Hi Ayman,


You write that you will be working on a new water-balance model in DSSAT and
also will consider the soil evaporation. Wouldn't that be a good opportunity
to tackle the impact on the evaporation of a litter layer on top of the
soil, as well? The new DSSAT4, which is soon going to be released, has a new
soil-organic-matter/residue module based on the CENTURY model. This brings
with it the consideration of residue decomposition in a surface litter
layer, which was ignored in earlier DSSAT versions. But a litter layer on
top of the soil may have a big impact on the evaporation, particularly if it
is a thick layer, like e.g. with sugarcane trash. However, with the new
DSSAT4 this is still on the list of future dreams. I don't want to push you
in doing more that you have time for and don't know how easy/difficult this
is, but anybody familiar with this topic is welcome to jump in and fill this
gap.



Arjan Gijsman

Univ. Florida / Centro Internacional de Agricultura Tropical (CIAT), Cali,
Colombia



-----Original Message-----

From:  SULEIMAN AYMAN [mailto:[log in to unmask]]

Sent:    Tuesday, December 17, 2002 4:41 PM

To:      [log in to unmask]

            Subject: Databases



Dear Colleagues,



In the ICASA meeting last month in Indianapolis, it was mentioned that the
water balance of DSSAT4.0 is the same one that has been used in the older
versions. I among other colleagues have suggested that many parts of the
water balance need to be updated. For now, I will be working on adding new
modules for soil water redistribution. After I have done adding these
modules, I want to compare the performance of the new drainage and soil
evaporation models with the original ones. I have some data to do that but
looking for more. Please if you have or know of any good data set that I can
use in the comparison let me know.



Thanks for your cooperation,



Ayman