Subject: Re: Historical Sources on Sustainability of Agriculture

From: [email-masked] (Jonathon D. Haskett)
Date: Sat, 13 Feb 1993 01:44:57 GMT

This was originally written as a reply to a posting by Chris
Overton (<[email-masked]>),
but in response to Thomas Bjorkman (<[email-masked]>)
I think it will partly explain the approach I am taking.

---
>However, unless I am seriously mistaken, I don't think a 
>study done with the tools historians would bring to bear 
>would shed much light on what constitutes a sustainable 
>agriculture.  On the other hand, a scientist (like an ecologist) 
>might be able to make some sense of the historical record, 
>especially if teamed with an archeologist.

I tend to think that you are placing historians and their tools
in an excessively narrow box, and I would refer you to the
work of William H. McNeil on disease, or Cleometricians such 
as Peter Laslett or Le Roy Ladurie of the Annal School.  
However, perhaps we can advance this part of the discussion 
by leaving aside debate about which department such a 
researcher should have their office in, and instead begin to 
specify which skills and approaches would be useful in such an 
investigation (a topic which I think is of greater mutual 
interest anyway). I agree that systems which failed will 
probably be most informative, and I tend to think first about 
what sources of information would be available, and the skills 
to use them follow. So for example a hypothetical study of 
failure of Mesopotamian agriculture might include:

*Soil cores to determine the stratigraphy of salinization.
*Pollen studies to follow the changes in vegetation.
*Archeological data on farming techniques and diet.
*Energy and nutrient budgets.
*Historical records of granaries, transportation,
  transactions) to estimate yields-productivity and follow
  their decline.
*Examination of literature or chronicles to try to determine
  cultural attitudes to land, nature and agriculture.
*Integration of these data sources into a coherent chronological
  picture reflecting the interplay of crop biology, salinization,
  population, social structure, wars, and cultural attitudes 
  toward nature to analyze the causes of systematic 
  agricultural failure. 

This is presented as a rudimentary example of how such a 
study might be implemented. 

>A couple of points:

>Arguments about entropy are not especially germane since 
>the earth is an open system at more or less dynamic 
>equilibrium over geological time.  Climate fluctuations would
>be more entertaining to consider.

Point well taken.

>An obvious prediction: Population density of humans 
>and domestic animals is almost certainly the single most 
>important factor in determining sustainability.

I'm not sure if I agree with this. An agricultural system 
could be sustainable, while certain population levels 
overshoot its productive capacity and cannot be maintained. 
Bluntly, famine occurs but the system continues. Certainly 
population is often a determinant factor, but not always. 

Answers to Questions:

>Do you consider American intensive agriculture as practiced 
>in the mid-west sustainable?

Whether a current system is considered sustainable depends on which
assumptions are operative (i.e. is petroleum a finite 
resource), that is why these assumptions need to be made 
explicit and the sequence of reasoning needs to be visible:
i.e. I believe that petroleum is a finite resource. I believe that
our American intensive agriculture is greatly dependent on
petroleum. Therefore to the extent that the agricultural system
is dependent on petroleum it is not sustainable. So 1st step is 
to make assumptions explicit then proceed with analysis.

>Is there anything in the historical record that can contribute 
>to our understanding of the impact of the massive loss of 
>ground water?

Areas in which desertification has progressed might have some 
relevant historical information. However I do not know if 
irrigation by ground water has ever been practiced on the 
current scale before. It may be unprecedented. However, 
possibly examining records of well levels in Oklahoma during 
the dustbowl might provide a clue as to what happens when 
they are depleted. In addition the historical record could 
provide a general picture of the variety of ways in which 
societies have responded (successfully and unsuccessfully) to
the depletion of a resource on which they depend. This would
tend to throw light on the reasons why the massive loss of
ground water might continue or be halted, which is surely
relevant to its impact. 

>Could you remind me what the average rate of topsoil loss is 
>and the topsoil depth in the American mid-west?  Should I be 
>concerned about this?

The Soil Conservation Service publishes state maps showing the 
areas in which soil loss is considered to be excessive, and 
estimates of soil loss have been made for particular locations. 
However, I am not aware of regional or even state-wide 
estimates of average topsoil loss rates. The rate of topsoil lost is 
highly variable from site to site depending on the variables 
included in the USLE (Universal soil loss equation). Depth of 
topsoil is also highly variable ( I am confused by the term
topsoil, do you mean the plow-layer or the A horizon? for
purposes of this answer I will assume A horizon). Thus
an average value is difficult obtain and of questionable utility.
Since soils are not static entities but exist in a dynamic balance 
between formation and loss, the real questions have to do with 
relative rates: i.e. in how much of the land area of the midwest 
is the rate of loss of A horizon material due to erosion greater 
than the rate of A horizon formation. Where this loss exceeds 
formation, this represents a net loss of the soil resource, this 
troubles me and should probably trouble you. 

>Can you comment on salinization (or maybe its alkyloids, I 
>forget) in the San Fernando valley?  Is agriculture there
 >sustainable?

I am not sufficiently familiar with salinzation in the San 
Fernando valley to comment on it. However, the Coachela 
valley has also been experiencing salinzation. Essentially at this
location the irrigation has accelerated a the salinzation process 
which was occurring naturally. Excessive salt accumulations 
are now occurring in a matter of decades rather than a matter
of centuries. Remediation up until now has consisted of flushing
the soil by moving large quantities of water through the profile
to leach the salts below the root zone. However, this cannot
be continued indefinitely. Removing the salts by washing them
into the ocean is not feasible since significant concentrations 
of thallium and vanadium have been found, and it would be
unacceptable to move them offsite. Thus, it is certainly not 
assured that agriculture can be continued in the Coachela 
valley indefinitely. 

>How would you characterize Somalia and Haiti, to name just 
>two, in terms of the collapse of their agricultural systems? 

I don't know enough about either Somalia or Haiti to comment
on them, but a large part of my interest in this project was 
precisely to try to develop a method of inquiry which would 
yield meaningful information about the collapse of such
agricultural systems. 

>Here are situations where the interplay among overpopulation, 
>social conflict, agricultural depredation and maybe climatic 
>changes have contributed to ecosystem collapse. Again, I 
>think a historian would be hard pressed to sort this out 
>without considerable help from a scientist.

It seems to me that the interplay of overpopulation, social
conflict, and agricultural depredation are areas which have
traditionally been treated in great detail by historians. See
works on the late Roman empire as an example. Indeed one
may just as easily posit that a scientist might be very limited
in their understanding of these agricultural systems if their
knowledge is limited to a mechanistic understanding of the
the chemistry, physics and biology involved exclusive of the
history, attitudes and social forces at work.

I fail to see the utility of this heavy disciplinary emphasis. So
what if a person trained in one discipline necessarily has a
superficial understanding of another discipline. This is true for
everyone, since nobody can know everything. Surely a problem
such as agricultural sustainability needs to be approached from
several different disciplines, the trick being to usefully
integrate information and theory from all these disparate 
sources. 

(BTW I'm not a historian and I don't play one on TV.   ;-)       )

-----
I hope this clarifies some of my thinking about methodology
and the place of the proposed study. I might add that my
ideas on both these topics are still evolving. 

Jonathan Haskett
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From: [email-masked] (Chris Overton)
Date: 13 Feb 93 14:33:22 GMT

Jonathan,

Thanks for a very interesting discussion on an important topic.  One final
point --- in my own field, computational biology, interdisciplinary research
involving biologists, computer scientists and mathematicians is essential for
success.  My very strong impression is that your research effort would also
greatly benefit from an interdisciplinary approach, as does virtually any
study of complex systems (complex in both the common and technical sense of
the word).

I would very much enjoy seeing summaries of your work posted as you progress.
If you are willing (and I know this is asking a lot), I for one would like to
see short preliminary reports on whatever interesting observations you make.
(I won't be offended if you say no to that one.)

Chris

---

From: [email-masked] (Chris Overton)
Date: 13 Feb 93 14:33:22 GMT

Jonathan,

Chris

---

From: Thomas Bjorkman <[email-masked]>
Date: 15 Feb 1993 14:31:17 GMT

This doe slook like a very interesting approach.  I know that the
Mesopotamian situation is used as an example of the failure of irrigated
agriculture.  However, I certainly don't know if the social processes
that led to that failure are known.  Are they being repeated in
California, or have we wised up.

Another situation where the social processes are very imporant was
recounted by Garrison Keillor this week.  He was right on the money.  A
farmer in Lake W. had learned about a particular practice that was more
sustainable, planting no-till corn into a killed oat cover crop.  The
ideas behind it all made sense and he was convinced that it would work. 
But he did not want to be the first in Lake Wobegon to do it.  His
neighbors would make fun of him because it was out of the ordinary.

I think this situation arises a lot.  Even though the particular practice
has been proven many places, and is not particularly mysterious, it is
not adopted.  Agricultrual extension agents do a lot of what are called
demonstration and implementation trials for just this reason.  

Sorry to go off track from history to sociology, but I wanted to raise
another example where increasing the sustainablility of agriculture does
not depend on us biologists.