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  • From: "Krystle Chung" <learning@selfmadefarmer.com>
  • To: permaculture <permaculture@lists.ibiblio.org>
  • Subject: Re: [permaculture] Dry farming [Fwd: [SANET-MG] soil's influence on transpiration]
  • Date: Sat, 12 Jan 2008 23:16:48 -0700

Lawrence,

If you haven't already, check out "The Drought Myth" by William A. Albrecht.
Here's a link to the two page PDF:

http://www.acresusa.com/toolbox/reprints/droughtmyth_nov00.pdf

It discusses the relationship between soil fertility and the effect of
drought on the frequency and severity of crop failures. I'm in NM at the
time and I found it very interesting; you might, as well.

Best,

Krystle
http://www.selfmadefarmer.wordpress.com

On Jan 12, 2008 9:55 PM, Lawrence F. London, Jr. <lflj@intrex.net> wrote:

> -------- Original Message --------
> Subject: [SANET-MG] soil's influence on transpiration
> Date: Sat, 12 Jan 2008 17:05:03 -0700
> From: Edna Weigel <eweigel@CABLEONE.NET>
> To: SANET-MG@LISTS.IFAS.UFL.EDU
>
> A friend convinced me to read John Jeavon's "How to Grow More
> Vegetables..." It's extensive bibliography includes John A. Widtsoe's
> 1919
> "Dry Farming." On http://books.google.com/books I found Widtsoe's 1910
> "Dry Farming: a System of Agricultures Under a Low Rainfall" in free
> downloadable .pdf format which I found very interesting.
> I had always regarded transpired water as something over which I had no
> control if I wanted to grow a particular crop. However, Widtsoe quotes
> study after study in which fertilized soils or well-cultivated soils or
> previously summer fallowed soils produce on the order of twice as much dry
> matter per unit of water transpired as controls. That's impressive and
> especially important for growers like me in arid lands with falling water
> tables! There are brief hints that the addition of (as sodium nitrate) or
> formation of nitrates (enhanced by cultivation) makes the difference.
> These questions come to mind:
> 1) Have these observations from a century ago stood the test of time?
> (Enough studies were quoted to convince me the effects were real.)
> 2) If the answer to #1 is affirmative, why, in these days of global
> warming
> and drought and overdrafted aquifers and no-till methods is this
> information
> not more widely known? (I can't believe I'm the last person to learn
> this.)
> Could this relate to the cheapness of chemical fertilizers?
> 3) Could the numerous anecdotal stories (plus some careful experiments)
> showing the value--especially in drought conditions--of compost and other
> soil organic matter relate to the form (nitrate vs. ammonium) of nitrogen
> in
> the soil with or without added compost?
> My understanding of the chemistry of nitrogen compounds in the soil is
> sketchy, but it passes my common sense test that an aerated soil would
> tend
> to have more nitrate relative to ammonium ions when compared to a compact
> or
> water-logged soil. I don't have a feel for the effect of organic matter
> on
> the nitrate/ammonium balance. It also passes my common sense test that
> plants will transpire more water (until they get enough nutrients to carry
> on their life processes) if the water they take up from the soil doesn't
> contain adequate amounts of nutrients.
> I hope one or more SANETer(s) can enlighten me on transpiration and
> ways
> of maximizing crops while minimizing water loss.
> Regards,
> Edna
>
>
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