[Gasification] recydling ash vs. removing fuel

[Pels, J.R. (Jan)]

Dear list,

I agree with Kevin's statement:
> There is no question that synthetic fertilizers and pesticides work. 
> People have been doing this for decades

You can grow tomatoes on rock wool with substrates, etc. Fertility
exists only as long as nutrients are supplied from external sources.
However, this is not the ONLY way nutrients can be supplied to growing
plants. You can recycle them from the unused parts of the harvest, and
adds only mineral fertilizers to compensate for the remaining losses.
Both approaches are valid. And anything in between.

Carbon-rich humus can also store and release nutrients. Kevin is right
in his objection against Leland's statement:
> > Carbon conversion in the soil requires micronutrient 
> supplementation 
> > to support the microbes which depletes the slowly available 
> > micronutrients.
> As I understand it, the microbes and fungi are conduits that 
> take the nutrients from the mineral soil, and make it 
> available to the plant. 

It is clearly false. It leaves the impression that that microbes take
away nutrients and absence of microbes leaves them available for crops.
The opposite is true for water soluble nutients (in particular K). It is
leached rapidly if no life forms exists in the soil to retain it.
Unfortunately such errors cast doubts on the other statements. Another
example that makes you wonder:

> >  A major
> > issue is that the insoluble phosphate found in organic matter 
> > accumulates in the upper layers of the soil and prevents other 
> > elements from moving into the root zone, also hardens the 
> surface of 
> > the ground over time by cementing with other elements.
> That is the case with excessive application of feedlot 
> manure, but I don't think it is the case when the manure is 
> applied at reasonable levels. 

Leland claims that "insoluble phosphate found in organic matter [...]
hardens the surface of the ground". Hardening of the ground is typically
the result of heavy machinery not of overloads of phosphates. My country
has excessive amounts of P in the ground enough to go decades without
P-fertilizer. The result of decades of manure spreading, but the surface
of the farm lands is definitely not hardened. What adds to hardening is
absence of worms and other life forms that keep the soil airy. 

The third example:
> > Ash is a better fertilizer than plant matter and can be 
> seen after a 
> > fire on how fast plants regrow.
> >   
> And what about the following years? If there is insufficient 
> organic matter present in teh soil, there is a strong 
> likelihood that the excess nutrients will get leached away.

Ash is only better if you count the fast regrowth after a fire. Slash
and burn is the equivalent agricultural technique. Typically after a few
years, the soil is exhausted and new land needs to be burned. The
mineral fertilizer (ash) causes fast growth, but only as long as it is
supplied. 

If Leland were a fertilizer producer/seller I would accuse him of
spreading false information. I know he has a clear and specific vision
on nutrient management and I know that it applies to a certain type of
soils. His vision does not apply worldwide. Recycling plant matter can
keep fields active indefinitely, but not producing at its maximum. This
may or may not be true for different climates/soil types. And that is
probably the key stone in this discussion. 

What remains is the question how much of the residues can or should be
used to restore the carbon balance in the ground. I am researching this
subject in a framework of sustainable biomass production. What I know
now is, that it differs from crop to crop and from acre to acre.
Opinions vary widely - also outside this discussion list - from: "no
carbon recycling is needed in the ground" to "all leftovers should be
composted and returned". Even the Agricultural University of the
Netherlands, one of the top institute in this field, couldn't give me an
answer. They are working on it. I am going to visit the French National
Agricultural Research Institute to see what answers come from their test
fields. 

Another of my preliminary conclusion is that it depends on what you want
with your land. If you want to squeeze the maximum harvest, you pay for
mineral fertilizer and no recycling, straining the soil's capacity. If
you want to minimize adding fertilizer, you must maximize recycling, but
you are not getting the maximum harvest unless you resupply the minerals
los with that part of the harvest that was not recycled.

It's just the farmer's choice.

Kind regards,

Jan Pels