THE EFFECTS OF ROOTS AND ORGANIC MATTER ON THE STRUCTURE AND
HYDRAULIC PROPERTIES OF AGRICULTURAL SOILS
Richard Whalley and Peter Matthews
Rothamsted Research, Harpenden, West Common, Hertfordshire, United Kingdom, AL5 2JQ
E-mail: Richard.Whalley@bbsrc.ac.uk
The effect of root activity on the structure and hydraulic properties of soil at the root-soil
interface will be considered. Data from laboratory experiments provides evidence that soil
structure at the root-soil interface is different to that in the bulk soil. Evidence from both thin
section analysis and the measurement of the water release characteristic will be presented.
These data sets both show that root activity can increase the proportion of larger pores in the
rhizosphere. We consider what effect this might have for root functioning.
We describe an experiment to test the hypotheses that water repellence is in part responsible
for changes to soil hydraulic function at the root soil interface. We were unable to support this
hypothesis; however, data will be presented to show that changes in organic matter content
can affect water repellence. With the use of this data and similar data sets in the literature we
present a general result to explain how soil management can affect the water repellence of
soil as function of soil type.
1. Whalley, W.R., Riseley, B., Leeds-Harrison, P.B., Bird, N.R.A., Leech P.K. and Adderley,
W.P. (2005) Structural differences between bulk and rhizosphere soil. European Journal
of Soil Science. 56: 353-360.
2. Whalley, W.R., Leeds-Harrison, P.B., Leech, P.K., Riseley, B.A. and Bird, N.R.A. (2004)
The hydraulic properties of the soil at root-soil interface. Soil Science. 169: 90-99.