Calculation of Hydraulic Conductivities of Soils from Texture and Organic matter Content

Abstract

It is demonstrated how the values of the three constants in a convenient formula for the calculation capillary conductivities can be evaluated from texture and organic matter content of a soil. In this way it is possible to calculate the conductivity function of any soil provided that an adequate analysis of granular composition and humus content analysis is available. Particularly for practical purposes the quick availability of the results of this calculation is of great advantage over time consuming direct measurement or calculation with constants evaluated from moisture retention curves. To increase the practical significance of the method the effect of pore size hysteresis on the calculated conductivity functions is accounted for in a pragmatical way. Conductivity functions for a number of single‐layered soil types in the Netherlands are given. In a subsequent paper it will be shown how the discussed method is put into practice in a computation of capillary rise from the groundwater table in multi‐layered soil profiles.

Evaluation of different representations of the particle-size distribution to predict soil water retention

“…Correlations between contents of textural components are often observed in regional databases (e.g., Nielsen and Shaw, 1958) and thus a small number of parameters may be sufficient to characterize the texture for PTF development. To characterize PSD, the median diameter was found useful first in sandy media (Bedinger, 1961), and then in soils with a wide range of textures (Bloemen, 1980;Campbell, 1985). Campbell (1985), Scheinost et al (1997) and Minasny et al (1999) used the geometric mean diameter along with its standard deviation to estimate soil water retention.…”

Short-term effects of crop rotation, residue management, and soil water on carbon mineralization in a tropical cropping system

“…From this study, θ FC =0.29 cm 3 cm −3 and, according to Bloemen (1980), the average minimum volumetric soil water content for most soils is 6%. Hence, we set θ d =0.06 cm 3 cm −3 .…”

Constructing a saturated hydraulic conductivity map of Spain using pedotransfer functions and spatial prediction

“…Soil hydraulic properties have been the most often predicted and they can be classified in different ways (McBratney et al, 2002). Two types of PTFs are the most common (Reynolds et al, 2000): the first one is called the class PTF and estimates the hydrological behaviour of each soil textural class (Bloemen, 1980;Tietje and Hennings, 1996), and the second one is the continuous PTF that estimates a unique regression equation for all textures. In this last function, at least one of the statistical independent variables used in the regression equation should be the percentage of sand, clay or silt.…”