Good Soil Makes Good Tree Care

“90% of all tree problems start at the soil.” 

Dr.  Lindsey Purcell, Board Certified Master Arborist with 40+ years in in urban forestry. 


The greatest threat to our urban tree care isn’t up in the canopy but down in the soil.  

The soil is where all the nutrients get absorbed that get carried off to the rest of the tree.  The problem is that soil health in the urban environment is typically poor.  

Good soil, such as what is found in a forest, is spongy.  Walk through the forest and you will feel it underfoot. 

Good soil allows water, air, nutrients and roots to flow freely underground. 





Most urban soil suppresses this movement.  Urban soil often squeezes out the development of this underground network, in favour of above ground networks of roads, walkways, and buildings.  Rather than urban soil acting as it should, like a sponge, it is more akin to a brick.  Trees oftentimes find it quite difficult to absorb anything of value from the soil around it.  

This squeezing out of the underground soil network is referred to as soil compaction.  



Effects of Soil Compaction

There are 2 primary ways you can reduce soil compaction:

1) Expand the area where mulched is applied under a tree.

As the mulch decomposes it will break up some of that compaction.  It will also create an above ground buffer which acts like a spring to prevent the soil from experiencing the full impact from the sources of compaction, namely machinery and frequent foot traffic. 

In the ideal world the area mulched under a tree would extend out as far as the branch tips or even further.   This option isn’t always practical as oftentimes there simply isn’t enough space to do so. There usually are too many obstacles competing with where mulch can go from sheds to patios to driveways to fences.

Which leads to another option…

2) Air Spading

Air spading involves the use of high pressure air focused directly into the soil, in line with all the primary roots of the tree.  When performed in multiple locations under the trees canopy it fractures the soil allowing for air and water to circulate better.  Air spading is opening up the underground network to provide more room for the exchange of nutrients between the soil and the rest of the tree.  



air spading for soil health of trees

The benefits of air spading:

  • Amends the soil without the use of any chemicals.
  • Reduces watering needs by improving the ability for roots to absorb water.
  • It is non-invasive.  Strong enough to move the soil but not to damage living tissue.

If you aren’t sure if you have soil compaction issues you can reach out to a Certified Arborist to accurately test it.   

Want to test it yourself?   Get a pointed spade shovel and hold it up so that the tip is touching the soil.  Step on it with all your weight.  If the spade doesn’t break the surface or barely breaks it, there is a very high chance that your soil is too compact.

 If you want to go one step further to caring for your trees after air spading then we recommend amending the soil with compost following the air spading.

Looking for more help in this area?  Give us a call or fill out the form below.



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