Influence of root diameter on the penetration of seminal roots into a compacted subsoil - Plant and Soil

A field experiment was conducted to evaluate the influence of root diameter on the ability of roots of eight plant species to penetrate a compacted subsoil below a tilled layer. The soil was a fine sandy loam red-brown earth with a soil strength of about 3.0 MPa (at water content of 0.13 kg kg^-1, corresponding to 0.81 plastic limit) at the base of a tilled layer. Relative root diameter (RRD), which was calculated as the ratio of the mean diameters of roots of plants grown in compacted soil to the mean diameters of those from uncompacted soil, was used to compare the sensitivity of roots to thicken under mechanical stress.

Diameters of root tips of plants grown in soil with a compacted layer were consistently larger than those from uncompacted soil. Tap-rooted species generally had bigger diameters and RRDs than fibrous-rooted species. A higher proportion of thicker roots penetrated the strong layer at the interface than thinner roots. There were differences between plant species in the extent to which root diameter increased in response to the compaction. The roots which had larger RRD also tended to have higher penetration percentage.

The results suggest that the size of a root has a significant influence on its ability to penetrate strong soil layers. It is suggested that this could be related to the effects which root diameter may have on root growth pressure and on the mode of soil deformation during penetration.

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Author notes

1. J. M. Kirby

   Present address: Division of Soils, CSIRO, 2601, Canberra, ACT, Australia

2. A. R. Dexter

   Present address: Silsoe Research Institute, Wrest Park, MK45 4HS, Silsoe, Bedford, UK

Authors and Affiliations

1. Department of Soil Science, The University of Adelaide, Waite Agricultural Research Institute, Glen Osmond, 5064, South Australia

   S. A. Materechera, A. M. Alston, J. M. Kirby & A. R. Dexter

Cite this article

Materechera, S.A., Alston, A.M., Kirby, J.M. et al. Influence of root diameter on the penetration of seminal roots into a compacted subsoil. Plant Soil 144, 297–303 (1992). https://doi.org/10.1007/BF00012888

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• Received: 05 February 1992

• Issue Date: August 1992

• DOI: https://doi.org/10.1007/BF00012888

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