Soil Compaction

KevinS

KevinS

Branched out member
Location
ontario
Hey guys

If you’re planting in a school yard or somewhere you know will be ridiculously compacted after you leave do you dig a bit deeper and go in with HPB or gravel or washed stone of any sort so that the roots can still move with some ease as the soil gets crushed?

And yes mulching to lessen the stampede effect, hoarding etc is an option but kids like to play with trees so I’m looking at root areas.

Thanks
 
Start with answering the most basic tree planting question, will the site work long-term? I find it so depressing to constantly see trees planted in locations that will limit their life to short, pathetic struggles. Sure kids like to play with trees, but even mature, well-established trees will be adversely affected if the volume of activity is higher than the biology can withstand.
Planting millions of trees sure makes us feel good but it is not doing any good for the trees or us if they don't survive.
 
Will any of the long term root area be out of the compaction zone? The problem with a structural soil (stone to keep it from getting compacted) is that where the volume of stone has displaced real soil, you are limiting how much soil the tree has access to and soil volume matters. If you are using it to provide a pathway to better soil, that may be a viable option. But if it is just to limit compaction in an already limited rooting space site, it may not help much. I think starting with good soil and covering it with slightly thicker mulch is the best bet there. Of course the crew that will be doing long-term maintenance needs to understand no volcanoes and don't let the mulch get too thick over time.

Are silvacells an option. They are expensive, but they work well...
 
Last edited:
I’m thinking school yard so a million little feet compacting for years. I’ve heard an argument for mixed size stones like field stones mixed with gravel size mixed and topped with soil. To make a more natural soil in the end. If site is prepped with a hole with radial trenched pinwheels going out with this mix it could give the longest run for root ease
 
ATH said:
Will any of the long term root area be out of the compaction zone? The problem with a structural soil (stone to keep it from getting compacted) is that where the volume of stone has displaced real soil, you are limiting how much soil the tree has access to and soil volume matters. If you are using it to provide a pathway to better soil, that may be a viable option. But if it is just to limit compaction in an already limited footing space site, it may not help much. I think starting with good soil and covering it with slightly thicker mulch is the best bet there. Of course the crew that will be doing long-term maintenance needs to understand no volcanoes and don't let the mulch get too thick over time.

Are silvacells an option. They are expensive, but they work well...
Click to expand...
Silvacells are a good option but as you mentioned more pricey than doable. Radial trenching can be done easy and quick with mini ex at dig time
 
But those trenches will recompact...unless filled with aggregate, which puts us back at limited soil volume. So unless they are leading to greener pastures for the roots, they will be cheaper but not terribly beneficial. I'd also be a little concerned about the trenches settling and being a trip hazard in the playground.
 
KevinS said:
I’m thinking school yard so a million little feet compacting for years...
Click to expand...

Given that a well-established, mature tree would decline under those conditions, how do you think a freshly planted tree will do?
Anything is possible given enough thought and money. That does not sound like your situation.
 
  • Like
Reactions: ATH
I would not try to stave off soil compaction - that is going to happen, has likely already happened, and will be hard/impossible to mitigate significantly. I know little about ammending soil to decrease *future* compaction, so kindly take my view with a grain of salt.

It seems that some tree species do better with compacted soils. I think you're probably already considering this.

Have you defined the nature of the compaction as a function of depth, and across the grade? I take measurements, tabulate them, and look for trends in order to get the most actionable information. It really isn't that much work for the information gained... Compaction has different causes (little feet, surface water runoff, history of large equipment, etc.). You may help yourself out quite a bit if you can define the nature of it and structure your planting around that information by moving the planting locations or by placing certain tree species in certain places. It's great that you're using some common sense here. Wish you success.
 
  • Like
Reactions: ATH
Just for conversation. What is everyone’s thought of doing the above with large hog fuel, screened to big chunks. It would meet the short term goal of skeletal soils, break down at a much slower rate if buried, and break down increasing the OM. Long term some settling would take place but I see this effect in the forest all the time with large woody material.
 
These days, it would seem unlikely that a school would let the kids actually climb in the trees, so the major benefit is going to be the canopy... the trees themselves could be planted in limited access zones that protect the root soil from compaction, but this is an option for playground landscape design prior to construction... a little harder to do as a retrofit if the available space is limited or the playground is surrounded by parking lots (not unusual). A low, but very sturdy fence between the landscape zone and the playground area is a good psychological barrier, but you must have the expectation that the kids will climb on the fence itself, and it should be constructed accordingly. The landscape zones provide some seclusion, a healthy atmosphere and noise buffering when they form a perimeter around the playground.

For that model, shrubs and other landscape plantings fill a big chunk of the root zone of the trees, and this eats up a considerable amount of space. It's also a fairly big undertaking, so might be well beyond what you're envisioning.

I've seen many examples of the "plop some trees in the playground" approach. I can't think of a single one that was even remotely sucessful. A few years later, it seems they all end up back to a barren, depressing area that resembles a prison excercise yard more than a happy place for kids.
 
  • Like
Reactions: ATH
It’s not climbing that’s an issue. It’s the compacted soil and the worn spot where they grab it and spinning in circles around and around
 
Damn kids. Mine goes to a out door based school in a old growth forest, where the kids voted to stop climbing the maple when they realized the bark was getting damaged.

Cage the kids in the playground and let the trees have the field.

A fence sounds like a good idea, and it might be a good spot for a large planting with lower limbs out of reach. How about working with the kids on the project? Have a assembly, take groups of kids out to dig, stretch roots, mulch, water, and teach them how to look after and care for the tree. Make it their pet nd make them in charge.
 
In 2006 I witnessed a 30 ft. tall tree disassembled by college students rioting after a national championship football win. It was like ants on a grasshopper.
 
There are a few unanswered questions, what tree are you planting? What type of soil is native to the area? because when the tre matures the drip line will be in native soil. What age are the students? Ring around the posey age? What caliper tree do you intend to plant? Will the tree have steady access to water? Can the tree have a barrier erected like snow fence to keep monkeys off it? If you can control these factors then you should be able to plant the tree and brace it like any other tree. If it survives, then it was meant to be.
 
  • Like
Reactions: ATH
You must log in or register to reply here.

New threads New posts

Back
Top Bottom