Mulch that root zone

The roots of trees extend radially away from the trunk as much as 4 times the height of the canopy.  What! Does that mean a 20 foot tree has a mass of roots as far as 80 feet away?  Yes.  Well, of course that depends on a few things but generally speaking, that's correct.
Whats more, those roots that extend farthest away from the tree have a massive surface area relative to the anchorage roots closer to the stem.  The great number of root hairs associated with the finer ends of the roots system are thin and therefore extremely efficient at absorbing minerals, oxygen and water.  By the way, 80 to 90 percent of the roots of a tree are located in the top foot to 18 inches of soil. Not a mirror image of the tree canopy.  Thus the common term "root plate."
Check out the root system of the wind-thrown tree below.

Another interesting thing to know; roots form beneficial relationships with native soil fungi.  The roots spill nutrients into the surrounding soil and the fungi absorb and use them for growth and development.  In return, the fungi attach themselves to the root system and increase the absorptive surface area of the roots, allowing the roots to take up even more minerals for the tree. Cool stuff huh?  Well, some companies make and sell soil fungi, known as mycorrhizae, for mixing into the soil root zone with the belief that it will make your trees healthier and able to withstand adverse conditions.

Ok, so I stole a picture from Wiki, but it was the best example I could find of mycorrhizae on short notice.


I have an idea!  If most soils naturally contain some type of mycorrhizae, why not just improve the soil conditions of the roots zone to aid in the development of the fungi.  In fact, that's exactly what happens under a 4 inch layer of organic mulch.
The soil, or dirt if you prefer, under a thick layer of wood chips stays cooler and moister for longer periods than bare soil or soil covered by pebbles, rubber tires, or other inorganic mulches. Studies have also shown that, over time, the ability of soil to hold minerals and oxygen is improved under natural mulches.  Of course they need to be "fluffed" occasionally to avoid having a water-tight mat form over the roots, but that only takes a few minutes per year.  Organic mulches will even break down and provide some minerals to the roots, so when its time to replenish the decomposing mulch, simply stick a pitch fork into the existing layers, twist it back and forth a few times, then add the new mulch right on top.  This is what it should look like:

Yep, that's grass growing right through the mulch.  No need to kill the grass first, just mow it down and throw the mulch on top.  Notice that this bed of mulch extends all the way to the edge of the tree canopy and beyond.  It does little good to extend the mulch only a few feet away form the trunk since the most efficient roots are much further away.  If the grass annoys you, spray it with glyphosate, aka RoundUp.  Glyphosate is not active in the soil, therefore it wont get into the root system through the dirt.  It must contact something green on the plant in order to effectively kill it.  So spray the grass leaves and don't allow the chemical to drift onto the trunk or in the canopy.  Actually, if it gets onto the trunk, it probably wont do any harm but if it were my tree, I'd avoid letting it hit the trunk.