Many tree roots above the ground surface are steadily destroying our mowing equipment. Research has shown that the roots are seeking oxygen. Who knew that an oxygen producing organism needs oxygen well, at least on the other end. The root system demands it and will literally climb out of the ground. So, it seems aside from obvious erosion that compacted soil and too much water lingering around the roots are the culprits. In our case we have extremely packable clay. Even after added "loosening" materials to our vegetable garden for years we have severe packing after a couple of hard rains. I need ideas to rejuvenate the oxygen around the trees. Most Arborists discourage cutting the exposed roots and they say backfilling is not the answer. So, aside from installing oxygen generators on all the trees I struggling with options between saving our trees and equipment. Besides, I'm not sure where to connect the nasal cannula for the Oxygen. Thanks for any ideas BKP
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1Welcome Brian. Whilst we can give you the answer regarding the mechanisms involved within the plant, we're not in a position to give expert gardening tips. There's a dedicated Gardening & Landscaping site on the network that you might check-out. Please ensure to take their tour and refer to their help centre before you post to ensure your question is on-topic and in-shape.– Jiminy Cricket.Commented Jul 2 at 11:57
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If you're in a temperate region, I'm guessing that you have either a Norway Maple or a Silver Maple, as those two species are notorious for having high roots.– JurpCommented Jul 2 at 20:45
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Hi Brian, in line with Jurp's comments we need to know more: what part of the world, what kind of trees, just more detail...– kevinskio ♦Commented Jul 2 at 21:19
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The question is probably too generic. Which tree and where? Water hinder O2 exchange, so mainly trees on aquatic environment may have special organ on roots for that. Else active soil should be able to provide enough O2. OTOH specific species may be hardwired for their original soil/environment. We need more info.– Giacomo CatenazziCommented Jul 3 at 7:10
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Remove the grass near the tree, mulch, and stop mowing too close to the tree. And don't discount "obvious erosion" which you breeze right by on the way to "roots climbing out of the ground" - when the ground erodes and root stays put, it sticks up more, without climbing at all.– EcnerwalCommented Jul 4 at 1:07
2 Answers
The actual oxygen exchange is happening at the root hairs, not the entire body of the root. Any root substantial enough to interrupt your mowing is structural, supporting fine root hairs further down.
Just as you said, the main factors impacting how deep that oxygen can penetrate are soil porosity and moisture content. This study gives us some numbers to put a scale on it. The test cylinders were 42cm (16.5in) deep.
The study notes 0.2μgm cm2/min as a general cutoff for sustaining root growth, so the table shows us that even in their most compacted soil adequate oxygen was penetrating down about 6 inches of 'uncompacted' soil and 2 inches of 'compacted' soil.
So to help your trees get more oxygen, you need to improve the aeration and drainage of the soil the trees are growing in. Easier said than done! One easy way to do this would be to raise the grade around the trees gradually enough that their roots can grow up towards the new surface before you add more. That way you would cover those exposed roots and also create 'well breathing' soil at the surface for the tree's root hairs to grow into.
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Related papers that get into the fun of soil diffusion: scielo.cl/…. people.ucsc.edu/~wxcheng/envs161/PDFs_supplemental/…– MackMCommented Jul 2 at 22:33
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SO, top dressing twice a year with a half inch to inch of compost or soil?– kevinskio ♦Commented Jul 3 at 1:42
Maybe you could try a broadfork to aerate the soil. They're supposed to be able to work for that purpose, among others.
Some narrow deep holes in the ground probably wouldn't hurt the plant, either.