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Poster De Conférence Année : 2016

Impact of soil management in ditch and related ecosystem services

Résumé

Agriculture must now feed the planet with the lowest environmental impact. Landscape management, including farm ditches management, is a means to protect natural resources from the adverse impacts. Ditch networks have been primarily designed for waterlogging control, erosion prevention and water conveyance. Nonetheless, when properly managed, farmed ditches provide other important ecosystem services, namely groundwater recharge, flood attenuation, water purification, or biodiversity conservation. All ditch ecosystem services depend on many processes, whose occurrence and intensity vary largely with soil characteristics of the ditch beds (Dollinger et al., 2015). The latter often exhibit larger organic carbon contents than their neighbouring field soils (Vaughan et al., 2008) and larger adsorption properties (e.g., Cooper et al., 2004; Margoum et al., 2006). They therefore favor contaminant retention, e.g. pesticides (Dollinger et al., submitted). Moreover, they exhibit specific porosities and infiltration properties because of successive and frequent sediment deposits due to surface flow and re-enforced by vegetation patches within ditches (Devi and Kumar, 2015). In turn, these specific ditch bed soils support hydrophytic vegetation with specific rooting patterns (Vaughan et al., 2008). When vegetated, the macroporous structure created by channel roots and warm galleries enhances the infiltration capacities of ditch beds and in turn contribute to the limitation of pesticides loads to surface water bodies but may also increase the risk of groundwater contamination (Dagès et al., 2015). By managing the surface characteristics of the soils in the ditches, namely by dredging, chemical weeding, mowing and burning, water related ecosystem services, may be promoted or limited (Dollinger et al., 2015). This study aimed to quantify the impact of the management of soils in ditches on the buffering effect of dicthes on surface and subsurface water contamination by pesticides . We first investigated ditch soil sorption properties, subsurface transport mechanisms and hydraulic transfer. We then classified ditch bed soils from their surface characteristics according to their hydraulic, infiltration and retention capacities for three pesticides groups (hydrophilic, slightly hydrophobic, highly hydrophobic). A large range of scenarios of hydrological and contamination contexts for each type were built and simulated with semi-quantitative and biophysical models. Finally, the meta-analysis of the simulations allows to rank the ditches and ditches soils against surface and groundwater contamination from observable characteristics.
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Dates et versions

hal-01381028 , version 1 (13-10-2016)

Identifiants

  • HAL Id : hal-01381028 , version 1

Citer

Cécile Dagès, Jean-Stéphane Bailly, Jeanne Dollinger, Lanoix Marthe, David Crevoisier, et al.. Impact of soil management in ditch and related ecosystem services. AUSTIN INTERNATIONAL CONFERENCE ON SOIL MODELING, Mar 2016, Austin, United States. . ⟨hal-01381028⟩
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