Green mulch.

[beastmaster]

I recently did some work with a Company that really impressed me with their knowledge and professionalism and attention to detail. They teach the customer about their trees and how to care for them. One thing they highly recommend is mulching. I couldn't agree more with that, but at the end of the day we used the chips from that job and laid it down for mulch. Its my understanding that green new mulch can rob available nitrogen from the soil as its decomposed. I know this to be true if its added to a compost and used as a soil additive. But I am unclear if it could be a problem when used as a surface covering to control weeds and what not around trees and ornamentals. If so, could a slow released fertilizer spread out over the mulch be beneficial?
I think this is a real problem when planting a new tree or grass over where a stump has been ground and the grindings left or mixed with the soil.

 

[cedar]

It is perfectly fine to apply fresh wood chips around trees and shrubs. Read this article and it will answer the question you have about nitrogen and explain the benefits of fresh wood chips - http://aswcd.org/Woodchips.pdf

 

[Raintree]

It is perfectly fine to apply fresh wood chips around trees and shrubs. Read this article and it will answer the question you have about nitrogen and explain the benefits of fresh wood chips - http://aswcd.org/Woodchips.pdf

Sure would be nice to put that fresh wood chip myth to bed once & for all.

 

[ddhlakebound]

It is perfectly fine to apply fresh wood chips around trees and shrubs. Read this article and it will answer the question you have about nitrogen and explain the benefits of fresh wood chips - http://aswcd.org/Woodchips.pdf

Nice article, and I agree with most of it, but it does not explain the processes of nitrogen availability as chips go from fresh to aged. From the article -

My hypothesis is that a zone of nitrogen deficiency exists at the mulch/soil interface, inhibiting weed seed germination while having no influence upon established plant roots below the soil surface.

ScienceDirect.com - Forest Ecology and Management - Nitrogen immobilization by wood-chip application: Protecting water quality in a northern hardwood forest

This article suggests (through measurement) that fresh wood chips applied as mulch greatly decreases the nitrogen available to plants for a time.

I really don't care either way........I just want to know what's correct, and there are lots of people saying lots of very different things.....much of which is hypothesis, guesswork, and anecdotal evidence.

 

[beastmaster]

Thanks for the link. It address my question pretty well. At lest as far as surface mulching goes. But stump grindings left in the hole may be different, because of the C:N ratio is lop sided since there is no green material as a nitrogen source.
I am trying to sift throu a lot of things in arbor care that are more myth based then backed by science. We hear something enough passed on from person to person it becomes true and excepted. I like knowing the real deal. I may not be the sharpest tool in the shed, but there are some smart people on this site, that is why I sometimes ask stupid questions. Thanks for the answers.

 

[Zale]

Over the years, I have probably used 100-150 cu. yds. of fresh chips in my own landscape. Never lost a plant. IMO the most important thing to consider when using fresh chips is that they are free!!!

 

[sgreanbeans]

Looked in the books, nothing. I am sure that there is some toxicity issues, but I couldn't find it. We have a pretty big nursery here that takes chips to heal in their B&B trees. They have really nice stuff and all the trees look like they are growing just fine. I do know that if you do use it, it will decompose quicker and form a "cake" the thick chunks that look like cow pies, when it does this, it blocks water and oxy, so ya gotta break it up. I don't ever do it (give them chips), people think that chipper mulch is going to be like actual ground and dyed hardwood mulch, they get PO'ed when they realize that they just dumped a bunch of leaves and twigs with the chips.

 

[since16]

green

I dont know anything about the fresh chips being bad but I know it doesnt hold moisture like real mulch and that is half the reason for laying it down.

 

[echo271]

I live in central florida and the reason we don't use green mulch is the bugs and ants that are attracted to fresh chips here

 

[arborjockey]

I've been told the chips pull nitrogen from the soil (was told that the process of actually breaking the cips down is what strips the soil) although as just a mulch may not harm anything. The other consideration is what kind of chips? Pine,black walnut, eucalyptus? We dump all green waste for free here. They also give free mulch away as well. The mulch is absolute poison. When I see it under trees my 1st suggestion is to remove it and put down organic soil then any topping from chips (of a known species ) to gravel. Never know what that big tub ground up and you take home. If there's lots of wood (chips or sawdust) I sweeten it up withmanure

 

[pdqdl]

Ok guys, here is the easy answer on mulch and nitrogen:

Wood chips are mostly cellulose, and not a whole lot of nitrogen from plant proteins. They do not do anything at all to the nitrogen in the soil, whether green or completely composted.

Fungi, however, love to munch on the wood chips as an energy source, which they use to fuel their growth and reproduction. Since wood doesn't have much nitrogen in it, the fungi sink their little mycelium down into the soil for something else. As they grow on the wood chips, the fungi DO absorb some of the nitrogen from the soil and bind it up where the roots from your landscape plants can't get to it. So...wood chips lead to some nitrogen reduction as they decompose.

Eventually, the wood is mostly turned into CO2, water, and whatever other minerals were present in the wood to begin with. By the time it is mostly turned into compost, the fungal growth is also being turned back into nitrogen, and the net change of nitrogen in the soil is a slight increase, due to the small percentage of plant proteins that have been added to the area.

The best example that can be seen of this phenomenon is the green rings that form around "fairy rings", a common lawn ailment.

Notice the darker green grass on the outside from increased nitrogen, while the lawn in the center areas tends to die off from competition with the fungus.

If you are worried about your landscape plants starving from the scenario described above, just throw some fertilizer on the pile, and don't worry about it anymore.

BTW: drilling holes into stumps and adding high nitrogen fertilizer is the best way to get them to decompose quicker. Short of putting a stump grinder on them, of course.

 

[pdqdl]

Here is a similar description on the problem from "The Dean of Green": http://www.wglt.org/podcasts/dean_of_green/audio/dog120608.mp3

It is mostly about concerns about gardening, but the idea is about the same.

 

[Jeffgp26]

Its the heat

As soon as the chipper spits those green chips in the bed they start decomposing. You can tell by moving the chips in the bed around. They are hot! If those green chips are put around plants, they will "burn" the plants. Best to wait a while depending on the climate of the area your in.

 

[pdqdl]

Decomposing wood chips only get hot when they are piled deep enough to insulate the pile. 2"-4" is the usual depth for wood chips, and that will only protect the plants root zone from the summer heat. At that depth, it will never get hot enough to injure any plants.

Deep piles of compost can get to 160°, but that doesn't happen at "mulching" depths.

 

[arborjockey]

Looked in the books, nothing..

If it ain't there what we gone do? Some body call the super heroes at ISA

No no no pdqdl throw them fancy paper with words on it away. Waist of time here anyways. All you neened was a thermometer ......its the heat man its the heat.

Just kinda funny when pdqdl put a scientific explanation, broken down into laymans terms, 2 post up. Then we get Labron saying "its da heat fool its da heat"