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See detailÉVOLUTION DE LA TENEUR EN EAU LE LONG D’UNE TOPOSEQUENCE FORESTIERE ARGILO-LIMONEUSE
Deraedt, Deborah ULg; Colinet, Gilles ULg; Degré, Aurore ULg

in Milieux Poreux et Transferts Hydriques (in press)

For the hydrological modeling of forested watersheds, the understanding of the forest hydrodynamic is essential. This study focusses on the hydrology of a Belgian forested plot with high stoniness and ... [more ▼]

For the hydrological modeling of forested watersheds, the understanding of the forest hydrodynamic is essential. This study focusses on the hydrology of a Belgian forested plot with high stoniness and steep slope. The soil water content is monitored at several positions on the toposequence and at different depth. During rain events, peak in soil water content are observed in different depth depending on the position along the toposequence. [less ▲]

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See detailCan DEM time series produced by UAV be used to quantify diffuse erosion in an agricultural watershed?
Pineux, Nathalie ULg; Lisein, Jonathan ULg; Swerts, Gilles ULg et al

in Geomorphology (2017), 280

Erosion and deposition modelling should rely on field data. Currently these data are seldom available at large spatial scales and/or at high spatial resolution. In addition, conventional erosion ... [more ▼]

Erosion and deposition modelling should rely on field data. Currently these data are seldom available at large spatial scales and/or at high spatial resolution. In addition, conventional erosion monitoring approaches are labour intensive and costly. This calls for the development of new approaches for field erosion data acquisition. As a result of rapid technological developments and low cost, unmanned aerial vehicles (UAV) have recently become an attractive means of generating high resolution digital elevation models (DEMs). The use of UAV to observe and quantify gully erosion is now widely established. However, in some agro-pedological contexts, soil erosion results from multiple processes, including sheet and rill erosion, tillage erosion and erosion due to harvest of root crops. These diffuse erosion processes often represent a particular challenge because of the limited elevation changes they induce. In this study,we propose to assess the reliability and development perspectives of UAV to locate and quantify erosion and deposition in a context of an agricultural watershed with silt loam soils and a smooth relief. Erosion and deposition rates derived from high resolution DEM time series are compared to field measurements. The UAV technique demonstrates a high level of flexibility and can be used, for instance, after a major erosive event. It delivers a very high resolution DEM(pixel size: 6 cm) which allows us to compute high resolution runoff pathways. This could enable us to precisely locate runoff management practices such as fascines. Furthermore, the DEMs can be used diachronically to extract elevation differences before and after a strongly erosive rainfall and be validated by field measurements. While the analysis for this study was carried out over 2 years, we observed a tendency along the slope from erosion to deposition. Erosion and deposition patterns detected at the watershed scale are also promising. Nevertheless, further development in the processing workflow of UAV data is required in order to make this technique accurate and robust enough for detecting sediment movements in an agricultural watershed affected by diffuse erosion. This area of investigation holdsmuch potential as the images processing is relatively new and expanding. [less ▲]

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See detailPrésentation des activités du PCNSW
Legrain, Xavier ULg; Michel, Brieuc ULg; Roda, Mathilde ULg et al

Conference (2016, December 14)

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See detailTrace metals in soil and plant : from natural to contaminated ecosystems
Colinet, Gilles ULg

Scientific conference (2016, December)

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See detailSite expérimental du Martinet - Premiers résultats
Liénard, Amandine ULg; Colinet, Gilles ULg

Conference given outside the academic context (2016)

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See detailAssessment of vertical contamination of Cd, Pb and Zn in soils around a former ore smelter in Wallonia, Belgium
Liénard, Amandine ULg; Colinet, Gilles ULg

Conference (2016, September 14)

Examples of sites contaminated by atmospheric fallouts are numerous across former industrial areas, among which the valleys of Sambre and Meuse in Wallonia hosted metal ore treatment factories. We have ... [more ▼]

Examples of sites contaminated by atmospheric fallouts are numerous across former industrial areas, among which the valleys of Sambre and Meuse in Wallonia hosted metal ore treatment factories. We have studied the fate of Cd, Pb and Zn in soils affected by atmospheric deposition in the vicinity of old smelters. The importance of vertical redistribution of contaminants in soils is questioned and the aims of this paper are to i) characterize the vertical distribution of TEs and soil properties along diverse soil profiles, ii) evaluate enrichment or impoverishment of TEs along the profiles to discriminate anthropogenic or geogenic origin of contaminations and iii) evaluate whether soil type or land use influenced the mobility of contaminants in the selected profiles. Concentrations of trace elements (Cd, Co, Cr, Cu, Ni, Pb, and Zn) and major elements (Ca, Mg, K, Fe, Al, and Mn) as well as pHKCl and TOC were measured on 22 profiles located in a 3 km radius of a former ore treatment plant in Wallonia (Belgium). Enrichment factor (EF), vertical impoverishment factor (VIF), and availability ratio (AR) were used as diagnostic tools of contamination and migration of Cd, Pb, and Zn in profiles. Data revealed that soil profiles are significantly contaminated. The ranges of enrichment factors for Cd (17-3570), Pb (1-2883), and Zn (2-309) are very broad with the higher EF in the topsoil of profile. VIFs of subhorizons are rarely above 1. In a few remaining cases with VIF > 1, the main factor explaining is soil type (especially, Colluvic Regosols, Luvisols, and, Cambisols with shale load). Cd, Pb and Zn ARs are strongly correlated with TOC and to a lesser extent with pHKCl. Pb and Zn ARs are influenced by soil type and land use only plays on Zn AR. The Cd availability is independent by these two factors. The contents of trace elements measured in soil profiles are very high especially in topsoil. Until now, the Cd, Pb, and Zn vertical distribution shows a low migration from topsoil up to depth. However, we must not minimize the hazard of a future potential transfer. [less ▲]

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See detailInvestigating the effect of plant-derived amendments on PAHs degradation in brownfield contaminated soils
Davin, Marie ULg; Starren, Amandine ULg; Colinet, Gilles ULg et al

Conference (2016, September 13)

Polycyclic aromatic hydrocarbons (PAHs) are a class of persistant organic compounds of major concern that tend to accumulate in the environment, damaging ecosystems and health. Brownfields represent an ... [more ▼]

Polycyclic aromatic hydrocarbons (PAHs) are a class of persistant organic compounds of major concern that tend to accumulate in the environment, damaging ecosystems and health. Brownfields represent an important tank for PAHs that require remediation. As an alternative to environmentally aggressive, expensive and often disruptive soil remediation strategies, experiences have been carried on to understand and develop techniques based on bioremediation and phytoremediation. PAHs degradation experiments were conducted in microcosms (laboratory scale) in order to determine whether several plant-derived amendments could enhance bioremediation. Briefly, samples of aged contaminated soils were treated with different concentrations of Medicago sativa or Trifolium pratense root exudates or dried roots, commercial saponin, a natural surfactant found in some plant roots such as some Fabaceae, and some samples were left unamended as controls. Soil samples were incubated for two and four weeks at controlled temperature (28°C). Carbon dioxide emission was monitored throughout the whole incubation. At the end of each experiment, dehydrogenase activity was measured as an indicator of microbiological activity and residual PAHs were determined using High-Performance Liquid Chromatography with Fluorimetric Detection (HPLC-FLD). In total, eleven amendment modalities and two incubation periods were tested and repeated four times. Preliminary experiments show promising results as amended samples seem to show different respiration activities. Ongoing studies will allow discussion as to whether or not PAHs degradation is influenced by the different modalities and if there are any differences according to the nature and concentration of the amendment. [less ▲]

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See detailLa gestion de la matière organique du sol, un enjeu important pour limiter la lixiviation du nitrate vers les eaux souterraines
Vandenberghe, Christophe ULg; Colinet, Gilles ULg

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment (2016), 21

Description of the subject. The nitrate concentration in half of the groundwater bodies of the Walloon Region (Belgium) has justified their classification as vulnerable zones under the Nitrates Directive ... [more ▼]

Description of the subject. The nitrate concentration in half of the groundwater bodies of the Walloon Region (Belgium) has justified their classification as vulnerable zones under the Nitrates Directive (ND). This vulnerable area has a relatively high diversity of agro-soil environments. Thus, the nitrogen content of agricultural soils can vary locally by a factor 4. Objectives. This study aimed to establish whether the carbon content of a soil is a significant risk factor in nitrate leaching to groundwater. Method. The article is based on measurements of nitrate nitrogen residue (APL) and soil total organic carbon (TOC) at the beginning of the leaching period. The measurements were made in 2012 in 1,500 plots, during inspections organized by the Wallonia Public Service. This was as part of the application of the Program for the Sustainable Management of Nitrogen in Agriculture, the scheme for implementing the ND within the Walloon region. Results. Examination of the results showed both that the APL was positively correlated to the TOC and that plots with “noncompliant” APL results had a significantly higher average TOC than the other plots. Conclusions. Since APL is an environmental indicator of the risk of nitrate leaching, it appears that the TOC may constitute a risk of groundwater contamination by nitrate. It is therefore advisable to improve the inclusion of this parameter in advice regarding nitrogen fertilization and secondly, in the case of summer harvest, to better manage the sowing of catch crops. [less ▲]

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See detailInvestigating the Effect of Plant Root Exudates and of Saponin on Polycyclic Aromatic Hydrocarbons Solubilization in Brownfield Contaminated Soils
Davin, Marie ULg; Fauconnier, Marie-Laure ULg; Colinet, Gilles ULg

Conference (2016, August 08)

In Wallonia, there are 6,000 estimated brownfields (rising to over 3.5 million in Europe) that require remediation. Polycyclic Aromatic Hydrocarbons (PAHs) are a class of recalcitrant carcinogenic ... [more ▼]

In Wallonia, there are 6,000 estimated brownfields (rising to over 3.5 million in Europe) that require remediation. Polycyclic Aromatic Hydrocarbons (PAHs) are a class of recalcitrant carcinogenic/mutagenic organic compounds of major concern as they accumulate in the environment and represent 17% of all encountered pollutants. As an alternative to environmentally aggressive, expensive and often disruptive soil remediation strategies, a lot of research has been directed to developing techniques targeting organic pollutants. The following experiment, based on the observation that PAHs soil content decreases in the presence of plants, aimed at improving our understanding of the underlying mechanisms involved in phytoremediation. It focusses on plant root exudates and whether they improve PAHs solubilization, which would make them more available for bioremediation by soil microorganisms. The effect of saponin, a natural surfactant found in some plant roots such as members of the Fabaceae family, on PAHs solubilization was also investigated as part of the implementation of the experimental protocol. The experiments were conducted on soil collected from a brownfield in Saint-Ghislain (Belgium) and presenting weathered PAHs contamination. Samples of soil were extracted with different solutions containing either plant root exudates or commercial saponin. Extracted PAHs were determined in the different aqueous solutions using High-Performance Liquid Chromatography and Fluorimetric Detection (HPLC-FLD). Both root exudates of alfalfa (Medicago sativa L.) or red clover (Trifoliumpratense L.) and commercial saponin were tested in different concentrations. Distilled water was used as a control. First of all, results show that PAHs are more extracted using saponin solutions than distilled water and that the amounts generally rise with the saponin concentration. However, the amount of each extracted compound diminishes as its molecular weight rises. Also, it appears that passed a certain surfactant concentration, PAHs are less extracted. This suggests that saponin might be investigated as a washing agent in polluted soil remediation techniques, either for ex situ or in situ treatments, as an alternative to synthetic surfactants. On the other hand, preliminary results on experiments using plant root exudates also show differences in PAHs solubilization compared to the control solution. Further results will allow discussion as to whether or not there are differences according to the exudates provenance and concentrations. [less ▲]

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See detailCrop residue management in arable cropping systems under temperate climate. Part 1: Soil biological and chemical (phosphorus and nitrogen) properties. A review
Lemtiri, Aboulkacem ULg; Degrune, Florine ULg; Barbieux, Sophie ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment (2016)

Interacting soil organisms support biological processes that participate in soil functions, organic matter decomposition, and nutrient cycling. Earthworms and microorganisms play a range of beneficial ... [more ▼]

Interacting soil organisms support biological processes that participate in soil functions, organic matter decomposition, and nutrient cycling. Earthworms and microorganisms play a range of beneficial roles in agricultural systems, including increased organic matter mineralization, nutrient cycling, and soil structure stabilization. The following aspects of crop residue management effects are examined in this paper: (i) earthworm composition and structure; (ii) soil microbial communities; and (iii) phosphorus (P) and nitrogen (N) element availability and distribution in the soil profile. Conventional tillage (ploughing) is often reported to generate decreased soil organism abundance and diversity, primarily earthworms and microorganisms, as well as a uniform distribution of the nutrients P and N within the ploughed soil horizon. Soil residue incorporation of mineral particles can maintain P and N levels, however returning soil also increases aeration and the activation of microbial activity. Hence, comparisons of tillage effects on soil biological functioning and nutrient cycling remain unclear. This review highlights the challenges in establishing definitive evidence regarding the effects of crop residue management on soil organisms and nutrient dynamics. The studies examined reported variability in soil and climate, and the complexity of soil processes contributed to the absence of clear findings. Further research is required under temperate climate conditions. [less ▲]

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See detailNo favorable effect of reduced tillage on microbial community diversity in a silty loam soil (Belgium)
Degrune, Florine ULg; Theodorakopoulos, Nicolas ULg; Dufrêne, Marc ULg et al

in Agriculture, Ecosystems & Environment (2016), 224

Among the soil management practices used to promote sustainable agriculture, reduced tillage and retention of residues from the previous crop are reported to enhance significantly both soil fertility and ... [more ▼]

Among the soil management practices used to promote sustainable agriculture, reduced tillage and retention of residues from the previous crop are reported to enhance significantly both soil fertility and crop productivity. Here, high-throughput sequencing (454 technology) was used to see how the tillage regime (conventional vs. reduced tillage) and the fate of crop residues (retention or removal) affect microbial communities at two sampling depths (top soil: 0–5 cm and deeper soil: 15–20 cm) in a fertile silty loam soil in Belgium. All combinations of these three factors were studied. After 6 years of conversion from conventional to reduced tillage, depth emerged as the main factor responsible for variation in microbial diversity, tillage regime ranked second, and finally, crop residue fate had no influence on microbial diversity. For both bacteria and fungi, the diversity appeared higher in the top soil than in the deeper soil, and surprisingly, higher under conventional than under reduced tillage. These differences are explained by changes in community composition due to taxon loss rather than taxon replacement. The specific local set of environmental conditions (a loess-derived soil and an oceanic temperate climate) may explain these results. These observations raise the question: does impoverishment in indicator taxa influence soil processes, and thus crop production? To answer this question, we discuss how the presence of certain indicator taxa liable to play an ecological role might relate to crop productivity. [less ▲]

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See detailEvaluation and monitoring of soil quality
Colinet, Gilles ULg

Scientific conference (2016)

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See detailCrop residue management in arable cropping systems under a temperate climate. Part 2: Soil physical properties and crop production. A review
Hiel, Marie-Pierre ULg; Chelin, Marie ULg; Parvin, Nargish ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment (2016), 20(1), 245-256

Detailed reference viewed: 57 (25 ULg)