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<DIV><FONT face=Arial size=3>APWG: </FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>While I strongly smell a certain odor here, I must admit
that I have used my nose in practice, but only to a limited degree and for
limited and often preliminary way. Dogs and hogs have long been used to sniff
out underground "fruiting bodies" of certain mycorrhizal fungi, and this might
actually be possible to assess the presence or absence of certain symbionts,
know of no studies in this regard. Anybody? </FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>The strong odor of anaerobic conditions can
sometimes easily be detected by most human noses, and different compounds
and elements certainly have distinct odors. There may be untapped potential
here, but again, I am aware of no studies that verify the validity of smell
tests. </FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>There is, however, plenty of folklore. I grew up on a
stock-farm, and my father and others commonly sniffed soil to "judge" its
quality. </FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>I don't doubt that there is a difference in the odor of
"dead" versus living soils, particularly when organic matter is absent. But the
absence or paucity of humus below the A-0 layer indicates that something more
than a weed invasion is part of the soil's past. But again, context is
everything, and that includes time. Soils lacking humus are usually either arid
in the extreme or areas where the biological/living soil has been physically
removed, not that "aliens" have taken it away. </FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>Such "dead" soils are more likely to support weeds than
indigenous species because the site conditions and the genetics of the (weed)
plants growing thereon match those conditions--in toto. </FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>There's more than soil, however, that minimizes the
recolonization of disturbed sites by indigenous species. In time--perhaps a very
long time--indigenous species usually do re-colonize such disturbed sites--when,
and only when, all relevant conditions for their survival and reproduction are
present. </FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>I have seen, for example, tiny pioneer populations of
indigenous grasses gain a foothold in the midst of a large acreage of
"dead" soils "full" (or so I thought at first) that had lain fallow (no
livestock) for several years. Who knows what made this possible? Perhaps an
animal had a seed caught in its fur, and perhaps another animal transported a
mycorrhizal spore at the right place and time under the right conditions for
their unification--who knows? But it happens. Once that plant is able to survive
fatal predation and set seed, those seeds can then fall upon much more favorable
conditions (e.g., presence of mycorrizal fungi), and the colony can then receive
pollen from perhaps distant populations of the species. Time and distance can be
major factors, among countless others. </FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>N-fixing bacteria may work for or against recolonization
by indigenous species. Too much N almost always means weed dominance.
</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>The truth probably is that we still know far too little
about the complex phenomena involved, but every effort to sniff them out is
worth a try. However, we should never be so cocksure of our conclusions that we
stop learning. </FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>WT</FONT></DIV>
<BLOCKQUOTE
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=rlb14@cornell.edu href="mailto:rlb14@cornell.edu">Robert Layton
Beyfuss</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=craig@astreet.com
href="mailto:craig@astreet.com">craig@astreet.com</A> ; <A
title=apwg@lists.plantconservation.org
href="mailto:apwg@lists.plantconservation.org">apwg@lists.plantconservation.org</A>
; <A title=craig@ecoseeds.com
href="mailto:craig@ecoseeds.com">craig@ecoseeds.com</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Tuesday, September 24, 2013 3:56
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [APWG] Smell soil to see if
you have dead soil causing weeds?</DIV>
<DIV><BR></DIV>
<DIV
style="FONT-SIZE: 10pt; COLOR: #000000; DIRECTION: ltr; FONT-FAMILY: Tahoma">
<P>I doubt if grant funders will provide restoration money based
on smelling the soil. Dogs can be trained to smell certain cancers. Maybe
we can hire them. Is there really any data regarding minimal nutrient
thresholds for native plants? We have known for years that nitrogen is a
tricky element to measure because it likes to quickly change forms from
ammonia to nitrate, nitrite, etc . Any nitrogen measurement is a snapshot
of a moment in time. Phosphorus is also turning out to be a tricky character
due to mychorizzae. I have University lab soil test results from soils that
list 0 pounds per acre of P, yet these soils are covered with healthy forests.
</P>
<P> </P>
<DIV style="FONT-SIZE: 16px; COLOR: #000000; FONT-FAMILY: Times New Roman">
<HR tabIndex=-1>
<DIV id=divRpF686644 style="DIRECTION: ltr"><FONT face=Tahoma color=#000000
size=2><B>From:</B> APWG [apwg-bounces@lists.plantconservation.org] on behalf
of craig@astreet.com [craig@astreet.com]<BR><B>Sent:</B> Tuesday, September
24, 2013 4:24 PM<BR><B>To:</B> apwg@lists.plantconservation.org;
craig@ecoseeds.com<BR><B>Subject:</B> [APWG] Smell soil to see if you have
dead soil causing weeds?<BR></FONT><BR></DIV>
<DIV></DIV>
<DIV>
<P>Dear All,</P>
<P>I am going to suggest an even easier test to check for soil problems that
can cause weed infestations--is to smell the soil?</P>
<P>Where I have the worst weed problem at my site in Palo Alto, the Italian
thistles and the medusa head grass, I noticed that when I dug up the soil for
the soil nutrient tests on those sites, there was no visible organic matter
below the weed thatch, and there was no smell to the soil. The soil is
dead, nobody microscopic like the fungi and yeasts, alive any more.</P>
<P>Then if you go 20 feet away where there is no medusa head or Italian
thistles, when you dig past the surface thatch, you can see visible organic
matter, and if you breathe in, you can sniff that somebody is still home in
that soil. </P>
<P>I am suggesting that along with soils being below the nutrient threshold
for native seedling survival can cause weed infestations, that you can also
have a case of weeds as symptoms of dead soil. The weeds could be looked
like flies gathering on a dead body, and we may need to resurrect the soil
microbes in order to chase away the weeds?</P>
<P>Sincerely, Craig Dremann (650) 325-7333</P>
<P> </P></DIV></DIV></DIV>
<P>
<HR>
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