HMM YES, on further consideration I was the one confused...
mulch wouldn't pull nutrients for the soil more than 1mm or so (less
than 1/8 inch).. UNLESS incorporated.. and by the time it is shredded
enough for frost or earthworms to do this... it would already be well
on its way to decay...
--- In email@example.com
, La Clarine Farm
> Linda, I am sure the increase in water retention provides a better
> microclimate for the soil microbes and that's why they are seeing
> increases in growth on the mulched plots. Happy microbes = happy
> plants, right? I agree with you that the mulch layer impacts the
> nutrient levels very little directly.
> My experience is that this layer eventually gets pulled into the
> earthworm and frost actions, where it slowly gets broken down and
> releases various nutrients. But its greatest use is for soil moisture
> Linda Shewan wrote:
> > I could argue with this but I am not as scientifically based as
Jeff so I
> > would certainly say things wrong BUT my understanding is that the
> > chips
> > lock up nitrogen ONLY if they are dug into the soil. Left on top they
> > do not
> > 'pull' nitrogen out of the soil. I believe there are studies
> > supporting and
> > dissenting this view but a couple of supporting sites are below:
> > A 2004-2006 Washington study showed that applying a 5-foot wide,
> > thick layer of wood chips provided the best weed control in all three
> > years,
> > although it needed reapplication in year three. This treatment also
> > produced
> > the greatest tree growth and fruit size.
> > In a related trial, a Gala apple block was used to compare a
> > chip mulch in the tree row with a herbicide strip. In the first year,
> > mulched plots consistently had 15 percent to 20 percent higher soil
> > moisture
> > at the end of each irrigation cycle than the bare ground plots. In the
> > second year, the two treatments were watered independently
> > need, and mulching reduced cumulative irrigation application by 20
> > to 30 percent.
> > -----
> > Concern: Wood chip mulches will tie up nitrogen and cause
> > plants.
> > Evidence: Actually, many studies have demonstrated that woody mulch
> > materials increase nutrient levels in soils and/or associated plant
> > foliage.
> > My hypothesis is that a zone of nitrogen deficiency exists at the
> > mulch/soil
> > interface, inhibiting weed seed germination while having no
> > established plant roots below the soil surface. For this reason, it is
> > inadvisable to use high C:N mulches in annual beds or vegetable
> > where the plants of interest do not have deep, extensive root systems.
> > From: http://www.sustainable-gardening.com/WoodChips.php
> > <http://www.sustainable-gardening.com/WoodChips.php> and an
> > discussion on
> > http://www.gardenrant.com/my_weblog/2008/09/the-hort-guru-a.html
> > <http://www.gardenrant.com/my_weblog/2008/09/the-hort-guru-a.html>
> > Cheers, Linda
> > From: firstname.lastname@example.org
> > <mailto:fukuoka_farming%40yahoogroups.com>
> > [mailto:email@example.com
> > <mailto:fukuoka_farming%40yahoogroups.com>] On Behalf Of Jeff
> > Sent: Sunday, 1 March 2009 1:17 PM
> > To: firstname.lastname@example.org
> > <mailto:fukuoka_farming%40yahoogroups.com>
> > Subject: [fukuoka_farming] Re: Wood chips as mulch: Re forest soils
> > and more
> > soil science
> > This email is an attempt to clear up the misunderstanding that have
> > arrisen as of late about wood mulch
> > -and of course how this relates to forest soils and
> > how separately it relates to natural farming
> > I will start with the sciency part,., then get more common speak as
> > the post goes on
> > > It would seem to me that the fact that many forests have super
> > fertile top soils that are many feet deep could possibly be that
> > multitudes of > leaves, sticks, branches, trunks, etc., have fallen
> > undisturbed over > millenia.
> > when you say fertile soil you must have a basis of comparison..
> > ok so old prairie soils have deep dark A horizons.. the rotting roots
> > of the grasses are responsible for this .. this is the theory behind
> > 'rhizodeposition' that Bob Monie toughts..
> > this works because of several factors..
> > a) grass roots go deep instead of spread out like forests
> > b) grass roots are upto 75% of the primary production as opposed to
> > around 18% for trees (mostly goes into 'wood')
> > c) roots actually are somewhat resistant to decomposition due to
> > content of anti-microbles and higher percentages of lignin
> > so the result is somewhat decayed organic matter with high nutrient
> > value mixed deeply in the soils lll this is for prairie soils
> > in forest soils the majority of the organic matter is above the
> > the leaf and stick litter is called the o-horizon...
> > in frigid climates like boreal forests this can over eons become
> > several feet thick, also in bog/peat situations this can likewise
> > become thick- this is due to slow decomposition because of cold or
> > in temperate climates it is at most inches thick...
> > in tropical climates it is even less (usually less than 1")
> > immediately below the O-horizon is an E horizon... this is where all
> > the acids from the leaf litter remove the nutrients and send them
> > packing.. ending up in the stream or deeper in the soil profile...
> > the nutrients then are bound mostly in the living matter and the
> > O-horizons..... (recently dead stuff)
> > but the soils are often 'deep' because the acids do break down bedrock
> > and roots crack it to increase weathering of the soil...
> > so the actual soil profile might be deep but the nutrients are still
> > mostly shallow...
> > I fail to see how adding wood chips to soils could possibly
> > > decrease the fertility of soils, unless one has been adding chemical
> > > fertilizers for quite some time, resulting in dead soils. Perhaps
> > I'm mistaken?
> > >
> > It doesn't decrease the fertility... it temporarily sequesters
> > them.... this has to do with the natural balance of the carbon to
> > nitrogen ratio.... this topic has been covered several times in the
> > archievs....
> > basically bacteria have a low carbon to nitrogen ration relative to
> > the wood chips this means the bacteria suck up all the nitrogen so
> > they can break down the wood chips... the bacteria being tiny and
> > numerous are much better at getting the nitrogen then the plants are.
> > so for 1-3 years you have low 'available' nitrogen until the bateria
> > catch up with the wood chips...
> > the nitrogen fertility of forest soils is usually built up during the
> > early successional phase of the forest.. that is in the meadow and
> > shrub stage.. there are many meadow and shrubs that fix nitrogen and
> > very few trees that do so.. typically the nitrogen is maxed as a young
> > forest and slowly declines as some is washed out...
> > it is the bacteria and fungi's ability to hold onto the nitrogen so
> > well that enables the forest to be so productive without fertilize..
> > when you cut down a forest you do away with their food supply and the
> > bateria and fungi die, and the nutrients get leached.
> > > > Dear Jeremy,
> > > >
> > > > I think woody material contains high amount of cellulose. It
> > > decomposes very> > slowly and after decomposition that releases
> > toxic acids that can be problematic to the plants.. I dont know the
> > specific names of these acids.
> > this is only true of certain trees .. not all trees have these
> > compounds..... trees that are noted for their resinous oils (Eucalpyt,
> > leaurals) and conifers (pines, spruces etc) are likely to result in
> > these acids..
> > there are many many specific ones, and plant biologist and soil
> > scientist have different terms for them.. the
> > term I'm familiar with is phenolitic...
> > pheno- refering to the benzene right structure of these acids...
> > and litic refering to lysis.. or the breakdown of the orginal organic
> > matter
> > There may be other compounds that contribute to this but they are less
> > known.. and don't occur in large families like the previously
> > mentioned plants
> > this is one of the reasons conifers are not highly recommended as
> > mulch for gardening.....and braodleaved trees are prefered...
> > I would think a moderate amount of conifers once or twice would have a
> > minimal effect...
> > generally when these things are measure and disscuessed it is in the
> > terms of geologic time development of soils...
> > I would think that after once or twice adding the conifers, and
> > regular mulching of other organic matter, you would no longer need the
> > conifer mulch to effectively garden and restore fertility
> > > > > If I recall correctly, woody material has such a high carbon
> > > content that it ties up nitrogen unless broken down by fungi. As
> > already mentioned, you can bury the material to help it decompose. You
> > could also spread the chips out and innoculate with fungi spores. You
> > may want to try Stropharia rugoso-annulata or Pleurotus species.
> > > > >
> > >
> > this is exactly correct...
> > interestingly enough research pointed to by Stamets in Mycellium
> > Running indicated increased yeild for certain vegetables when grown in
> > combination with the above mentioned fungi...
> > and even more interesting was that fact that the best yeild increases
> > were for the brasicas ... which don't form VAM or AM mycorhizal
> > assocaions like most other plants.
> > ugh..
> > just say so you have any questions or need anything clarified..
> > I'm fighting a cold and might have skipped over something important
> > jeff
> > [Non-text portions of this message have been removed]