Healthy soil and sustainable growing

[Dieter Brand <diebrand@yahoo.com>]

Paul,

 

My use of the term subsoil may have been a bit too liberal. I guess, I should

have said the lower part of the topsoil. There is probably a technical term

for this. Anyway, my intended meaning was that layer, in undisturbed soil,

where permanent humus can be stored under anaerobic conditions for a long

time, and which is covered by a few inches of aerobic topsoil where organic

material is broken down under aerobic conditions, but which is not yet stable

humus, even if it looks nice and black. In traditional agriculture, the inversion

of these two layers by ploughing is the principal cause for the loss of natural

soil fertility. Subsoil ploughing doesn’t of course turn the soil. I was just

curious about the effect of subsoiling on the permanent humus in this layer.

 

David,

 

I can’t judge the merit of the Keyline subsoiling since I don’t have any

direct experience with this. And I don’t know in which way the Keyline

marketing is involved with the Carbon Farmers scheme. Anyway, both

seem to emphasize grass land as the best way for soil-improvement and

CO2 sequestration. The Carbon Farmers site even has a page (which

I didn’t read) with selected quotes to argue against reforestation.

This seems to be indicative of a narrow commercial focus rather than

a broad environmental concern. I have nothing against making money,

but we have to be honest about it.

 

I will take your word that the Keyline subsoiling has improved the soil

in many cases; however, different applications and conditions (soil,

climate, etc.) require different strategies. In my case (semi-arid

climate and clay soil), I found that the best way to improve the soil

is to feed it a varied diet consisting of green annuals together with

woody perennials (including brambles, shrubs, bushes and trees),

and let the roots do the subsoiling.

 

Regards, Dieter

David Inglis <mhcsa@verizon.net> wrote:
> > Nobody has evidence that subsoiling sequesters CO2.
> +> There's no significant humus in the subsoil, but if there were then
> aerating - >oxidizing it - would release CO2 to the atmosphere.
> Really. If this was what was being done this would be correct. There is
> always some turnover of Humus, the point is whether there is ultimately a
> net gain or net loss of OM to the soil. Strictly speaking this is correct in
> that the definition of subsoil is that
>  it is below the 'living layer' layer
> of the topsoil. Therefore even if one doubles or triples the topsoil layer
> your statement is technically correct. One of the objects of the Yeoman
> Keyline approach is to dramatically increase the depth of the topsoil layer
> [A horizon] by transforming the subsoil [B Horizon]. Yeoman worked
> extensively with the Australian University system in the 50's and 60s to
> assess the impact of his approach. I have personally witnessed increases in
> 'total' soil OM [organic matter] through the use of Keyline ploughs in
> conjunction with pastures or short term Leys. I have also seen the misuse of
> the tool reduce total OM.
> > >With 18 to 24 inches, the Keyline subsoilers go deep into the subsoil, it
> is hard to > imagine that grass roots go as deep as that. 
> That is the point; to get roots to colonize areas of the soil previously not
> open to them. Many pasture species will go way deeper than 18" -24". By
>  the
> way, the effect of Keyline plowing also goes way beyond the actual depth of
> plowing.
> > > Also, in relation to the Carbon Farmers claims, is the improved growth
> really due
> > >to the sequestration of CO2 from the atmosphere? Or is it due to the
> aeration of the permanent humus in the subsoil?
> The atmosphere, though a little of the "permanent humus in the subsoil" is
> initially oxidized. 
> > > Claiming carbon credits for CO2 sequestration while in reality burning
> > >the carbon accumulated in the permanent humus decades ago can hardly be
> right.
> I believe carbon credits should only be given for total increases of OM
> through the whole soil profile not just the top 6". I also believe if
> Farmers are to paid for this sequestering then they should also pay for
> burning it up. I can not imagine a scheme like this working well under our
> current world leadership who can't even 'run a bath' let alone a
>  program
> that rewards a global benefit. For it work it would have to be based on
> atmospheric CO2 exploitation; we know how to exploit.
> > > And how do the Carbon Farmers account for the fuel you need to subsoil
> grazing
> > > land with very powerful machines, an external input normally not
> required for > >grazing land. 
> The same way we always have, by the increased production. Anyone not
> familiar with the design of the Yeoman Keyline plough should know that it is
> not a conventional subsoiling plough, which does require high HP, nor is it
> used the way a normal subsoiling plough is used. The power requirements are
> 12HP for the first shank and 8HP for each additional shank, a lot less than
> any other subsoiling plough I know of. I pull mine with a 23HP tractor. Also
> as the soil develops under Keyline management it ploughs easier. The action
> is very gentle and if it not then the operator is at fault.
> The bottom line is
>  that the big difference with Yeoman is not in the plough
> but in his thinking. He believes that Humankind can have a beneficial effect
> on soils and their rapid development. Yeoman does not physically prepare the
> tilth of the soil with his plough but acts as a facilitator of the
> development of the soil life. This is not currently PC but it does work,
> though it takes longer in a continental climate than in his native Australia
> which has the potential for year round soil development. I would say 6 not 3
> years.
> David Inglis
> Mahaiwe Harvest C.S.A.
>
>
>
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