# Soil analysis results & recommendations



## coolbrze (Dec 10, 2015)

We just did a soil analysis on a clients property (2 attachments). Can you tell me what their trees (predominately a mature Chestnut Oak) need? Any help is greatly appreciated, thanks!


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## ATH (Dec 10, 2015)

Look under the area labeled "Customized Rate Recommendations". Specifically under the early spring recommendations.


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## Dbodave (Dec 11, 2015)

Soil ph 5.4 wow! it's 7-7.5 where I live. I've only ever used Davey arbor green pro 30-10-7, 20 of N is microbial release and lasts 1 year plus


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## Dbodave (Dec 11, 2015)

Davey arbor green pro 30-0-10 if your phosphates high.


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## macattack_ga (Dec 11, 2015)

lime


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## ATH (Dec 11, 2015)

I wouldn't get too excited about that pH with Q. prinus.


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## Dbodave (Dec 14, 2015)

I didn't think about that, opposite problem than I get here.


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## coolbrze (Dec 23, 2015)

I'm no expert but it is my understanding that what may be good for the turf isn't necessarily good for the trees. That's why I was asking & didn't go off Shemins rate recommendations as those are catered the lawn vice trees. Still not sure what to tell them...


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## Dbodave (Dec 23, 2015)

I admit I'm a noob with soil analysis. If you look at the ph chart I posted above you will see that your ph 5.4 is limiting the availability of the 3 main macronutrients NPK, as well as a few micronutrients. Someone said lime to buffer soil and raise ph, and someone said a high N fert, those would both be beneficial to the health of the tree. I recommend a slow release fertilizer for trees that have a sustained 1 year feeding. Lawn ferts are short lasting which is why lawn co's do several apps per year.
How did the tree health look? Is it chlorotic? Is there adequate space for root growth? mulch? Those are the things I look at. Generally a nitrogen fertilizer can help the tree develop a thicker root system, which helps them compete with turf roots. It can help smaller trees grow and establish quicker especially when grown in turf. Mature trees on the other hand are not going to grow faster from it but still benefit from an annual or every other year fert.


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## ATH (Dec 23, 2015)

coolbrze said:


> I'm no expert but it is my understanding that what may be good for the turf isn't necessarily good for the trees. That's why I was asking & didn't go off Shemins rate recommendations as those are catered the lawn vice trees. Still not sure what to tell them...


Use a lab that gives reports specific to your tree species.


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## ATH (Dec 23, 2015)

Dbodave said:


> I admit I'm a noob with soil analysis. If you look at the ph chart I posted above you will see that your ph 5.4 is limiting the availability of the 3 main macronutrients NPK, as well as a few micronutrients. Someone said lime to buffer soil and raise ph, and someone said a high N fert, those would both be beneficial to the health of the tree. I recommend a slow release fertilizer for trees that have a sustained 1 year feeding. Lawn ferts are short lasting which is why lawn co's do several apps per year.
> How did the tree health look? Is it chlorotic? Is there adequate space for root growth? mulch? Those are the things I look at. Generally a nitrogen fertilizer can help the tree develop a thicker root system, which helps them compete with turf roots. It can help smaller trees grow and establish quicker especially when grown in turf. Mature trees on the other hand are not going to grow faster from it but still benefit from an annual or every other year fert.


That pH isn't terrible for the species...Other species would be in bad shape with a pH that low. Raising it a little could help, but that is not as big a concern as some of the nutrients.

Nitrogen does not encourage root development...it increases top growth at the cost of improved root growth. Potassium is the glaring need on that test. A tissue sample next spring would clarify some needs as well.


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## Dbodave (Dec 28, 2015)

ATH you should look at this study concerning fertilization and root development. 
http://joa.isa-arbor.com/request.asp?JournalID=1&ArticleID=2594&Type=2

Study 2. A second study was undertaken to verify the root growth differences associated with the balanced fertilizer and to investigate which nutrients were responsible for the increase in root density. More detailed sampling over a broader area provided more information on how far from the treatment hole the fertilizer influences roots growth. Nitrogen was the only element that was consistently associated with significant increases in root development (Table 2). Potassium-, phosphorous- and vermiculite-filled holes showed no increase (data not presented)


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## ATH (Dec 28, 2015)

Thanks for the link! I hadn't seen that before. Presents some possibilities. Will have to ponder it more and would like to remain in dialogue. So this isn't to argue....just what I can see so far:

1) opening paragraph of that publication: "Excess nitrogen fertilization can reduce fine root formation". So unless you know what is there, you can't know what is "excess" or if you are filling a need.
2) last paragraph: "Though the addition of nitrogen fertilizer increases root density near the point of application, this may may not represent an increase in total root mass. One report suggests that root development in other parts of root system may be reduced..."
3) This study did not look at total plant growth. Let's say just for an example that they did in fact find that total root mass increased by 5% with N fertilization over the control. What did the rest of the plant do? If top growth was 10% more in the fertilized plants then wouldn't it suggest that the root growth did not keep pace with the top growth? Among other results this study (fixed link) found that root mass to total plant mass decreases. So I think the bottom line according to that limited amount of data is that (as I understand it to mean) N increases top growth at the cost of root growth...
3a) Perhaps more significant, is that N fertilization costs the plant defense compounds. That is covered in the above article, but is easier to get through in this presentation.


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## Dbodave (Dec 28, 2015)

Sounds good, the first link you posted didn't work. The second looks interesting (I saved the pdf), but I never claimed fertilization could increase pest resistance. It's a bit unsettling to hear that excess fertilization could make a tree more susceptible to pest problems. Out of all the paper birch we have fertilized over the years, I've only had one begin to show branch tip die back, likely BBB damage. Normally we don't get called until after they are showing symptoms and we've had excellent recovery with insecticide treatments plus fert for maintenance. Additionally I always tell homeowners that watering is the best thing they can do themselves to maintain health and minimize stress. We never fertilize pines with diplodia blight.

Back to point 1. "Excess nitrogen fertilization can reduce fine root formation" obviously over fertilizing with a high salt index, inorganic fertilizer will damage roots. Organic fertilizers or slow release fertilizer with a low salt index will not damage roots, additionally they rely on microbial activity and release N close to the same rates as organic.

"So unless you know what is there, you can't know what is 'excess' or if you are filling a need" True, but what I do know is the urban environment is much different than the forest environment that trees are adapted to. The topsoil is stripped away from home builders; leaving only a thin organic layer over subsoil, which is clay in most of our area. Trees are planted in turf, who's dense roots and rhizomes out compete tree roots in the upper layer where oxygen content is greatest. Trees have noticeably thinner leaf canopies, slower rates of growth and higher mortality in these conditions. This is a good read- http://www.extension.umn.edu/garden/landscaping/implement/trees_turf.html

I know alot of arborists have different views on the subject of fertilization. I don't think they necessarily need it, but feel it benefits urban trees.


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## Dbodave (Dec 28, 2015)

I also want to add that fert especially benefits small-medium size trees in the rapid growth phase. Large mature trees in the slow growth phase don't really get the increased growth from it, or it's so small it's really hard to tell.


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## ATH (Dec 28, 2015)

I think I got the link fixed.

Sorry - didn't mean to imply you said anything about pest resistance...I just mentioned because that was the focuse of Herms' study. The root:crown ratio was secondary observation. I should also mention even he doesn't claim to know that those results translate to larger trees in the landscape...while it is plausable, I have heard hom say he just knows what he found in a very controlled study with 2 species.

I agree 100% that our built landscape is suffering from poor to bad soil. I also agree that a good fertilization program CAN help trees thrive. My post was responding to the recommendation for high N (which I see I inadvertently endorsed when I said look at the lab recommendations). There is an place for that, but it has to be balanced with the whole picture. Based only on that soil test, is that the best prescription here? I think there are other glaring needs...including a late spring test of the foliage.


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## ATH (Dec 28, 2015)

Dbodave said:


> .....
> 
> Back to point 1. "Excess nitrogen fertilization can reduce fine root formation" obviously over fertilizing with a high salt index, inorganic fertilizer will damage roots. Organic fertilizers or slow release fertilizer with a low salt index will not damage roots, additionally they rely on microbial activity and release N close to the same rates as organic.
> ...


Probably correct...but I am not sure that the paper concluded salt index was the reason for that decreased root growth. It didn't mention root damage-just decreased formation of fine roots. Does that mean they are damaged or that fewer are grown???

Frankly, there is a knowledge gap because this is longterm and expensive research so there is not a lot of it out there. We can theorize (and I think you posted good facts that lead to a reasonable theory here regarding the comment about fewer fine roots) but until somebody does a controlled experiment, we really can't claim to know with certainty the reasons.

We can observe consistent results. N fertilization fairly consistently makes a tree's crown fuller and more green. One question is whether there are other "costs" associated with that even once you have settled on the right form of N??? Are those costs "worth it" in the long term???


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## Dbodave (Dec 29, 2015)

Thanks for that, that's a good question about fert "is there a trade off?" I didn't think of it like that, but I know the question will come up. The only trees I know of that have been treated consistently and watched long term are heritage trees that cities and universities have gone all out to maintain and preserve. I know of a couple, but couldn't find any info about them, I've seen articles somewhere.

The first link you posted was pretty hard to get through, but I got a few things from it. They did mention after trees acclimated to higher nutrient conditions that growth rate and secondary metabolic functions balanced out again. 

I stumbled onto another study by Dan Herms that's similar, Soil Ecology and Tree Health
http://www.oardc.ohio-state.edu/her...f_urban_forests_and_ornamental_landscapes.pdf


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## ATH (Dec 29, 2015)

Good find on that presentation!


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