Hello Wendy,
  Information about stresses can be found in:

Ritchie, J.T. 1998. Soil water balance and plant water stress. p.41-54. In G.Y. Tsuji, G. Hoogenboom, and P.K. Thorton (eds.) Understanding options for agricultural production. Kluwer Academic Publishers, Dordrecht, The Netherlands.

and

Godwin, D.C., and U.Singh. 1998. Nitrogen balance and crop response to nitrogen in upland and lowland cropping systems.  p. 55-77. In G.Y. Tsuji, G. Hoogenboom, and P.K. Thorton (eds.) Understanding options for agricultural production. Kluwer Academic Publishers, Dordrecht, The Netherlands.

  Water stress occurs when plant demand is greater than uptake. Water stress-growth affects cell extensibility and water stress-photosynthesis affects carbon accumulation.
  If the excess water- and water-stress occur within a season, that would not be surprising. However, if they both occur on the same day, that would be surprising.
  If it does occur on the same day, you might want to look for something causing low uptake or high demand. It might be possible that a very small root system would not be able to satisfy demand even with excess water in the soil.
  Hope you find what you're looking for.
Sincerely,
Richard


----- Original Message -----
From: Wendy Vance <[log in to unmask]>
Date: Tuesday, August 1, 2006 10:05 pm
Subject: Outputs of water and nitrogen stress
To: [log in to unmask]

> Dear All
>
>
>
> I am using DSSAT for simulation of soybeans and maize across different
> soil types.
>
>
>
> I have been looking at the outputs and would like to know if anyone
> could provide me with further information to explain the following
> outputs from the growth aspects output file;
>
> Water stress - photosynthesis WSPD
>
> Water stress - growth WSGD
>
> Nitrogen stress factor NSTD
>
> Excess water stress EWSD
>
>
>
> One of the reasons why I am asking is that in some cases I have
> outputswhere both water stress and excess water stress are high,
> and others
> where water stress is high and excess water stress is low.  I am
> assuming excess water stress is when there is high soil water
> close to
> saturation, which seems to match my outputs.  However, I am unsure if
> the water stress growth and photosynthesis in these outputs occur
> duringboth wet conditions and drought conditions.
>
>
>
> Any advice will be much appreciated.
>
>
>
> Thanks
>
> Wendy
>
>
>
> [log in to unmask]
>