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Posts Tagged ‘decompaction’

…and go back to school for a day.  If anyone in the Massachusetts woody-plants world has not seen the latest in tree- and shrub-planting techniques, here’s your chance:  on September 27, Rolf Briggs and Matt Foti will be giving a workshop entitled At The Root:  Air Tools Workshop at the New England Wild Flower Society’s Garden In The Woods.   Matt and Rolf will discuss and show the best techniques for planting trees and shrubs fresh from the nursery (air tools not necessary for this), as well as how to use air tools to trench under trees, decompact soil, and transplant trees.

I have my reasons to promote this workshop (and it’s next-day partner, At The Root: Understanding and Managing Healthy Soils), and they center on the fact that every planting season I find myself coaching laborers on how to deal with the root balls of plants that we’re planting on my job sites.  The boss, not knowing or having taught his laborers the proper planting techniques, usually has priced the work based on a quick  installation (dig the hole, stick the plant in, cover up the root ball, basket, and burlap), and the laborers, knowing only the quick and dirty method, look sideways at me as I show them what I want them to do.  The guys do the work the way I want it, but really, the process would go much more smoothly, and more landscapes would establish and grow in better, if everyone knew , priced, and carried out the work in what are considered the most plant-friendly ways.

Some of the most effective tools available to see what can be considered plant-friendly, and to work in soil crowded with roots, are pneumatic air tools.  I believe that Rolf and Matt will be transplanting a tree bare-root, using air, which will afford workshop attendees a chance to see what a tree’s roots really look like when the soil is blown away.  It’s an experience that can change how anyone working with plants understands how a plant grows and anchors itself, and for that alone this workshop is worth attending.

Watering in a newly planted tree-form Taxus from Weston Nurseries.

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Dave Leonard from Lexington, KY, manned the root forensics station at the September 10 MAA air-tool workshop at Elm Bank.  He used an Air Knife to excavate the root ball of a 4″ caliper red maple that was showing signs of decline.

Turf provided the only competition for this tree, but it was showing dieback and early fall color at the MAA workshop.

Turf provided the only competition for this tree, but it was showing dieback and early fall color at the MAA workshop. Dave Leonard excavated at its base to take a look at its rooting habit for possible problems.

With soil blown away from the original root ball, it was clear that the tree’s planting had initiated some problems — parts of the wire basket appeared at the edges of the root ball, and cut root ends had sent out an explosion of fibrous roots that turned back toward the trunk.

Root ends cut during the tree's digging in the nursery sent out masses of fibrous roots, quite a few of which turned back toward the trunk.  The interface between root ball soil and surrounding soil can inhibit root growth into the surrounding soil; removing burlap, removing the wire basket, and breaking up the root ball soil, particularly at the ball's perimeter, can help promote the spread of new roots.

Root ends cut during the tree's digging in the nursery sent out masses of fibrous roots, quite a few of which turned back toward the trunk. The interface between root ball soil and surrounding soil can inhibit root growth into the surrounding soil; removing burlap, removing the wire basket, and breaking up the root ball soil, particularly at the ball's perimeter, can help promote the spread of new roots. Note the soil line some inches up the trunk flare; removing soil above the trunk flare will also benefit the tree and lessen its stress.

Dave cut away the roots that he could not redirect outward, and trimmed off the roots that had begun to circle the trunk flare’s base, which would otherwise eventually girdle the trunk and major anchor roots.  Some of these roots were the beginnings of a secondary root system put out by the tree in response to its stress.

Removing the worst of the inward-growing and circling roots improves the tree's chances for survival.

Removing the worst of the inward-growing and circling roots improves the tree's chances for survival.

After excavating the root ball, Dave intended to continue to blow soil out away from the root ball, creating a shallow crater  out at least to the tree’s dripline.  Removing turf from that zone would eliminate plant competition for soil moisture; the addition of 2-4″ of mulch (kept away from the trunk) would help the soil retain moisture and an even temperature, add organics to it over time, and lessen the chance of soil compaction that inhibits soil/air gas exchange.

Dave said that he would also consider lifting the tree a few inches, to bring its trunk flare into a better relationship with surrounding grade.  This tree had been in the ground for a couple of years; Dave suggested that tree lifting might be worth doing within two to four years of planting, but could be detrimental to the tree after that.  (The window of opportunity for lifting a tree would be a lot wider if an air tool were used, rather than a Bobcat or excavator, as the tree could be bare-rooted and set back in place with relatively little stress from the process.)

Demonstrating arborist at this station:

Dave Leonard, Dave Leonard Consulting Arborist, Inc., Lexington, KY

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Tree Specialists manned the decompaction station at the MAA workshop on September 10, 2009.  Standing between two mature sugar maple trees, Rolf Briggs used a compaction meter (from Forestry Suppliers, Inc.) to show how thoroughly compacted the soil around these trees was (very).

Again, the arborists set up barriers to limit the area affected by blown-out soil and pebbles.  Rolf Briggs (right foreground) showed how to use a compaction meter, and explained that the green flags delineate the area to be decompacted.  Flagging the area for review by the client makes the limit of work clear to all parties.

Again, the arborists set up barriers to limit the area affected by blown-out soil and pebbles. Rolf Briggs (right foreground) showed how to use a compaction meter, and explained that the green flags delineate the area to be decompacted. Flagging the area for review by the client makes the limit of work clear to all parties.

Compaction limits the movement of moisture and of gases (oxygen included) in soils, and so can create significant problems for trees.  Trees rely on water being available to their roots, and on the ready intake of oxygen (from the air and from water molecules) for carbon dioxide discharged by those roots.  Compacted soils tend not to allow oxygen in in sufficient quantities, nor allow the steady release of carbon dioxide that a tree needs.  Breaking up the compaction, adding organic amendments to improve soil structure, and replacing lawn areas around trees with mulch beds are steps that benefit soil health, and as a result, tree health.

Decompacting soil around two sugar maple trees.  One man operates the air tool, blowing vertical trenches and mixing their backfill with a proprietary organic soil amendment that mimics forest duff.  The other operator mans the air hose, and tugs on it to signal to the operator.  Air tools are loud!.  Green flags indicate limits of the decompaction zone.

Decompacting soil around two sugar maple trees. One man operates the air tool, blowing vertical trenches and mixing their backfill with a proprietary organic soil amendment that mimics forest duff. The other operator mans the air hose, and tugs on it to signal to the operator. Air tools are loud!. Green flags indicate limits of the decompaction zone.

Tree Specialists prewaters the work area 24-48 hours before starting on a decompaction project, to hydrate the roots and help keep dust down.  As they proceed with the process, they begin to ‘fold in’ amendments.

For further information on decompaction, Briggs recommended an article in the current issue (September 2009) of Tree Care Industry Magazine on soil decompaction and amendment.

Demonstrating arborists at this station:

Tree Specialists, Inc.,  Holliston, MA

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The Massachusetts Arborists Association workshop on September 10, 2009, took place on a sunny, cool day at the Mass. Hort. Society’s headquarters at Elm Bank in Wellesley, MA.

Quite a few arborists and other landscape professionals attended the workshop, which began with slide talks and then moved outside to field demonstrations.

Quite a few arborists and other landscape professionals attended the workshop, which began with slide talks and then moved outside to field demonstrations.

This workshop focused on root issues, with demonstrations of what some of those issues are — conflicts with utility lines, the effects of poor growing and planting practices, decline due to compacted and poor soils, and inappropriate tree locations — and how they may be remedied.

Rolf Briggs and Tree Specialists set up shop at a couple of different stations to show how they use air tools both to decompact soils and to excavate utility trenches near trees.  The demonstrating arborists first discussed protective equipment, and showed what  they use when they employ air tools:  We watched as they put on respirators, helmets with face masks, ear protection, gloves, and either foul weather gear or jumpsuits — all necessary to protect from the great quantities of dust, soil, and stones blowing into the air.

To protect the surrounding area from flying detritus, Mike Hickman of Tree Specialists set up plywood or screen barriers around his work zone.  I’ve seen plain plywood sheets used; the Tree Specialist guys have figured out that hinging several sheets together makes for a sturdier barrier, a good thing if you’re using air tools with any regularity in anything but a wide-open landscape.

Hinged plywood panels keep the dust contained to the area around a trench.

Hinged plywood panels keep the dust contained to the area around a trench.

When it's necessary to dig a trench near a tree, air tools can do the job while preserving the tree's roots.  You can see roots crossing this trench, but plenty of space beneath them for a new conduit or line.  This trench was blown out with an air spade, and rocks and excess loose material after the blowing-out removed by hand.

When it's necessary to dig a trench near a tree, air tools can do the job while preserving the tree's roots. You can see roots crossing this trench, but plenty of space beneath them for a new conduit or line. This trench was blown out with an air spade, and rocks and excess loose material after the blowing-out removed by hand.

The power of compressed air will break up soil move it out of the way; it can also damage roots to some extent, by blowing root bark or feeder roots entirely away.  When using an air tool, experienced operators keep the nozzle moving to limit this kind of damage, and whenever possible (definitely not always possible in trenching work), they direct the air flow parallel to the direction of major root growth, away from the base of the tree.

Note the plywood barrier inside the trench as well, to focus the air blast and prevent soil from blowing into a previously blown-out section.

Note the plywood barrier inside the trench as well, to focus the air blast and prevent soil from blowing into a previously blown-out section.

Blowing out the trench.  This air tool is a new product that uses an auxiliary stream of water to help keep the roots hydrated and the dust down.  Tree Specialists is assessing this new feature.

Blowing out the trench. This air tool is a new product that uses an auxiliary stream of water to help keep the roots hydrated and the dust down. Tree Specialists is assessing this new feature.

After blowing out a utility trench, Tree Specialists simply returns the native soil to the excavated area.  They may add some amendments such as lime or humates, if they have already had soil tests done that indicate the need for such amendments.  And to mulch the area once excavation and backfilling are complete, they have developed a proprietary mix of chipped and composted wood fibers (mainly from tree parts 3″ and less in diameter), twigs, and leaves.  They use this same mix in their soil decompaction process, and note benefits to the trees from its use.

Mike Hickman pointed out that air tools break down soil aggregates and so obliterate soil structure in the area blown out.  This breakdown can be considered a disadvantage of using compressed air for excavation; in Mike’s words, “Destruction of some of the soil aggregates I see as a “con,” but proper horticultural practices such as mulching and site specific amendments effectively mitigate these cons.”

Demonstrating arborist at this station:

Mike Hickman, Tree Specialists, Inc., Holliston, MA

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Yesterday the Massachusetts Arborists Association held a day-long workshop at Elm Bank, headquarters for the Massachusetts Horticulture Society in Wellesley, MA.  Three arborists — Dave Leonard from Kentucky, Rolf Briggs of Holliston, MA, and Matt Foti of Lexington, MA — spoke about particular  root issues; Mike Furgal, from Northborough, MA, discussed the use of air tools in bare-root tree transplanting.  After hearing the talks, the hundred or so attendees split into groups and visited five stations on the Elm Bank grounds where the featured speakers were giving demonstrations on their topics.

It was a fine workshop, and I’ll be posting quite a few photos from it in the next few days.  Today, though, I’m only posting this photo:

Sugar maple whose root flare was excavated several years ago at a Bartlett Tree workshop given to demonstrate the new and revolutionary use of air tools in tree work.

Sugar maple whose trunk flare was excavated several years ago at a Bartlett Tree workshop given to demonstrate the new and revolutionary use of air tools in tree work.

Several years ago, I went with a friend to this Bartlett Tree workshop at Elm Bank, and we were among a smallish group who watched as an arborist blew several inches of soil away from the trunk flare of this Sugar Maple.  As I recall, the tree had been planted a bit deep, it was set in a fairly compacted lawn, and it was not looking as well as it might; at the time (this was perhaps seven or eight, or perhaps even ten years ago) it had about a six-inch caliper trunk and was not thriving.

Now, however, the tree looks really good.  It may have a little too much mulch around its base — built up since its excavation — but its foliage is deep green, its bark is intact (trunk injuries sometimes show up as a result of some kind of root trauma or injury), and it certainly has grown.  A mulch bed surrounds it and keeps lawnmowers away as it minimizes compaction.  If this kind of growth results from attending to root issues early on and from maintaining a tree properly, the arborists from this workshop may prove, down the road, to be responsible for promoting what truly may be the best arboricultural practices around.

Workshop speakers:

Dave Leonard, Dave Leonard Consulting Arborist, Inc., Lexington, KY

Rolf Briggs, Tree Specialists, Inc., Holliston, MA

Mike Furgal, Furgal’s Tree and Landscape, Northborough, MA

Matt Foti, Matthew R. Foti Landscape and Tree Service, Inc., Lexington, MA

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