Think for a moment, how long can one hold their breath? When one thinks of the compaction of the LIVING SOIL [A], this question must be considered. Roots must respire, i.e., burn glucose to release energy. Oxygen is a major requirement for this process . The mycorrhizae [M] are aerobic microorganisms which mean they require free, gaseous oxygen [O2] for their growth. A person could live for days or weeks without water or food, but I know of no person who can live very long without oxygen. Learning th e type of soil where a tree species grows naturally [B] is best and then plant these trees where the soil is similar.
The main reason soil compaction is so very injurious to the tree system is not because of the oxygen. Sure the oxygen is very important, the reason soil compaction is so bad is that it KILLS THE MYCORRHIZAE. At this point the tree begins to suffer from a lack of WATER & ELEMENTS and then the tree begins to have a micro element deficiency. Long before soil compaction shows as a water problem, we will see compaction show its face as a micro element deficiency.
Another word I need to mention is HYPHAE [H]. The hyphae are the vegetative parts of the fungus part of the mycorrhizae, and they are multicellular tubes. Just know that they are strands and they connect. One block of living soil with mycorrhizae and hyphae may give us a thousand miles of absorption, i.e., one square inch of soil. Take that one square inch of healthy living soil and multiply that and think about the millions that could be there about your trees. Now compact that living soil and wha t we have done is decreased the absorbing capacity by 1000 miles per each square inch of soil. We call this disruption leading to disfunction and depletion or the parts and processes of the tree system. How can we fix this problem, tear up the lawn? N O, place the mulch on top of the grass on top of the compacted soil. We have seen composted materials reduce soil compaction when applied properly. How then do we get the mycorrhizae back? By proper mulching! How much mulch is to much? If the roots a re growing into the mulch, we have too much mulch. PLEASE NOTE: We have fact sheets available on proper mulching (learn how to avoid attracting undesirables).
Studies at the University of Georgia, USA (1991) shows that if we walk over the same area (un-mulched!) 27 times we can compact that living soil to its maximum capacity. Something to think about.
[J] is the actual size of a mycorrhiza.
Diagrams from The Desk of John A. Keslick Jr.
Call us for other FACT SHEETS on pruning and other tree care information.
John A. Keslick Jr.
Tree Biologist
Contact
Text & Graphics Copyright © 1997 Keslick & Son Modern Arboriculture