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Do Plant Roots Modify The Soil Water Retention Properties of Rhizospheric Soil ? Evidences from the field and controlled conditions

Abstract : Regulation of water fluxes in soil and plant water uptake are strongly dependent on the hydric properties of the soil. However, these hydric properties might be changed, in turn, by plant roots growing into the soil. Such root-related alteration of soil properties, particularly water retention, can be linked to soil perforation, aggregation of soil particles, release of exudates by roots modifying the soil particles/water properties. This effect could be more pronounced in the rhizosphere, the thin zone around roots influenced by the activity of root and associated microorganisms, and thus differentiating bulk and rhizospheric soil properties. To test if crops and plant root rhizosphere may have a significant effect on water retention, we conducted experiments from laboratory to field scales, covering various time scales. In the field, the alteration of water retention by root systems was tested in different pedological settings for maize and wheat crops. A range of variation in water retention was evidenced, with a consistent increase of 0.01-0.03 g/g of the permanent wilting point in the rhizospheric soil compared to bulk soil. This rhizospheric effect of soil water retention can be related to exopolysaccharides concentration for plant reaching flowering stage. However, this was not the case for younger plant stages, where indicators of the microbial activity appears more linked to water retention variations. Tests conducted with wheat grown in pots in green house controlled condition also shown variations in retention of rhizospheric soil compared to bulk soil (from 0.01 to 0.05 g/g). The amplitude of those variations depended not only on soil type, but also on the wheat varieties with contrasting root development. Even if alteration of soil water retention by roots looks modest in the field, this could mitigate drought impacts or modify the water balance of the root zone. How and how much plants modify the hydric properties, however, deserves further research.
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https://hal.archives-ouvertes.fr/hal-02479429
Contributor : Lauriane Pillet <>
Submitted on : Friday, February 14, 2020 - 2:53:52 PM
Last modification on : Tuesday, March 17, 2020 - 2:07:21 AM

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  • HAL Id : hal-02479429, version 1

Citation

Claude Doussan, Annette Berard, Sonia Czarnes, Laurent Legendre, Jacques Le Gouis, et al.. Do Plant Roots Modify The Soil Water Retention Properties of Rhizospheric Soil ? Evidences from the field and controlled conditions. American Geophysical Union, Fall Meeting 2018, AGU, American Geophysical Union, Etats-Unis, Dec 2014, Washington, United States. ⟨hal-02479429⟩

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