Preferential transport of water through soil macropores is a governing process in the facilitated transport of strongly sorbing compounds. The aim of this study was to investigate the relationships between macropore density and the hydraulic conductivity of the soil and to test the sampling representativeness of soil columns for the measurement of saturated hydraulic conductivity. Macropore density was determined in three horizons in four typical Danish soil types (third year of pasture), and saturated hydraulic conductivity and near-saturated hydraulic conductivity were measured in the laboratory on undisturbed soil columns (6,280 cm3) in the same three horizons. A strong relationship between macropore density and the mean particle diameter was found in the B and C horizons. A poor relationship was found between macropore density and the hydraulic conductivity at a matric potential of −10 hPa, whereas a stronger relationship was found at saturation. Results of the test of the number of soil columns needed for a representative distribution of macropores for the measurement of saturated hydraulic conductivity indicated that approximately six soil columns were enough. Our work suggests that integrating knowledge of the abundance of macropores in relation to soil type and land use will increase the performance of pedotransfer functions in predicting saturated hydraulic conductivity.
1Department of Agroecology, Aarhus University, Tjele, Denmark.
2Department of Biotechnology, Aalborg University, Aalborg, Denmark.
Address for correspondence: Bo Vangso Iversen, PhD, Aarhus University,Blichers Allé 20, P.O. Box 50, DK-8830 Tjele, Denmark. E-mail: firstname.lastname@example.org
Financial Disclosures/Conflicts of Interest: This work was financed by the Ministry of Food, Agriculture and Fisheries of Denmark under the research program “Animal Husbandry, the Neighbours and the Environment.”
Received March 20, 2012.
Accepted for publication July 11, 2012.