Ein Meß‐ und Auswerteverfahren zur Bestimmung der ungesättigten Wasserleitfähigkeit an Böden in situ

Remarks on the determination of the unsaturated hydraulic conductivity based on field measurements In a previous paper hydraulic conductivity — moisture tension functions have been evaluated by a field method for various layers of a fallow loess soil (grey brown podzolic soil). The aim of the paper presented here, is to demonstrate the magnitude of error when the hydraulic functions are calculated in the presence of transpiring plants, as it was done elsewhere. The error arises, because the water uptake rates of roots are added to the capillary water flux through the soil matrix. From the present investigation it becomes clear that with advancing growing stages of winter wheat and the increasing water extraction ability the error becomes more and more pronounced. The conductivity values may then be overestimated by a factor of half the power of ten as compared to the results computed from the fallow soil.

Section: Theorieunclassified

Zur Bestimmung der ungesättigten Wasserleitfähigkeit im Felde

Ehlers

1976

Influence of water content and soil properties on unsaturated hydraulic conductivity of some red and black soils

Bhatnagar

Nagarajarao

Gupta

1979

The unsaturated hydraulic conductivity was determined in the laboratory for some red and black soils, following water movement into a horizontal column of homogenous soil of uniform packing. A highly significant positive relationship was found between moisture content and hydraulic conductivity values in all the soils studied. Correlation coefficients calculated for the relationships between soil constituents/properties and the change in hydraulic conductivity per unit change in moisture content (regression coefficient between hydraulic conductivity and moisture content) have shown positive relationship to sand and negative relationships to silt, silt + clay, clay, carbonates, aggregates > 0.25 mm and saturated hydraulic conductivity. It is concluded that the unsaturated hydraulic conductivity decreases rapidly with decrease in moisture content and this decrease depends on the soil constituents/properties and differences between soil types are clear. The amount of water stored in a soil profile and the rate of its transmission are of great interest to the Soil Scientists and Agronomists. Water is transmitted through soil both under saturated and unsaturated conditions. Unsaturated flow processes are, in general, complicated and difficult to describe quantitatively. Nevertheless, Beliehungen mischen WasserleltfiihigLeit und

EDV‐gestütztes Meß‐ und Auswerteverfahren zur Bestimmung der ungesättigten Wasserleitfähigkeit nach der Verdunstungsmethode

Krahmer

1987

In der Literatur wird eine Vielzahl von Methoden zur Bestimmung der ungesättigten Wasserleitfähigkeit des Bodens in Abhängigkeit vom Wassergehalt bzw. von der Saugspannung aufgezeigt. Ein häufiger Nachteil ist dabei der große Zeitaufwand für die Messung und/oder Auswertung. Die hier vorgestellte Gerätekombination zur Anwendung der Verdunstungsmethode und die entsprechende Software erlauben eine rationellere Parameterbestimmung der ungesättigten Wasserleitfähigkeit und eine Darstellung in analytischer Form.