Hi,

do you have a measurement of the saturated and wilting mositure contents in
your experimental area? maybe, you can use them as estimates to DUL and LL,
or at least to compare the estimates of the regression models.  On my own
opinion, it is better to force the data on DUL and LL using the measured
saturated and wilting point (which varies with soil texture of course if you
check the pF curve) than adjusting the BD you measured in the field just to
achieve a nice fit.

Good references on DUL and LL can be found in:

Ritchie, J.T. 1981a. Water dynamics in the soil-plant-atmosphere. Plants and
Soil. 58: 81-96.

Ritchie, J.T. 1981b. Soil water availability. Plants and Soil. 58: 327-338.

Cheers and goodluck,

Amor V.M. Ines



----- Original Message -----
From: "Tesfalidet Ghebreab" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, December 06, 2002 5:24 PM
Subject: Soil water limits


> Dear listers,
>
> I used regression equations developed by Hutson (1986) and Schulze et
> al (1985) to calaculate drained upper limit (DUL), lower limit (LL) and
> saturated soil water content (SAT). The results from both equations were
> comparable. However, the difference between SAT and DUL was below 5% for
> some of the soil layers and greater than that for others. Is it okay if
> I use them as inputs to the soil water balance module in DSSAT as they
> are? Do I have to modify the measured soil bulk density so that the
> difference between SAT and DUL is equal for all layers?
>
> Thanking you in advance.
>
> Tesfalidet A. Ghebreab
> University of Natal
> School of Environmental Sciences
> PMB, South Africa
>