Deep Tree Root Feeding

JuneBug747

A friend of mine was telling me about a landscaper she hired that offered deep tree root fertlizing. They use a machine that pushes air into the ground and then pushes organic fertlizer into the ground. Just wondering what the "experts" thought?

Roller

Tree fertilizing in the wrong hands spells disaster for trees, in the right hands deep root feeding [actually not so deep root feeding] can be very beneficial for declining urban trees.

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JuneBug747

Thanks for the reply. Are there different methods? The logic behind this made sence, get to the root of the tree and feed it so that the roots don't have to come closer to the surface.

Eric Frei

Junebug

I'll move this thread to the Ask an Arborist area.

Deep root feeding is like so many other things people do to trees ... is it necessary? Like many people prune and cut trees, seldom for the trees good but for their fetishes.

Over fertilizing trees or with the wrong fertilizer as mentioned above can also spell trouble. One of the illusions we fall to is that when a tree is lush and green and booming on with growth ... it's healthy right? Not so.

Trees generally will put off defending themselves from pests and diseases over growing ... that's their code, grow more to get more light and the biggest tree of the forest succeeds where the smaller ones get shaded out.

Too much nutritional value could see trees with over extended structure, heavy foliage and possible more bugs.

Whilst the decompaction and aeration of the soil in compacted areas is beneficial so is good soil care, which means building and providing a good microbial soil with worms, beneficial fungi etc (mulch is the best).

So, what is going in the ground is important. In most cases some Seasol/fish style product benefits as does some organic matter perhaps liquid blood/bone. Keeping down the nitrogen (n) will also prevent rapid growth and lush foliage.

So, knowing what the tree needs (if anything) and knowing what the soil is deficient in are the beginnings of the project. But what you will usually see is a "one size fits all" approach to this.

For instance, the trees leaves are showing some yellowing so landscaper deep root feeds and has a higher N product. The tree improves slightly however you notice a sap sucker infestation developing. Under closer analysis what we discover is the soil was out of the Ph range needed for the tree to take up nutrient that was already present so we added and watered in lime and the tree is fine.

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Roller

I'm sorry it has nothing to do with keeping the tree roots lower in the soil, or feeding the tree, trees cannot be fed,trees feed themselves through photosynthesis, IE sunlight converted into sugars and starches.

The wrongly named deep root feeding, is in-fact all about applying beneficial macro and micro fertilizers, fungal spores, cleated iron etc. This type of work is very specialized, but like most things hacks have jumped onto the bandwagon.

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JuneBug747

wow. thanks.

mdvaden

Whether through roots, or applied to the surface, one warning sign I know of is if a company offers the fertilizing as a ROUTINE service, without much thought about soiil tests or diagnosis.

Some companies out our way, just apply it on schedule like mowing a lawn, just not weekly.

We get a lot of wind, rain and occassional ice here, and a lot of fertilized trees - even for better causes - receive heavy damage due to extra growth.

The branches are longer, thus more leverage in the favor of ice, snow and rain weight. And the leaves are bigger, or needles, providing more surface area for precipitation to build-up weight.

So in one way, some of the slightly nutrient deficient trees, hold up better than the properly fed ones.

Its a fine service when a trained specialist uses it sparingly.

JuneBug747

Huh, never thought of it that way. Thanks for your input.

redstree

This is based on a machine developed in Germany, I do believe. I have watched one of these machines in operation. It is a self contained machine that has an air compressor and dry fertilizer/vermiculite injection chamber. They push a hollow needle down into the soil and first inject high pressure air followed with the dry ingredient. The air fractures the soil structure, sometimes as far as 10'(3m) from the injection site, and the dry ingredients hold the fractures open, allowing water and air to penetrate the ground.

Where compacted soil is an issue this can be a great machine. Research done in the 1960s in the USA for a product called the SubJet showed that this sort of sub-soil injection was very effective. In one study that I saw it compared the injection of air, water, and liquid fertilizer on test trees.

Comparing the control trees, where nothing was done, to those injected showed the largest change came between doing nothing and the injection of air. The injection of water or liquid fertilizer showed incremental improvement, but nothing compared to just fracturing the soil with air.

I am not sure if the Subjet research is available online due to the date, but I have seen the hard copy of this report and will personally vouch for it.

Over the past 27 years I have either performed this type of operation myself or supervised it hundreds of times. It really works.

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