Chunky mulch is best

azrael

More on N drawdown...
Most of the stuff I've read about is in reference to planting mixes.. and whether the OM additives are sufficiently aerobically composed (above-ground) before they are used in the mixes... viz my previous comments...and query making the same assumptions about the effect of toppings, such as mulch.

azrael

Here we go...
Hendrick N.D & Black K.A "Growing Media.."1994 (p36) make a simple statement about micro-organisms and decomposition of OM and the resulting depletion of soluble nitrogen and Nitrogen Deficiency syndrome...quote ."Only the material in contact with the soil will be decompsing. Draw-down of nitrogen will be minimal. Biological activity will gradually and painlessly mix the decayed organic matter into the soil.
Little soil nitrogen will be removed by chunky pine bark mulches. But if the bark contains a high proportion of fines, which settle to the soil surface, there can be some draw-down (and temporary toxicity problems)."

Eric Frei

Beautiful, that's what I wanted to read, which means chunky is best.

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a_lopa

Great stuff chunky mulch,I actually had a request for cypress mulch today when in times gone by people hated it.

IMO its one of if not the best mulch locally


4 sold loads today

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Drouin Tree Services and Excavator Hire | Excavator Hire - Drouin and SE Gippsland

willem

Hello Mulchers

I would like to know more about mulching and the mulch you use. In Holland we are not used to mulch around trees is gras areas. Could someone explain how a typical mulching job works.
Many thanks Willem

aphid

the most harm that i have noticed from wood chip mulch is improper application. the kind of people who live by their favorite four letter word (free) often pay the price later when they decide to spread a load of much when the moisture content of the ground is way too low. when the moisture does arrive the mulch gets to used by the mulch or acts a barrier leaving a very thirsty tree. Also muching in an area where the moisture of the soil is high and pretty much stays high could help sufficate the tree or create a environment for the wrong kind of organisms. I always thought that the nitrogen robbing bacteria is at its greatest risk to the tree is while contents of leaves and sappling materials available for the bacteria to multiply at very demanding rates. cellulose decomposes at a much slower rate.
I'm new and you don't have to be nice

Sean Freeman

Here are a few of the aspects of applying mulch that I have learnt over the years, and from others.

For established perennial plants such as trees the impact of nitrogen draw down is not very significant at all, certainly if you have an ancient tree or one in very poor state of health any additional stress should be avoided...the application of green non composted mulch of any kind is to be avoided.

Select your mulch for trees based on the leaf litter composition that the species would normally have in the relatively unmanipulated forest environment....ie the mulch should be made up of leaf and wood chip from the same species and from other species of the vegetative community in which this tree species grows. (Shigo once said that someone would become very rich by carefully and fastidiously seperating woodchip by species and composting those chips seperately then applying the woodchip to the same tree species (chip free from pests and pathogens of course!)

Your mulch should not be deeper than 150mm-200mm and should never be allowed to build up against the stems of the trees.

The purpose of the mulch is primarily to be the carbon source for the soil food web...to be broken down by the lowest trophic levels in that web, all the commonly understood benefits of moisture/temperature/weed control are good but they are very much secondary.....if your mulch does not break down and "disappear" within a month then your soil has real problems with regards its biological content.

The issue of getting carbon into the soil horizons when formal turf is the desired aesthetic is always a hard fix...vertical mulching does in my experience work though it is slow and back breaking work. I have seen radial trenching done, and of course soil drenching with various compoct teas etc...but remember these teas as useful as they can be are not providing carbon, the fuel source in the soil. I really think the most effective management approach is to argue until you get approval to have small mulch circles (disks) then each year ever so slightly steal more and more turf until you have what approaches drip line coverage.

willem

Hello Sean
Thanks for the info!!. You say the mulch has to dissapear in a month. What happens afterwards you come back and fill the area again with a fresh load of mulch??

Willem

Sean Freeman

Hi Willem, the mulch doesn't have to disappear but it should be consumed by the fauna in a healthy soil...in the forest environment the organic layer is perpetually being added to, we can't really recreate that but we can replenish mulch every 6 months (in a well organised and budgeted situation). Nothing is static in nature so as you add more mulch to the soil very gradually you are providing the best possible environment for healthy root growth. Its really never ending since it is unlikely that the trees we work on in the urban environment will ever be permitted to develop the kind of density of canopy coverage typical in forest systems..and the recycling of carbon that goes on there.

aphid

the carbon cycle is where microorganisms carry out there most important function in the maintenance of life on earth. all organic compounds contain carbon. during degration of organic materials microorganisms are performing a process called mineralisation, basicly elements that were bound to the carbon are released and available for individual plant cells utilize them. mulching with chunky mulch very much fits the best title if it is able to (if not allready) become a humus state. chunky mulch that has both the larger materials that are slower to decompose (cellouse,chitin,ligin) and the quickly decomposed materials. this is all explained very basicly. a stabilising effect of mulching like this over time would benifit the soil because you would be supporting a complex microflora . an active soil will develope a soil with a better crumb structure.

Eric Frei

Sean, you wrote 150mm to 200mm deep, that's like 8", you sure? We're talking gardens here not development sites with machinery.

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Sean Freeman

You're right Eric getting greedy and excessive there sorry. That is the depth for compaction bridging! My bad.......

Bernard Keays

Sean,

Do you have a copy of that article by shigo?

'Shigo used to say that someone would get very rich one day by sepersting their mulch into piles by species of tree chipped....'

I remember reading this somewhere but couldn't recall where.

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Bernie

Galbee

Great info guys
i have been selling my chips for years customers approach me on jobs for truck loads of it on road side jobs, lots of people with veg patches ,i never understood that but i dont grow veg personally, they store it in a corner it must be the micro organisms they are after,

Sean Freeman

Bernard, its in the video collection of the talks he gave when over here in the early nineties. Not sure if you can still get them but expect that you can.

fatkoala

I never knew adding carbon to the soil was so important it was not once mentioned during my certificate four course at Burnley (Melbourne).

Your saying Sean that the breakdown of carbon in the soil does what exactly ? What is the carbon broken down into ?

I believe what your saying as wheat farmers here a injecting the exhaust fumes from their tractors back into the soil as they sow their wheat to great effect with higher yields and lower fertilizer imput.

How are plants able to grow hydroponically then if all they are fed is nutrients and trace elements ?

Sean Freeman

It is sad that it seems to take our educational institutions such a long time to incorporate the advances in understanding that have been made in the last 10years. However it is possibly that I used the term Carbon where your lecturers might have used the term 'organic matter'.

I'm not going to write pages and pages explaining soil biology but I will provide more detail than my simplistic statement about Carbon.

Carbon in the form of simple sugars forms the energy source for the first trophic level within the soil food web.

It is within the portion of the soil described as the organic matter it can be present or become available in the soil many ways here are some described on the USAD NRCS website.....


Even some of this is out of date now...the building blocks of humus have been over looked for a great many years and the actual compounds responsible for the binding of small soil aggregates has since been established to be a protien molecule named Glomalin...the superglue of the soil and yes another critical arrangement of Carbon...possibly the most important of all given the generally accepted view on increasing atmospheric Carbon dioxide.

So....what is it that the breakdown of Carbon provides??

The energy that drives the entire soil food web basically.

BUT Carbon has a great many other roles to play beside as an energy source (in the form of sugars), it provides the building blocks for humus and humic acids which not only hold our sols together but have the ability to lock up enormous amounts of Carbon dioxide (Glomalin), it provides the niche habitat for a great many of the first trophic level organisms (in the form of detritus especially in its smallest scale form...dysfunctional hyphal tubes of fungi).

If you really want to understand how trees grow and how to manage them, you need to understand soil biology...the benefit for you is that along the way you might gain a greater depth of understanding about a whole range of other important aspects of the natural world and our impacts on it.

windthrown

As for carbon, all plant matter basically breaks down into carbon dioxide and water. Just like when you burn gasoline. The difference being that in plants, there are longer chains of hydrocarbons in plant fiber and wood than in gas. What breaks them down are microbes in the soil. Those microbes need nutrients to do that. They also need surface area for a supply of air and water to work with. So in effect, large chunks of mulch means less surface area, and hence they break down slower and rob less nutrients from the soil in the process.

Large chunks also do not create an abcission layers on or in the soil. If you take a potted plant that is growing in a lot of peat and dig a hole and stick it in the ground that is mostly heavy clay soil, an abcission layer will be created. Water cannot pass through the abcission soil layers, and roots cannot grow through them either. I have seen many times where old landscape plants were strangled in their own root balls and they were growing in the same area as the pots that they were originally planted out of. Fine mulch can create ancission layers on soil and cause water to run off under the mulch.

I use all the mulch that comes out of the chipper that customers do not want. Somtimes it is fine, mostly fir needles, and I pile that up and compost it and use it in potted plant soil mix (I mix all my own potting soils) or till it into the soil. It gets really hot really fast, and cooks in about a month. I also use the chunky wood stuff as garden mulch topping, the chunkier the better. The bamboos love really coarse chipper chunks. I have 6 inches of "coarse super-chunky" mulch in my bamboo gardens. I also use it for pathways around my gardens to keep the mud down. I also use 'noodles' from my chainsaw cutting rounds lengthwise as a soil topping for my strawerry and garlic beds. Makes a good seedless 'sterile' mulch that water goes through just fine. Its about like using straw or hay, but no seeds. It robs some soil nutrients, but all at the very top of the soil where the roots of the plants are not very active.

My neighbor is a nut for making complex soils for his garden beds, and he completely overtills his garden. He also chips and then rechips his chipper mulch in a Bearcat chipper until its a very fine dust. It breaks down very fast, within a year. It robs all the soil nutrients in the process. So he adds a lot of chicken manure to replenish it. He is also polishing his soil beds about 5 inches under the top from all the tilling he does. There is nothing I can say to stop him doing it. I till at most once a year, and I feed the worms tilled in composted chipper mulch to do the real deep tilling and soil tunneling.

aphid

understanding that mineralisation has a far greater role to the plant than the amount of carbon in the soil because of the fact that a plant takes in carbon dioxide from the atmosphere at the stoma in the leaves. the uptake of the needed elements through the root system occurs after it is unbound from the carbon. the interactions of the things that sean has listed help this to happen. a healthy soil benifited by mulching also exchanges air with the atmosphere better

very_sarcastic

Cool dude, couldn't agree more. A lot of clients dislike the look of chunky bark for mulch and opt for the 'neat' fine grade mulches for their gardens. A lot of these form an impenetrable 'crust' over the soil surface. Sweet chunky bark is ABSOLUTELY THE GREATEST for surface water penetration, and also IMO way more attractive. I cannot believe how dry some of these soils are from being smothered by the finer grade mulches (which are usually reapplied 4" deep every five minutes to keep that new clean fresh look)