Hiroshi,
 
The modified tipping-bucket water balance model used in the crop
models is somewhat sensitive to where you specify the layer
boundaries.  The thickness of the top layer is particularly important
because of its importance for controlling soil evaporation.  The
input module converts soil information to standard depths (0-5, 5-15,
etc., cm) and correctly averages all soil properties that vary with
depth.  The modified soil information correctly represents average
soil properties in the standard depth increments.  The total soil
depth is retained.  You can see the modified soil information in the
temporary input files (usually IBSNAT31.INP) that are created when
you run a model in DSSAT.
 
>    In answer to your first question, I think what you're referring to
>    is the
> mineralization factor SLNF found in the soil data file.  If that's
> true, then what you need to look for is DMOD in NTRANS because the
> value of SLNF is transferred to DMOD in the subroutine IPIBS.
>    Unfortunately, I can't answer your second question.
>    Good luck with your simulation.
> Sincerely,
> Richard
>
>
> At 04:40 PM 11/15/98 -1000, you wrote:
> >Dear DSSATers:
> >
> >Again, I have some questions about the DSSAT. I would be very happy if some
> >could kindly ask my questions.
> >
> >1) A user can change the N minalization factor to conduct a
> >location-specific calibration of the potential mineralization constant
> >(default = 8.3x10-5/day). But, I cannot find the N minalization factor in
> >the NTRANS submodel. Which submodel is the  N minalization factor located
> >in?
> >
> >2) For model inputs I specified the depth increment of 0-15, 15-30, 30-45
> >and 45-80 cm. But, the depth increment for outputs is fixed to 0-5, 5-15,
> >15-30, 30-45, 45-60, 60-90 cm and so on. How is the relationship of the
> >depth increments between model inputs and outputs? Is the user-specified
> >depth increment actually used in simulation?
> >  In sensitivity analysis, a user can change a depth increment for model
> >inputs, but not outputs. Right?
> >
> >Thanks,
> >
> >Hiroshi Hasegawa
> >Agronomist
> >Tohoku National Agricultural Experiment Station
> >Division of Upland Farming
> >  960-2156
> >  Fukushima-shi, Arai, Aza harajuku-minami 50
> >  JAPAN
> >  Phone; 81-24-593-5151
> >  FAX  ; 81-24-593-2155
> >  Email; [log in to unmask]
> >
 
Dr. James Hansen
 
University of Florida
Agricultural and Biological Engineering
PO Box 110570
Gainesville, FL 32611-0570
USA
352-392-7736 (work)
352-392-4092 (FAX)
352-336-9466 (home)
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