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Mechanical impedance to root growth: a review of experimental techniques and root growth responses
Author(s) -
BENGOUGH A. G.,
MULLINS C. E.
Publication year - 1990
Publication title -
journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 0022-4588
DOI - 10.1111/j.1365-2389.1990.tb00070.x
Subject(s) - penetrometer , elongation , mechanical impedance , penetration (warfare) , root (linguistics) , electrical impedance , geotechnical engineering , resistance (ecology) , materials science , soil science , soil water , geology , engineering , composite material , agronomy , biology , linguistics , philosophy , operations research , electrical engineering , ultimate tensile strength
SUMMARY Mechanical impedance to root growth is one of the most important factors determining root elongation and proliferation within a soil profile. Penetrometers overestimate resistance to root growth in soil by a factor of between two and eight and, although they remain the most convenient method for predicting root resistance, careful interpretation of results and choice of penetrometer design are essential if improved estimates of soil resistance to root elongation are to be obtained. Resistance to root growth through pressurized cells containing ballotini considerably exceeds the confining pressure applied externally to these cells. Results from this work are reappraised. Existing models of soil penetration by roots and penetrometers are reviewed together with the factors influencing penetration resistance. The interpretation of results from mechanical impedance experiments is examined in some detail and root responses, including possible mechanisms of response, are discussed.