EGU23-6447, updated on 22 Feb 2023
EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Alteration of soil biophysical properties after decomposition of contrasting root systems

David Boldrin1, Kenneth W. Loades1, Jonathan A. Knappett2, Anthony K. Leung3, and Glyn A. Bengough2
David Boldrin et al.
  • 1The James Hutton Institute, Invergowrie, Dundee DD2 5DA, UK
  • 2School of Science and Engineering, University of Dundee. Dundee, DD2 5DA, UK
  • 3Department of Civil and Environmental Engineering, School of Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China

Background: Increased water infiltration in the presence of vegetation has been reported in the literature for both woody and herbaceous plants. However, there is a lack of experimental data on macropores development after root decomposition, and consequent alteration of soil biophysical properties.

Methods: To test the effect of contrasting root systems on saturated hydraulic conductivity [Ks], individual plants of Daucus carota [F-DC] (Forb; coarse taproot with few small lateral roots); Deschampsia cespitosa [G-DC] (Grass; fibrous root system), Lotus corniculatus [L-LC] (Legume; thin taproot with several lateral roots) were grown in columns (50 mm diameter; 315 mm height) with sandy loam soil packed at 1.4 Mg/m3. Following 7-month plant-establishment, the columns were split into five sections (60 mm height each). Ks was tested in each section (i.e., down soil depth) using a constant-head permeameter. Fallow soil was also tested as control. Following the Ks tests, column sections (i.e., soil cores) were buried in soil and left for decomposition in a controlled environment. After 7-month decomposition, sections were excavated and re-tested for Ks. To measure the biophysical properties of soil in the root-channels, the same three species were also grown in the top-half of a soil column (300 mm height; 50 mm width; 1.2 Mg/m3) longitudinally divided by a 40-μm nylon-mesh. The columns were maintained at a 15-degree slope to facilitate root growth at the soil-mesh interface. Following plant establishment (5 months), plants were killed by herbicide. The soil columns (rooted and control fallow) were buried in soil and left for decomposition in a controlled environment for 7 months. After the decomposition period, the soil columns were split, and the mesh was removed to expose the developed root-channels. The soil in the exposed root-channels was tested for water sorptivity, water repellency, water retention, soil stability in water, hardness and elasticity.

Results: Ks after plant establishment did not differ notably from that of control soil. In contrast, an abrupt increase in Ks (up to 80-times in F-DC) was measured after decomposition in the vegetated soils (e.g., from 2.04e-6 ± 9.20e-7 to 1.48e-4 ± 3.30e-5 in F-DC at 3 – 63 mm depth). The increase in Ks in G-DC and L-LC was smaller (up to 20-times) compared to F-DC. No Ks change was observed in the control soil. Soil surrounding the root-channels showed greater stability and plant available water. However, we observed smaller sorptivity and greater water repellency in soil surrounding the root-channels of F-DC and G-DC, respectively.

Conclusions: Biophysical alteration of soil after root decomposition depends on plant species. Our findings show that it is possible to engineer soil biophysical properties and bio-pores using contrasting herbaceous species.


How to cite: Boldrin, D., Loades, K. W., Knappett, J. A., Leung, A. K., and Bengough, G. A.: Alteration of soil biophysical properties after decomposition of contrasting root systems, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-6447,, 2023.