From sustag@beta.tricity.wsu.eduWed Apr  3 21:54:32 1996
Date: Wed, 3 Apr 1996 13:44:34 -0800 (PST)
From: "Tom Hodges (moderated newsgroup)" <sustag@beta.tricity.wsu.edu>
To: Principles of Sustainable Agriculture <sustag-l@listproc.wsu.edu>
Subject: Re: Request for help Cropwater Req. (fwd)



---------- Forwarded message ----------
Date: Wed, 3 Apr 1996 19:21:35 +0200 (MES)
From: "Thomas-M. Stein" <stein@wiz.uni-kassel.de>
To: sustag@beta.tricity.wsu.edu
Cc: gmazzari@espol.edu.ec
Subject: Re: Request for help Cropwater Req.

Dear Alby Aguilar,

>I am searching for the formula to calculate
>the evapotranspiration level on different crops,
>i also would like to know where i can find the
>Kc coefficient for different kind of crops.
>I hope you can help me but in case you can not
>i beg you to send me a mail list of people i cani
>ask for this information (specially Thomas Stein ).

There are a lot of formulas around to calculate / estimate
the (reference crop) evapotranspiration (ETo). Most commonly
used are probably the :

o	Penman
o	Penman-Monteith
o	FAO Modified Penman

I think a very good and practical (maybe the best) way to start to get
into this subject is to start with the following publications:

Doorenbos, J., et al, 1992:
Crop water requirements - guidelines for predicting crop water
requirements.-
Irrigation and Drainage Paper No 24, FAO, Rome, pp 144.
ISBN 92-5-100279-7

It should answer most of your questions.
It gives you a lot of Kc values for different crops as well.

Another publication which supplements that first FAO publication is:

Doorenbos, J. et al., 1986:
Yield response to water.-
Irrigation and Drainage Paper No 33, FAO, Rome, pp 193.
ISBN 92-5-100744-6

I don't know whether you have WWW access but maybe you want to try the
following pages on the IRRISOFT WWW Database on Irrigation and
Hydrology Software which contains quite a few computer program
descriptions (and some programs as well) which assist you in the
calculations.

The URL of IRRISOFT is:

http://www.wiz.uni-kassel.de/kww/irrisoft_i.html

Try the "Irrigation Management Programs'"- section

For example:

o  CROPWAT (Crop Water Requirements and Irrigation Scheduling)
o  CLIMWAT ( A Climatic Database for Irrigation Planning and
   Management)
o  CWR-VB (Crop Water Requirements for Windows)
o  DAILYET ( Daily Evapotranspiration)

DAILYET may be downloaded as well.

But still all those programs need an understanding of the theory like
described in the FAO 24.

I hope this was of some help to you.

Best regards

Thomas

______________________________________________________________________________

 Thomas-M. Stein
 University of Kassel (FB11)    Phone     : (+49)-5542-98-1632
 Dep. of Rural Engineering and  Fax       : (+49)-5542-98-1588
 Natural Resource Protection    Email     : stein@wiz.uni-kassel.de
 Nordbahnhofstr. 1a             WWW       : http://www.wiz.uni-kassel.de/kww/
 D-37213 Witzenhausen, GERMANY  List owner: IRRIGATION-L@listserv.gmd.de
______________________________________________________________________________

