Surface roots a lawnmowing problem

[randym85]

I mow the lawn at my wife's office... the lawn surrounds two black locust trees whose diameters are 12-14". There are now roots from both that are growing very near the surface that are year by year becoming more of problem for my mower to go over with out hitting and presumably damaging the blades. I dug down on one such root to see how big it was and to my surprize it is 6-7" in diameter!!! I thought an 1-3" root was all I had to deal with, but the size of this makes me concerned that if I cut it (and leave it to rot?) that I will severly damage the tree. Can I proceed with this plan or will I damage or kill the tree, is there a better time to do it if I can proceed, any other precautions ... solutions I should consider as I have two trees to deal with and several roots each (perhaps cutting one sizable root a year?)

 

[Sheshovel]

I would not recommend cutting any roots but instead putting down a neat mulch around the tree where the roots are and forget about mowing or growing grass over them.

 

[Ekka]

I would not recommend cutting any roots but instead putting down a neat mulch around the tree where the roots are and forget about mowing or growing grass over them.

Aye Aye captain, and that way you'll kill a whole flock of birds with one stone ... the most important being less lawn to mow and more time to do something else ... isn't there a game on right now somewhere on cable?

 

[treeseer]

Yes please do not damage that wonderful mower. Consider adding porous topsoil between these roots and installing a groundcover that you don't need to mow. Vinca, Liriope, etc.

Then mulch as per the above recommendations, and the info in the link below.

 

[TreesnHorses]

Agree with everyone here, Randy. If you mulch be careful not to overdue it; a thin covering to make it look neat is all you need, and keep it away from the base of the tree. That said, I don't know what your situation is, but I have seen many times where roots are EVERYWHERE in a yard, and the poor people would have to mulch their whole yard to take care of that problem! At the very least, raise the mower blade up if the whole yard is an issue, and mark the big roots so you don't run them over and bend the shaft on your mower. ;-)

 

[Kneejerk Bombas]

I would not be totally opposed to just adding soil nice loamy soil to the surface to cover the roots, provided that it didn't exceed 1 or 2 inches in depth, although the chip bed idea sounds better. And if it will take more than an inch or two, adding the soil a little bit each year, might allow you to raise the grade with little stress to the tree, because the tree will send roots up into the new soil.
So if you need 4" to cover the roots, add a couple this year and a couple more in a year or two. Just adding 4 inches in one shot would be a very high health risk for the tree.

 

[treeseer]

Just adding 4 inches in one shot would be a very high health risk for the tree.

IF the soil is porous, on a 12" Robinia pseudoacacia, adding 3" soil and 3" mulch to get the grad up to the top of the roots should be ok. Pictures would help a lot; Mike and I can argue much better with visuals. :Eye:

 

[Ekka]

I found video better than pics to argue with him Treeseer!

 

[Kneejerk Bombas]

Every thing I say is right, so arguing with me is a waste of time either way.

 

[Kneejerk Bombas]

IF the soil is porous, on a 12" Robinia pseudoacacia, adding 3" soil and 3" mulch to get the grad up to the top of the roots should be ok. Pictures would help a lot; Mike and I can argue much better with visuals. :Eye:

Soil gas exchange is important part of why adding soil or mulch to the top of roots can be harmful. Roots need oxygen, which is replaced after rainfall because each little pore of space in the soil is filled with water, which pumps out the toxic gases and then as it percolates down or is pulled into roots, brings in a fresh batch of air.
Soil oxygen levels are why roots tend to grow close to the surface.
If the soil or mulch is very porous, the soil gas exchange can happen with just wind. if the soil pores are large, but too small for wind to accomplish the exchange, the oxygen levels can drop off significantly, because rather than pumping the soil gases, rainfall just runs through the large pores and doesn't move the gas.
A good example of this is compost. As great as compost is for plants, pure compost is a lousy growing medium because it doesn't support high oxygen levels.
This is why it's so important not to mulch too deeply, percolating water does almost nothing in terms of soil gas exchange in course mediums like wood chips, and at the same time the decaying chip produce large amounts of CO2 and other toxic gases.
All this is unimportant, other than to spend a minute arguing with Guy, yet again.

 

[treeseer]

Soil oxygen levels are why roots tend to grow close to the surface.

As usual I agree with Mike. :angel: Before adding soil or mulch I typically swing a pick into the ground to fracture the soil and get the O2 down there. That also leaves channels for the nutrients to work their way down faster.

A primary fact is that if leaves are raked, the tree has had its own nutrient cycle broken and its root system is eroded. Turf competition adds to the problem. They must be replaced; the trees want their leaves back!

 

[Sheshovel]

IF the soil is porous, on a 12" Robinia pseudoacacia, adding 3" soil and 3" mulch to get the grad up to the top of the roots should be ok. Pictures would help a lot; Mike and I can argue much better with visuals. :Eye:

This advice is not well advised.
A total of 6'' added to the surface under any tree would be detrimental.
1st you disagree with Mike then you agree,I just agree.
But one thing we all agree on is do not cut the roots

 

[Ekka]

Every thing I say is right, so arguing with me is a waste of time either way.

 

[treeseer]

A total of 6'' added to the surface under any tree would be detrimental.

And what facts, research or direct experience is this statement based on? Many stressed, eroded urban trees that got 6-12" of mulch straight out of the chipper box have thrived (Bioremediation study of live oaks at LSU campus).

If you got data, we can duel.

If you got dogma, there's not much to talk about.

 

[Ekka]

If you got data, we can duel.

If you got dogma, there's not much to talk about.

He thinks he's always right too, so be careful around this town.

There's a few more too, you'll get to know them.

What about those trees which like to be fully submerged around the root system, they have pneumatophores to overcome the anaerobic problems! I wouldn't mulch them.

 

[rebelman]

What they said. Mulch it. You can fracture the soil with a pick. Put composted mulch down. Add a little diversity: manure, peat, pine bark, hell tomato juice, or piss. Border it symmetrically to the dripline, is is bermuda grass? This adds maintenance needs. Nine five percent of my clients ignore this advice, even after repeatedly telling me they want to help the trees. I give them the yadda yadda finger puppet motions and they still hire me! Lawn mowing is an easily reduced source of consumption and pollution. Organic and inorganic mulch provides instant and longterm stress relief for trees, retains water, moderates temperatures,slows erosion, provides trace elements, etc... the benefits are little understood and greatly unappreciated. Even asthetics are greatly improved, features pleasing to the eye. I could go on, but I'll just stop now.

 

[wysiwyg]

This topic has always seemed like a contradiction to me. If a tree's main source of energy is through photosynthesis, in which CO2 is taken in and O2 is given off as waste, why do the roots need O2 for the tree to survive?

 

[pinus]

Im not specialist in this field. But we can think in the way...leaves are geting sunlight which is the main energy source for their living, also they are producing all the needed and redundant oxygen. Roots are not geting light, their energy source is some compounds received from leaves, but some processes are needing free oxygen to go also. Oxygen is extracted from the soil

 

[treeseer]

Roots are not geting light, but some processes are needing free oxygen to go also. Oxygen is extracted from the soil

pinus is exactly right; I swear s/he's closer to 100% than anyone here! rebelman's on point too, but I'm not so sure about the tomato juice.

Roots have living cells. All living cells need oxygen to respire and live, some much more than others. If you get more oxygen deeper into the soil, you will get more roots there and less on the surface.

see Proper Mulching Techniques in the link below.

 

[Sheshovel]

SURFACE ROOTS




SURFACE ROOTS:
Contrary to what you might think, Tree roots are not coming to get you ! Roots, by design are simply trying to seek out, gather and control resources in the soil. When you see roots growing near the surface, there are reasons for this growth.
And You should understand what these reasons are


Is this the Natural root system of these Trees ?
Maples, Tulip, Locust, for example

Determine Why to ensure Tree’s successful growth & vitality

When growing conditions are not conducive to health, Roots will grow where they find the resources they need to thrive
As long as roots have oxygen, they will continue to grow and seek soil resources, including water. Because of the ease that roots pull water from the soil, roots sense and grow toward areas where water is available
The Quandary is - water supplies must be in the same soil where atmospheric oxygen is available. Soil organisms quickly use the dissolved oxygen in soil water and it is not then readily available to tree roots as atmospheric soil oxygen
Atmospheric oxygen is essential to tree life
The above ground portion of the tree finds oxygen in the air for respiration ( Oxygen content in the atmosphere is about 21 % )
Green tissues use oxygen for respiration when photosynthesis is not working. However, for unrestricted root growth, the soil must contain more than 15 % oxygen
If soil-oxygen levels fall below 5 % - all root growth STOPS
Oxygen levels below 2 % cause root decline and tree death

Major causes of inadequate soil oxygen are:
Competing organisms
Soil compaction
Water-filled pores (saturation from flooding)
These Oxygen-limiting problems of the soil are called

Anaerobic Conditions
Adding additional soil, even a few inches, over existing surface,
Puts the major root mass that much deeper
With less oxygen the roots die quickly
Unless new roots ( tertiary roots, rootlets ) can be rapidly produced in the new surface soil,
The Tree will then die also

Soil compaction has a similar effect
Reduces air supply to the soil
Creates a physical barrier to new root growth


Areas that receive continuous foot / vehicle traffic are prone to this problem.
SEVERED / DAMAGED ROOTS:
Construction or Landscaping activities that cut the roots of Mature trees will often lead to the death of the TOP portion or all of the tree
This may take up to TWO YEARS or more to appear
Commonly, Long after the injury happened and has been forgotten

Keep in mind that tree roots do not respect property lines
Activities in your yard may effect your neighbors' trees, and vice versa.
Changing Soil Aeration is by far the Most Common and Serious root injury we inflict on Mature trees

The BEST solution for surface roots is to select the CORRECT / PROPER Trees and plants for that location

Choosing the Correct Tree See NEW TREES
POSSIBLE ALTERNATIVES :
If you already have a large old tree with surface roots that you don't want to lose, you may just have to learn to accept this intrusion
Perhaps a compromise is best ..........
Plant something that requires NO Mowing
Consider planting ground covers, annuals, etc.
Disguise the roots, prevent tripping, damaging equipment
If feasible, Mulch the area
The use of Mulch has been proven to be the MOST beneficial element to continued health of Mature trees ( ie: the forest floor )
MULCH will help to 'stabilize' your plants' environment
It retains moisture and helps to 'insulate' and 'regulate' the soil temperature

LEARN MORE ABOUT ROOTS and MULCHING

See the ABOUT ROOTS & MULCH Pages



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