Healthy soil and sustainable growing

["TradingPostPaul" <tradingpost@riseup.net>]

There is always some nitrogen loss, and the longer it waits before composting 
the more loss.  Regardless of what a TV program claimed, frankly I doubt that 
any method can turn wood chips into actual finished compost in two months - 
unless they're shredded into finer particles first.  Another thought: if much 
of the carbon compounds are removed in a biogas unit, how much of the carbon 
is left for the compost? We do want those carbon compounds in the soil too, 
don't we?  I don't believe the New Alchemy people said what kind of "garden 
compost" they were comparing with the digested sludge. Without knowing the 
source and condition of the compost, the comparison isn't useful.  And a dry 
sludge end product should certainly have a higher percentage of nutrients per 
ton than fresh manure, due to moisture loss.  Pit composted manure would 
likely show the same nutrient increase per ton after drying.

One figure I haven't seen is how much usable methane can be produced from how 
many livestock, horses, cattle, etc. And how long it would take for a given 
biogas digester to repay it's initial cost, figuring in the labor involved. I 
suspect the low return is the reason we've never seen the numbers on payback. 
 Manure digesters have been experimental for a long time, and from what I've 
seen they're always subsidized one way or another, much like ethanol.  I'd 
like to see something showing it's practical for the small farmer in terms of 
investment and ongoing labor required.

paul, tradingpost@riseup.net
---------------
The outstanding scientific discovery of the twentieth century is not 
television, or radio, but rather the complexity of the land organism. Only 
those who know the most about it can appreciate how little we know about it.
   - Aldo Leopold in  Round River, 1933
*********** REPLY SEPARATOR  ***********

On 4/28/2006 at 12:26 PM Greg and April wrote:

>How do you figure that?    How do you think that nitrogen is removed?
>
>The nitrogen compounds stay with the liquid as ammonia mixes with the
>water.
>
>In fact IIRC, water will absorb gaseous ammonia, that is the concept
>behind
>the old "Icy Ball " and other ammonia / water absorption refrigerator
>systems.    Water in the first chamber absorbs gaseous ammonia, lowering
>the
>vapor pressure, then with the lower vapor pressure allows more liquid
>ammonia to evaporate thus cooling the second chamber.
>
>Most of the ammonia formed in a biogas unit, absorbs into the water/slurry
>in the unit.
>
>
>About 3 yrs ago, I saw a program on TV, about a bio gas unit, that
>recovered
>methane from manure, and the resulting liquid was still so rich in
>nutrients
>that they would shred aspen and mix the resulting chips with the liquid
>and
>compost it.    A mound of aspen chips 30ft high would reduce to finished
>compost in about 2 months.    If the liquid was not rich in Nitrogen,
>about
>all that would happen is that it would fungus ( take a very long time to
>break down ), not compost.
>
>
>It is true, that if you leave manure out, exposed to the weather, it will
>lose nitrogen through liquid evaporation and/or through leaching ( as seen
>if a bale of hay is left out in the open ), but, in the case of a biogas
>unit, the nutrient rich liquid is retained, and used elseware, after much
>of
>the carbon is removed, in the form of CO, CO2, CH4, you might lose a small
>amount of nitrogen, but, that part that you may lose is but a fraction of
>the total.
>
>
>The New Alchemy Institute ( Methane Digesters for Fuel Gas and Fertilizer
>)
>calculates that garden compost has from 1.4 - 3.5 % ( dry weight )
>nitrogen,
>while digested cow manure sludge has from 2.7 - 4.9 % ( dry weight )
>nitrogen and that jumps to 6.1 - 9.1% with digested hog manure.
>
>The fact that digested sludge has higher amounts of nutrients than compost
>( even compost made under cover so nutrients are not baked out by the sun
>and leached out by the rain, is backed up by The National Institute of
>Industrial Research ( India ).