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Le Bayon, Renée-Claire

Nom
Le Bayon, Renée-Claire
Affiliation principale
Email
claire.lebayon@unine.ch
Identifiants
https://libra.unine.ch/handle/123456789/319
_
0000-0002-1237-497X

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  • Publication
    Accès libre
    Lumbricid macrofauna alter atrazine mineralization and sorption in a silt loam soil
    (2006)
    Binet, Françoise
    ;
    Anne Kersanté
    ;
    Munier-Lamy, Colette
    ;
    Le Bayon, Renée-Claire 
    ;
    Belgy, Marie-José
    ;
    Shipitalo, Martin J.
    Atrazine is a widely used herbicide and is often a contaminant in terrestrial and freshwater ecosystems. It is uncertain, however, how the activity of soil macrofauna affects atrazine fate and transport. Therefore, we investigated whether earthworms enhance atrazine biodegradation by stimulating herbicide degrading soil microflora, or if they increase atrazine persistence by facilitating herbicide sorption. Short (43 d) and medium term (86 d) effects of the earthworms Lumbricus terrestris and Aporrectodea caliginosa on mineralization, distribution, and sorption of U-ring-14C atrazine and on soil C mineralization was quantified in packed-soil microcosms using silt loam soil. A priming effect (stimulation of soil C mineralization) caused by atrazine supply was shown that likely lowered the earthworm net effect on soil C mineralization in atrazine-treated soil microcosms. Although earthworms significantly increased soil microbial activity, they reduced atrazine mineralization to 14CO2–C from15.2 to 11.7% at 86 d. Earthworms facilitated formation of non-extractable atrazine residues within C-rich soil microsites that they created by burrowing and ingesting soil and organic matter. Atrazine sorption was highest in their gut contents and higher in casts than in burrow linings. Also, gut contents exhibited the highest formation of bound atrazine residues (non-extractable atrazine). Earthworms also promoted a deeper and patchier distribution of atrazine in the soil. This contributed to greater leaching losses of atrazine in microcosms amended with earthworms (3%) than in earthworm-free microcosms (0.003%), although these differences were not significant due to high variability in transport from earthworm-amended microcosms. Our results indicated that earthworms, mainly by casting activity, facilitated atrazine sorption, which increased atrazine persistence. As a consequence, this effect overrode any increase in atrazine biodegradation due to stimulation of microbial activity by earthworms. It is concluded that the affect of earthworms of atrazine mineralization is time-dependent, mineralization being slightly enhanced in the short term and subsequently reduced in the medium term.
  • Publication
    Accès libre
    Annual variations in earthworm surface-casting activity and soil transport by water runoff under a temperate maize agroecosytem
    (Elsevier, 2002)
    Le Bayon, Renée-Claire 
    ;
    Corrie Moreau
    ;
    Chantal Gascuel-odoux
    ;
    Binet, Françoise
    Investigations were conducted on both the annual patterns of earthworm casting activity and the annual variations in soil and phosphorus (P) transfers by water runoff, under a temperate maize crop, to determine whether there is any time synchronism over the year between these processes that could increase risk of soil erosion. Cast dynamics were measured at 15-day intervals for 1 year. Phosphorus forms were determined in runoff waters and the sediments collected were analyzed for nitrogen (N), carbon (C) and P contents. As long as there was no crust at the soil surface, no runoff was observed. Once the sealing crust formed, the soil erosion began. After the rainstorm events in August, soil erosion already reached 70% of the total soil loss that occurred over the crop year. A total of 140 g m−2 year−1 of sediment was lost by the end of the year. A time synchronization was observed between tillage practices and highest cast productions over the year, which were then interrupted for up to 5 weeks after both ploughing and crop harvest. In particular, the absence of anecic casts onto the soil till September underline that Lumbricus terrestris was most affected by ploughing. The likelihood that earthworm casts contributed to soil erosion was enforced by the correlation between the timing of cast disappearance and the increase in sediment transfers for rainstorm events observed in summer, as well as for long rainy period in fall/winter. However, we could not outline a systematic correlation over the year but just for defined periods. Particulate soil erosion and P amounts in runoff waters decreased (55–2 g m−2, and 19–5 mg of P losses m−2, respectively) through the crop year. However, the content of organic matter in sediment increased (2.54–5.16%) compared to the initial soil (1.8%), as well as the P concentration (1.1–1.6 mg g−1).
  • Publication
    Accès libre
    Earthworm surface casts affect soil erosion by runoff water and phosphorus transfer in a temperate maize crop
    (2001)
    Le Bayon, Renée-Claire 
    ;
    Binet, Françoise
    To test the hypothesis that earthworm surface casts contribute to soil erosion and nutrient transfers in a temperate maize crop, two rainfall experiments were set up. One was focused on the erodibility of earthworm casts, the second examined in how casts affect water runoff and nutrient transfers. Casts produced from anecic and endogeic earthworm species were both analyzed. Visual observations in the field showed no cast transport but only cast disintegration and transfers of particles. Erodibility of newly deposited casts was high and differed significantly between age groups. Cast erosion was significantly positively related to initial mass when young but not when old. The paradox is that despite a high cast abundance (25% of the area) and obvious cast erosion, amounts of sediment and nutrient losses (C, N and P) in the runoff were at least twice as high without, than in the presence of, surface casts. Earthworm activities were shown to act as a physical brake for soil erosion by (i) creating a surface roughness with the deposition of surface casts and (ii) reducing water runoff by associated enhanced water percolation. Once the breaking-down point of the physical resistance of casts was reached, all surface casts were quickly disintegrated and finally completely washed away. The amount of particulate phosphorus recovered in water runoff was 34.7 mg P m−2, while 128.5 mg P m−2 was estimated to have been released from casts. The transfers were found to occur over a short-distance through successive deposition/suspension of soil particles in the water runoff.
  • Publication
    Accès libre
    Space-time dynamics in situ of earthworm casts under temperate cultivated soils
    (1999)
    Binet, Françoise
    ;
    Le Bayon, Renée-Claire 
    Soil does not always benefit from disturbance by earthworms. We investigated whether (under a temperate climate and in maize growing in rows running down-hill) earthworm casts could contribute to soil erosion and losses of nutrients in runoff water. Observations of casts were made in compacted (wheel-tracks) and non-compacted (untrafficked) inter-rows, for a 2-month period in spring. Estimates of surface-cast production in a temperate maize crop ranged between 2.5 to 3.2 kg (d.w soil) m−2 y−1. The mean life-time of casts was shown to vary from 4 d during wet periods to 14 d during dry periods. The oldest casts recovered in situ were at least 2-months old. The relative loss of casts was 70% and 20% during the wet and dry periods, respectively. Splash and runoff effects of rainfall were the main causes of deterioration of surface-casts, especially fresh ones. Apart from rainfall events, a prolonged process of erosion took place whereby casts disappeared gradually by collapsing and mixing in the matrix bulk-soil. Cast production was found to be 50% higher in compacted soil. Particularly, an increase by 20% of soil compactness led to a 2-fold increase of casting activity per worm. This suggests that risks of soil erosion could be increased by earthworm surface-casting in compacted soil. Spatial distributions of both casts and earthworms across inter-rows were shown to be similar under non-compacted inter-rows but different in compacted areas. We estimated that annual soil erosion from surface-casts would range from between 1.2 to 1.5 kg (d.w) m−2 y−1.