[Terrapreta] To compost or not; and some other points

[Frank Teuton]

Hi Kevin, Janice, Dr Karve, et al

The issue of 'to compost, or not to compost' is a complex one with answers 
that vary according to the specific needs of the situation---both as to the 
nature and character of the materials in question, and the nature and 
character of the soils and crops being treated.

High temperature composting offers rapid and sure destruction of pathogens 
and weed seeds and other undesirable biology in the start materials. It can 
also offer substantial savings in handling and transportation where the 
fields and start materials are far apart, with fewer 'transport miles' 
needed where materials are composted onsite prior to transport off site. 
However, the process itself also requires handling of materials and 
management resources...there are no free lunches to be had here. Sharp 
pencils should be applied to the analysis.

Gardeners, including organic gardeners, have been debating the relative 
merits of composting versus direct application of residues for centuries, if 
not millennia. In the last century Helen and Scott Nearing, Ruth Stout and 
others demonstrated the possibilities of mulch gardening. Eliot Coleman, 
bridging the last and this century, has used both methods with success in 
various ways. Fred Magdoff and Harold Van Es, in Building Soils for Better 
Crops (2000, Sustainable Agriculture Network), in the chapter Making and 
Using Composts, spend several pages pointing out various reasons why and how 
compost can be made, but conclude with:

   "Without denying these good reasons to compost, there are frequently very 
good reasons to just add organic materials directly to the soil, without 
composting. Compared to fresh residues, composts may not stimulate as much 
production of the sticky gums that help hold aggregates together. Also, some 
uncomposted materials have more nutrients that are readily available to feed 
plants than do composts. If your soil is very deficient in nutrients, plants 
may need readily available nutrients from residues. Routine use of compost 
as a nitrogen source may cause high soil phosphorus levels to develop, 
because of the relatively low N:P ratio. Finally, more labor and energy 
usually are needed to compost residues before applying, than to simply apply 
the residues to the soil directly."

Regarding the application of energy to the soil, and the definition of N as 
a 'mineral'---it's again complicated. Nitrogen is mostly stored in the 
earth's atmosphere in double bonded form which is difficult to break. 
Lightning does some of the work of breaking it, but much of it is done by 
microorganisms in exchange for energy. Plants of the legume group ( clover, 
alfalfa, peas, beans, vetches, certain trees like acacia and locusts, etc) 
harbor bacteria in association with their roots---they feed these bacteria 
exudate materials rich in energy, for which they receive nitrogen produced 
by these specialized bacteria. There are also free living bacteria which fix 
nitrogen, for example Azotabacter--but they need energy rich substrate to 
work with. Nitrogen is not a mineral in the sense that phosphorus and 
potassium usually are, but the term 'mineralization of nitrogen' is part of 
our legacy of confusing terminology:

   "When fed nitrogen-rich residues such as dung, the soil life burns some 
nitrogenous compounds for energy, releasing the nitrogen in inorganic form, 
primarily ammonium. This is called mineralization, and makes the nitrogen 
available to plant roots. "

For more details on the nitrogen cycle see: 
http://www.nofa.org/tnf/nitrogen.php


Re 'in place composting'---the reason it usually doesn't heat, or cause 
'burning' of plants, is that the layers of materials are thin and excess 
heat escapes, and because a balanced mix of materials will usually not do 
the bad things that, for example, a thick layer of fresh grass clippings 
could do, namely burn both thermally and chemically. By mulching with 
relatively C rich materials like leaves, or dried hay, or even by simply 
drying the grass clippings first, you can avoid most problems...many thin 
layers applied over time are also better behaved than a single thick layer.

Re the benefit to plants of a mulch layer: the energy provided in a steady 
but not excessive stream to the soil allows for superior soil structure to 
develop, which greatly facilitates plant roots in doing their good works. If 
you go and till in the residues you suddenly expose all the materials to 
moisture and soil and disturb the soil structure. If the crop you are 
growing requires tilled soil it is best to till in moderately carbon rich 
materials, eg leaves, in the fall and allow them to decompose well prior to 
a spring crop, to avoid nitrogen immobilization. This also allows the soil 
to recover somewhat from the indignities offered it by tillage. Nitrogen tie 
up from mulching is rarely an issue; it is the incorporation of the residues 
which monkey wrenches the whole system. This has to do with the actual 
surface area of organic materials exposed to soil organisms, I believe, as 
well as disruption from tillage. Mulching also reduces the need for watering 
and maintains even moisture and shade to the soil.

If you are growing a high value selection of organic vegetables for market, 
you will be required to allow 90-120 days from the use of any type of fresh 
manure to the soil to the harvesting of an edible crop. Compost will likely 
be your best friend in that case. One way to use the composting process to 
good advantage would be to add the biochar to the compost at some point in 
the process, which would allow you to spread both in one go, and to charge 
the biochar with biology. This would avoid all the negatives of sterile 
flying charcoal dust.

As I understand it the point of the New Green known as Black is to tap the 
biomass potential for fuels and return part of the materials to soils to 
achieve better soils and carbon negativity. The recommendations to char at 
relatively low temperatures and to not allow random offgassing of byproducts 
are in the vein of environmental concerns...the low temps allows more oils 
and other materials to stay with the char with biological benefits to soil 
life, but also to allow the preservation of better char structure, ie, more 
complex habitat for the soil foodweb. The edible materials that stay in low 
temp char are relatively rapidly consumed, as I understand it...but the 
structure of low temp char should be its structure for hundreds of years or 
more.

Adding high temp char to soil may be a nice thing to do for carbon 
sequestration reasons, but it doesn't have the 'win-win' character of adding 
better quality char to soils, as I understand the argument.

People have asked how to add charcoal to perennial stands of switchgrass. I 
have no experience with that crop, but considerable experience with turf and 
pasture. Core aeration of turf followed by topdressing allows substantial 
infiltration of topdressing materials, which could include biochars, into 
the cylindrical holes made by the core aerators. Mixing the char into a 
composting or vermicomposting process would allow it to become biologized, 
thus more likely to be bio-incorporated into the soil by soil mesofauna. 
Worm populations of 1-2 million per acre have been reported in some 
switchgrass stands, so it seems reasonable that if the biochar can be 
presented to them in an attractively edible state, they would be pleased to 
help incorporate it.

I hope this contribution is helpful in some way,

Frank Teuton

----- Original Message ----- 
From: "Kevin Chisholm" <kchisholm at ca.inter.net>
To: "Janice Thies" <jet25 at cornell.edu>
Cc: <terrapreta at bioenergylists.org>
Sent: Thursday, April 19, 2007 9:08 PM
Subject: Re: [Terrapreta] Soils, sugars and nutrient elements-response


> Dear Janice
>
> Janice Thies wrote:
>> Dear Kevin,
>>
>> I can address some of these questions for you and clarify a few
>> misconceptions.
>>
>> First, plants do not gain their energy from the soil.  They
>> photosynthesize, meaning they use energy from the sun to make reduced
>> carbon compounds (such as sugars) necessary for growth, development,
>> reproduction and metabolism from carbon dioxide.  This does not mean
>> that they do not respire, they do.  They use the organic C compounds
>> (sugars) they produce via photosynthesis to generate cellular energy for
>> other metabolic processes.  So, where you comment that the plants are
>> getting energy by feeding sugar to the soil - this is not the case at 
>> all.
>
> Sorry... this was sloppiness on my part... Dr. Karve's sugar method is
> clearly intended to "feed the soil", rather than feeding the plant.
>>
>> Instead, what is likely happening is that soil heterotrophic organisms
>> (decomposers) are using the sugars themselves for energy.  Where there
>> is abundant energy (carbon compounds, such as sugars) and abundant
>> mineral nutrients (such as N, P, K, Mg, S, etc), the mineral nutrient
>> elements will increase in concentration in the soil solution as they are
>> in excess of the cellular needs of the microbes.  Hence, more of these
>> nutrients are available for plant uptake (because they do take these up
>> from the soil solution). Where there is abundant energy and mineral
>> nutrient elements are scarce, then they will likely be "immobilized" in
>> microbial biomass and NOT available to plants.  This is the explanation
>> for the 'robbing N from plants' part of your question.
>
> OK.
>>
>> On in place composting, you need to be careful of a few things.  The pH
>> of the materials incoming, their C:N ratio, salt concentrations and how
>> much of a good thing there is come to mind immediately.
>
> With "natural" materials, such as agricultural waste, food waste, etc,
> is there any concern for pH? What are some examples of situations where
> pH would be a significant concern? When you refer to "salt", do you mean
> the equivalent to ocean spray, or perhaps some other salt source?
>
>  One hallmark of
>> composting is the thermogenic stage, where the pile heats up.  This can
>> help begin the decomposition of more recalcitrant materials, but can -
>> if happening in place - burn your plants literally.
>
> I can see heating as a concern, when teh compost bed is rich, well
> balanced with C/N, and well aerated. Is overheating a problem with
> composting in place, where aeration is likely to be inferior, and teh
> rate oc composting slower?
>
>  If urea is present
>> in high amounts, this can cause another kind of leaf 'burning' to take
>> place.  If the pH of the material is too high, N may be lost an ammonia
>> to the atmosphere, if the pH is too low, plant roots will be very
>> unhappy.
>
> If manures and greens are used as the source of Nitrogen, rather than
> synthetic Nitrogen sources, are tehse concerns still valid?
>
>  If the C content is very high, then N will be immobilized, if
>> it is very low, then it is likely to be very actively degraded and
>> localized heating can be expected.  Salts can also be a problem if the
>> materials are not mixed to dilute them with the surface soil or other
>> organic materials that are low in salt content.  So, know your materials
>> is the best bet.  Understand how they will behave as they decompose in
>> place and be sure that you do not inadvertently harm the system while
>> trying to preserve the nutrient content to feed the soil, rather than be
>> lost to the atmosphere.
>
> OK...
>>
> Del...
>
>
>>> On the other hand, composting "in place" does end up with more "in
>>> place energy availability". The first question is: Is this potential
>>> energy available to the plant, or does it simply get consumed by the
>>> "in-place
>>> composting bacteria", with no direct benefit to the plant?
>
>>the latter
>>>
>>> The next question is: It there any way to prevent the "in-place
>>> composting process" from temporarily depleting the Nitrogen that would
>>> otherwise have been available for plant growth?
>
>> yes, by keeping the
>>> C:N ratio overall not too much higher than 20:1, which is the
>>> theoretical tipping point between N immobilization and N mineralization.
>>>
> OK!! This would seem to be why Dr. Karve's "sugar feed" works... a
> relatively small anount of relatively available carbohydrate stimulates
> the soil bacteria, and there is not enough to tie up nutrients.
>
>>> One obvious solution to the Nitrogen Availability problem might be to
>>> ensure the raw materials had adequate Nitrogen to permit "self
>>> composting" ingredients to compost in-place, without the need for
>>> temporarily robbing Nitrogen from the plant.  Indeed  However, all
>>> that this might accomplish would be a "self fueled fire". The
>>> ingredients would have no need to interact with the Soil, and rob its
>>> nitrogen.
>
>> Not sure what you mean here
>>>
> Dr. Karve suggests there is a significant benefit to "composting in
> place", in contrast to composting the feeds externally, and adding the
> compost. If there was a "perfect mixture of materials for composting,
> there should be no addition to, or draw from, the soil during the
> composting process. What I am missing is an insight into why composting
> in place is an advantage.
>
>>> On the other hand, your "Sugar Fertilizer" procedure seems to work
>>> wonderfully, and no Nitrogen is added to the Soil... only energy for
>>> the plants.
>
>> This is not energy for the plants as explained above
>>>
> Poor explanation on my part... what I meant to suggest was that Dr.
> Karve's sugar process adds a very small amount of carbohydrate, not
> enough to tie up sufficient Nitrogen to stress teh plants.
>
>>> Is it perhaps a case of "too much of a good thing is a bad thing?" One
>>> can see that too much cellulostic plant material with a high C/N ratio
>>> added to the soil could possibly deplete N from plants, but if a smaller
>>> amount was added, there might not be enough cellulose to deplete
>>> existing soil N to retard plant growth over the short term.
>
>> Indeed
>>>
>>> So we seem to get back to the first question: Could you please explain
>>> how the release of energy from "in-place composting" is more
>>> beneficial to the "Soil Food Web" than would be the addition of the
>>> same material
>>> that was composted externally?
>
>> The answer lies in doing 'in place
>> composting' correctly, aiming to not lose your N (and S) to the
>> atmosphere, but keeping it in organic forms, such as living microbial
>> biomass that is recycled on a short time scale.
>>
>> Hope this helps.
>>
> I am still missing something. I still cannot see why composting "in
> place" would offer any advantage over external composting, assuming
> there was a good mix of ingredients to be composted.
>> Janice
>>
> Thanks again!
>
> Kevin
>
>>
>>> Thanks!!
>>>
>>> Kevin Chisholm
>>>
>>> adkarve wrote:
>>> > Dear Juergen,
>>> > Do not apply compost to the soil.  On the one hand, agronomists tell
>>> us to
>>> > apply organic matter to the soil in order to feed  the soil
>>> micro-organisms,
>>> > but on the other hand, they ask us to compost the biomass before
>>> applying it
>>> > to the soil. The nutritional value of the biomass is lost in the
>>> process of
>>> > composting. Also, while recommending the dose of compost to be 
>>> > applied,
>>> > agronomists calculate it according to the N.P and K content of the
>>> compost
>>> > and not according to the nutritional calories in the compost. We
>>> found in
>>> > our experiments that non-composted green leaves, applied at the rate
>>> of 125
>>> > kg per ha, once every 2 to 3 months, gives as high yield from crops as
>>> > application of recommended doses of chemical fertilizers.  Even in
>>> the case
>>> > of dung, we found that relatively small quantities of dung are highly
>>> > effective, if the dung is applied in the raw and non-composted
>>> form.  Dung
>>> > consists partly of lignin (which can be digested neither by 
>>> > herbivorous
>>> > animals nor by the anaerobic bacteria in their guts) and partly of a
>>> large
>>> > number of bacteria. Both the lignin and the dung bacteria serve as
>>> food for
>>> > the soil bacteria. By composting dung, we unnecessarily rob the soil
>>> > micro-organisms of nutrition.
>>> > Yours
>>> > A.D.Karve
>>> >
>>> > ----- Original Message -----
>>> > From: Juergen Botz <jurgen at botz.org>
>>> > To: <terrapreta at bioenergylists.org>
>>> > Sent: Wednesday, April 18, 2007 5:45 PM
>>> > Subject: [Terrapreta] Greetings
>>> >
>>> >
>>> >> Hello, all.  I just joined the list, glad to see it so lively!
>>> >>
>>> >> To introduce myself... about a year ago I acquired a small farm
>>> >> in coastal Bahia, Brazil.
>>> >>
>>> >> The land is 2/3 secondary growth Atlantic rain forest, the other
>>> >> 1/3 is partially planted with coconut palms and pineapple, plus
>>> >> various fruits and plenty of manioca.  Unplanted areas that
>>> >> aren't forest are heavily overgrown with dense brush.  The
>>> >> subsoil is nutrient-poor loam, often highly compacted.  In most
>>> >> spots there's a layer of anywhere from an inch to a foot that
>>> >> has a significant amount of organic matter, and yes, quite a bit
>>> >> of charcoal.
>>> >>
>>> >> The charcoal doesn't seem to have been deliberately incorporated...
>>> >> rather, the area has been cleared by fire a couple of times in
>>> >> the past and because of the high humidity here that leaves a
>>> >> lot of charred matter.
>>> >>
>>> >> I am experimenting with various natural farming and permaculture
>>> >> techniques here, and my main goal right now is to get the soil
>>> >> in better shape.  That means breaking up the compacted subsoil,
>>> >> adding organic matter, adding more charcoal to stabilize it and
>>> >> reduce future compaction, planting various leguminous trees and
>>> >> ground covers, and of course building up a layer of humus.
>>> >>
>>> >> I have a source of humus and wood for charcoal in the forest.
>>> >> I've also been making large quantities of compost from a mixture
>>> >> of wood- chips, manure, and seaweeds raked up at the beach.  I'm
>>> >> thinking of adding charcoal to this mix right from the start of
>>> >> composting.
>>> >>
>>> >> One of the things that led me to this list was that I was
>>> >> scouring the Net for info on small-scale charcoal production.
>>> >> I found a bunch, and I found this list.  I think I'll be trying
>>> >> some pit-kiln variation shortly, and in the longer run I may
>>> >> build something like the adam retort.
>>> >>
>>> >> :j
>>> >>
>>> >>
>>> >> _______________________________________________
>>> >> Terrapreta mailing list
>>> >> Terrapreta at bioenergylists.org
>>> >>
>>> http://tech.groups.yahoo.com/group/biochar/
>>> >
>>> >
>>> > _______________________________________________
>>> > Terrapreta mailing list
>>> > Terrapreta at bioenergylists.org
>>> >
>>> http://tech.groups.yahoo.com/group/biochar/
>>> >
>>> >
>>>
>>>
>>> _______________________________________________
>>> Terrapreta mailing list
>>> Terrapreta at bioenergylists.org
>>> http://tech.groups.yahoo.com/group/biochar/
>>
>> *****************************************************************
>> Janice E. Thies
>> Assoc. Professor of Soil Biology
>> Director of Graduate Studies
>> 719 Bradfield Hall
>> Dept. of Crop and Soil Sciences
>> Cornell University
>> Ithaca, NY  14853
>>
>> phone 607-255-5099
>> fax    607-255-8615
>
>
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