perennial crop modelling

[Mary Milne]

Dear colleagues,

I am working on a dynamic simulation model for cocoa production in PNG. Has
any-one come across a perennial crop supply model using a systems dynamics
framework rather than the standard econometric approach?


Regards,

Mary Milne


_________________________________________________________________________

Mary Milne
Department of Agricultural and Resource Economics
University of New England
Armidale
NSW 2350
AUSTRALIA

Fax: (067) 733281
e-mail: mmilne@metz.une.edu.au

["William Steinhurst"]

Does the term "perennial" in your question simply relate to the fact
that being a tree, cocoa is biologically a perennial, or do you have
in mind a model for sustainable yield, or is there something else
intended?

Bill Steinhurst
From: "William Steinhurst" <wsteinhu@psd.state.vt.us>

[Jennifer Cover]

I tried this link:

>Try contacting Wouter Gerritsma at:
>Wouter.Gerritsma@USERS.AGRO.WAU.NL
>and on the web: http://www.spg.wau.nl/agro
esearch/pps05abs.htm

and got an error message (wrong server). Here is the address I found:
http://www.agro.wau.nl/agro
esearch/Pps05abs.htm

Jen Cover

Modeling Consultant
__________________________
Address: Powersim AS, P.O. Box 206, N-5100 Isdalst=F8, Norway
Internet: jenco@powersim.no
Web page: http://www.powersim.no
Phones: +47 56 34 24 46 (Work); +47 56 34 24 00 (Secretary);
Faximile: +47 56 34 24 01 (Work)

[Mary Milne]

William,

I was referring to cocoa as a perennial crop in the biological sense.
However, I am interested in modelling sutainable yields, given the climatic
and soil data that we have available and incorporating it into production
functions for smallholders and estates in Papua New Guinea.

Mary Milne

_________________________________________________________________________

Mary Milne
Department of Agricultural and Resource Economics
University of New England
Armidale
NSW 2350
AUSTRALIA

Fax: (067) 733281
e-mail: mmilne@metz.une.edu.au

[John Sterman]

Besides Dennis Meadows classic "dynamics of commodity production cycles",
see Helmut Weymars "Dynamics of the World Cocoa Market" (19668, MIT
Press). Weymar did his phd thesis in economics but worked with the MIT SD
group; his model is basically a system dynamics model of the supply side of
the market which for which he then estimates the parameters.


John Sterman

MIT Sloan School of Management
E53-351
30 Wadsworth Street
Cambridge, MA 02142
617/253-1951 (voice); 617/258-7579 (fax), jsterman@mit.edu
http://web.mit.edu/jsterman/www

[rjrahn@microtec.net (R. Joel Rah]

Possibly Dennis Meadows book Dynamics of Commodity Cycles would be of some
help for your commodity crop. It should be available in a university library
or from Progress Press.

Good luck!
R. Joel Rahn
From: rjrahn@microtec.net (R. Joel Rahn)

[rn_kickert@ccmail.pnl.gov (Ronal]

Try contacting Wouter Gerritsma at:
Wouter.Gerritsma@USERS.AGRO.WAU.NL
and on the web: http://www.spg.wau.nl/agro
esearch/pps05abs.htm
for information about his CASE2 simulation of cocoa growth and production. He
is with the Dept. of Agronomy, Wageningen Agricultural University, Netherlands.
The model is not implemented in the usual systems dynamics software
environments, but given the paucity of tropical crops simulations, at least you
can convert this to your favorite S.D. software if you so desire.

Ron Kickert
Battelle Pacific Northwest
Richland, Washington
From: rn_kickert@ccmail.pnl.gov (Ronald N Kickert)

[Jim Hines]

A further addendum to Johns note on Helmut Weymar.

Helmut Weymar went into commodities trading following his work at MIT in
system dynamics. He became one of the most successful commodity traders
ever. His sd work on commodities might indeed be worth a look.

Jim Hines
MIT
JimHines@interserv.com