ABSTRACT
Roots anchor a plant, explore the soil for mineral nutrients and water and are the site of production of several growth controlling substances. To carry out these requirements root systems grow by branching as well as by longitudinal and radial expansion. During their life roots add to the organic and inorganic materials in the surrounding soil. Some activities such as the compression and shearing of soil during root expansion are likely to reduce the stability of natural soil aggregates whereas the addition of organic matter may improve aggregate strength. The significance of different root activities is discussed in relation to the improvement of soil structural conditions. Some methods are presented for the assessment in situ of the influence of roots on soil structure. Rooting characteristics likely to encourage the improvement of a damaged structure are identified.
