addressed would be through some sort of inspection program with a third party. There are no minimum standards to be adhered to and poor installs are done all the time. It would help the homeowners and the professionals they hire after the fact to maintain their landscapes.