proudly sponsored by
|
archiving of SOWACS proudly sponsored by |
|
NOTE: To get off this list, send email to majordomo@aqua.ccwr.ac.za with the body of the message containing the line: unsubscribe sowacs Dear list members. I am working with experimental water retention data to fit parametric equations, which I'd like to use in numerical simulations of water fluxes. I have determined in-situ volumetric soil water content by TDR readings and soil pressure head by tensiometers. However, measured field data disagree with the determined on undisturbed soil cores samples collected at the same site. The problem of hysteresis was partially circumventing collecting the field data in the drying brunch of the hysteretic curve (it was carried out on an instantaneous profile method experiment). The volumes sampled by TDR and the cups of our tensiometers are not the same and, not only the volumes were different but they are separated because of installation procedures. Moreover, the soil samples for the laboratory measurement were collected about 2 meter apart.These factors are probably some explanation for the differences, but our data set is large with many replications and, I believe that some other factors besides soil variability are contributing to that difference ... I have found a limited number of field studies (where in situ measurements were carried out) in which undisturbed soil cores were taken. Someone knows studies concerning the problem of field x laboratory determination of the soil water retention curves ? or have some suggestions ? Any help on this matter will be greatly appreciated Best regards. Wenceslau Teixeira _____________________________________________________________ Wenceslau Geraldes Teixeira Embrapa - AmazŁnia Ocidental - Brasil Universitt Bayreuth Bodenkunde - Abt. Bodenphysik D - 95440 - Bayreuth - Germany Fax: +49 (0)921 552246