Hi Arjan,

Thank you for your informative response. I meant to email to the
DSSAT list server. Sorry.

Let me ask you more about Q2. I am interested in changing composition
(CARB, CELL, LIGN) and decay rate constants of fresh organic matter
(FOM) such as cover crop residue or maize residue and cattle compost
for simulating short-term N dynamics (14 months) in bare fallow. If I
want to compare model predictions between versions 3.5 and 4.0 after
the incorporation of FOM or compost, do I need to conduct following
steps?
  1) Prepare a FileX.
  2) Put measured or estimated parameters in SOILN980.SOL for version
3.5 and in SOILN040.SOL for version 4.0.
  3) Go to CropTest to conduct simultaneous runs of version 3.5 and
4.0. Where can I choose FileX prepared for CropTest?

Best,

Hiroshi

>2.  One of the major differences between v3.5 and v4.0 is that the
>latter has a new SOM/residue module that was based on the CENTURY
>model (see: Gijsman et al. 2002 Modifying DSSAT for low-input
>agricultural systems, using a SOM/residue module from CENTURY.
>Agron. Journal. 94:462-474). The original SOM/residue module of
>DSSAT is also still included, so that who did many simulations with
>v3.5 does not suddenly get different results with v4.0 (the two SOM
>modules do give quite different results, as shown in Fig. 5 of the
>article).
>
>The file SOILN980.SOL only serves for the original module. In v4.0
>this file has been updated and is called SOILN030.SOL. If you want
>to change some parameters of the CENTURY-based module, then you have
>to go to the file SOMFIX_C.SOL This has many parameters (about 130)
>but no parameter explanation (we should add that).