[compost_tea] Re: Sawdust in compost tea

From: dblsixteenout <jseegert_at_yahoo.com>
Date: Sun, 06 Mar 2011 17:12:56 -0000

It is generally acceptable to use sawdust and wood chips as a component of =
compost. However, care should be taken when choosing the wood source. Firs=
t and foremost, never use black walnut since this tree emits a chemical tha=
t will prohibit plant growth. This is a type of defense against weed and c=
over growth inhibiting sapling growth. The other type of wood that should =
be limited is oak or other woods containing high levels of tannins. These =
tend to contain tannic acid and if used in higher quantities will raise the=
 pH of the compost resulting in detrimental effects on the microorganisms. =
 Most of us don't have access to oleander but this also emits a deadly toxi=
n that should not be used around gardens intended for human consumption. Al=
so, plywood sawdust should be steered clear of since the chemicals that are=
 used in the resins are typically not intended for human consumption.

Wood fiber is high in carbon (200:1 C:N) content and is best used as topica=
l application (10 tonnes/acre or about 4.5 lbs per 100 square foot) but wil=
l definitely lock up a good portion of Nitrogen in the compost since the ty=
pe of organisms that break down cellulose will also demand Nitrogen. If us=
ing wood fiber in compost, you must add about 14 oz of blood meal (_at_11% N) =
or 2 lb of a 5% N granular product per 20lbs of wood fiber to offset the am=
ount of N used to compost it (this is equivalent to about 10 lbs of N per t=
onne of sawdust). One good source of N to add with sawdust is poultry manur=
e. This is a great way to "cool" down this type of waste.

Another option is to boost the level of N before adding the sawdust by addi=
ng food sources to the worm pile that results in a compost that contains en=
ough N for the cellulose consuming organisms and allows for an adequate lev=
el of N left after the sawdust is decomposed.

If you are going to use this sawdust mixed compost for ACT without adding a=
ny additional Nitrogen source, remember that making a bacterial based ACT u=
tilizing sawdust blended compost will continue to consume any nitrogen from=
 the compost. Allowing the mix to run longer to propagate a significant lev=
el of bacterial organisms to feed the protozoa and other N-producing organi=
sms, will allow the bacteria consuming organisms to resupply the levels of =
available/free N as a byproduct. In other words the propagation of Bacteri=
a is dependent upon the consumption of available/free N in your compost. A=
llowing significant levels of bacteria to develop will allow the protozoa a=
nd other N generating organisms to increase in numbers. This allows the org=
anisms breaking down the cellulose a source of N but should also leave enou=
gh availble/free N for an effective tea.

The process is dependent upon the types of compost, additives and times of =
brewing but can easily be confirmed by microscopic evaluation (making sure =
there are high levels of bacteria at first and then protozoa).

If your intent is only to allow the vermicompost to be easily handled, reme=
mber that any compost will easily dissolve in the brewer regardless of its =
consistency and how it is added. It sounds like there might be a concern wi=
th storing the "wet" vermicompost until it can be used for ACT (possibly tu=
rning anaerobic). Consider allowing the soil to sit in an open container or=
 spread it out until the desired moisture content is satisfactory for stora=
ge.

Also, wood fiber will take longer to compost 6 months - 1 year depending on=
 the size of the wood fiber.



--- In compost_tea_at_yahoogroups.com, Cameron Jenkins <milkman_at_...> wrote:
>
> Hi all,
>
> Been a lurker for a month or so, but this is my first post.
>
> I live on a small suburban block in Melbourne, Australia. I have a number=
 of worm farms, two of these are can-o-worms. They work well for me, except=
 the castings in the bottom tray always seems to be quite wet and the casti=
ngs are all clumpy and not really suited for the 44 gallon drum I brew my c=
ompost teas in.
>
> Today, I emptied the bottom tray out of one of the can-o-worms, and mixed=
 it with some non treated sawdust. As the sawdust drew in some of the moist=
ure, it allowed the worm castings to break apart into smaller bits. I then =
used a sieve to sift the castings to use into my compost tea.
>
> So the question is, how would sawdust go in a compost tea? I'll only be a=
dding some molasses and fish emulsion to my next brew, so I'd be interested=
 in feedback as to whether there would be anything wrong with sawdust mixed=
 with fine worm castings would go in a brew.
>
> Regards,
> Cameron Jenkins
>




Received on Sun Mar 06 2011 - 13:17:44 EST

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