Ali,
The N-uptake module in DSSAT4 (at least the CROPGRO and CERES-based
models) does include a soil water factor when calculating potential N
uptake by the roots. This function only works when the water and N
balance options are set to "Y" in the experiment file, if the N-balance
option is set to "N", N-uptake is assumed to be non-limiting and this
routine is bypassed. The soil water adjustment factor sets maximum
N-uptake potential when the soil water content for a soil layer = the
drained upper limit and reduces potential uptake for both drier and
wetter conditions. A unique adjustment factor is calculated for each
soil layer in the profile. So while soil texture per se is not a part
of the equation, the adjustment is a function of soil-texture-related
factors (saturated water content, drained upper limit, and lower limit)
that are entered for the soil for each site. I have seen the code that
does this but do not know of a reference that can be cited. Maybe
someone else can help there.
Additionally, water-stress also affects (increases) partitioning of new
growth to the roots. This would be another, albeit indirect, adjustment
to potential N-uptake related to water availability.
Hope this helps,
Stu
Ali Sadeghi wrote:
> I wonder if there is N uptake as a function of soil water content and/or soil texture. Most of the existing watershed models don't have that. I'm not familiar with the crop models?
>
> Any info is appreciated,
>
> Thanks
>
> Ali M. Sadeghi, Soil Physicist
> USDA-ARS, Hydrology & Remote Sensing Lab.
> Rm.102 Blg. 007, BARC-West
> 10300 Baltimore Ave.
> Beltsville, MD 20705
> Phone:(301) 504-6693
> Fax: (301) 504-5048
> Email: [log in to unmask]
>
>
>
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