Die Bodenkultur - Journal for Land Management, Food and Environment

B. Wimmer, N. Rampazzo, J. Eitzinger, O. Baumgartner, C. Wutzl, H. Schwarz and W. E. H. Blum::

Assessment of soil hydraulic functions for modeling the soil water dynamics of a soybean field


The soil water dynamics of a soybean field in Groß-Enzersdorf Lower Austria was simulated during one vegetation period with the computer "SOIL"-model, using different laboratory and field methods for the determination of the soil hydraulic input data. Hydraulic conductivity functions, as estimated from soil water retention curves, were highly correlated with those measured with an Evaporation Controlled Instantaneous Profile-method in the laboratory; where the GUELPH" permeameter-method for establishing the saturated soil hydraulic conductivity (Ksar) was used.

The data obtained, i.e, bulk density, tension infiltration, saturated conductivity, and simulation results showed clearly that it is almost impossible to establish one unique soil hydraulic conductivity function ofa tilled top soil during a vegetation period, Water infiltration after a heavy thunderstorm following a 4 week dry period could only successfully be simulated using an empirical by bass flow algorithm of the computer model.

Key words:  Soil water balance, hydraulic conductivity; water retention, infiltration.