References of "Roisin, Christian"
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See detailDiversity of Bacterial Communities in a Profile of a Winter Wheat Field: Known and Unknown Members
Stroobants, Aurore ULg; Degrune, Florine ULg; Olivier, Claire et al

in Microbial Ecology (2014)

In soils, bacteria are very abundant and diverse. They are involved in various agro-ecosystem processes such as the nitrogen cycle, organic matter degradation, and soil formation. Yet, little is known ... [more ▼]

In soils, bacteria are very abundant and diverse. They are involved in various agro-ecosystem processes such as the nitrogen cycle, organic matter degradation, and soil formation. Yet, little is known about the distribution and composition of bacterial communities through the soil profile, particularly in agricultural soils, as most studies have focused only on topsoils or forest and grassland soils. In the present work, we have used bar-coded pyrosequencing analysis of the V3 region of the 16S rRNA gene to analyze bacterial diversity in a profile (depths 10, 25, and 45 cm) of a well-characterized field of winter wheat. Taxonomic assignment was carried out with the Ribosomal Database Project (RDP) Classifier program with three bootstrap scores: a main run at 0.80, a confirmation run at 0.99, and a run at 0 to gain information on the unknown bacteria. Our results show that biomass and bacterial quantity and diversity decreased greatly with depth. Depth also had an impact, in terms of relative sequence abundance, on 81 % of the most represented taxonomic ranks, notably the ranks Proteobacteria, Bacteroidetes, Actinobacteridae, and Acidobacteria. Bacterial community composition differed more strongly between the topsoil (10 and 25 cm) and subsoil (45 cm) than between levels in the topsoil, mainly because of shifts in the carbon, nitrogen, and potassium contents. The subsoil also contained more unknown bacteria, 53.96 % on the average, than did the topsoil, with 42.06 % at 10 cm and 45.59 % at 25 cm. Most of these unknown bacteria seem to belong to Deltaproteobacteria, Actinobacteria, Rhizobiales, and Acidobacteria. [less ▲]

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See detailSoil compaction resulting from different soil tillage systems
Destain, Marie-France ULg; Roisin, Christian; Mercatoris, Benoît ULg

in ASABE - CSBE/ASABE Joint Meeting Presentation (2014, July)

The effects of long-term use (8 years) of two different tillage systems were assessed on a Luvisol, under temperate climate (Belgium). The tillage treatments were (i) conventional tillage (CT) with ... [more ▼]

The effects of long-term use (8 years) of two different tillage systems were assessed on a Luvisol, under temperate climate (Belgium). The tillage treatments were (i) conventional tillage (CT) with moldboard ploughing to 27 cm depth and (ii) reduced tillage (RT) with a spring tine cultivator to 10 cm depth. The measurements included bulk density (BD) and precompression stress (Pc) chosen as indicators of mechanical strength, and the pore size distribution (PSD) measured by mercury intrusion porosimetry (MIP). The tillage systems, the depth and their interaction had a significant effect on BD, Pc and PSD. In CT, in the topsoil, the soil strength was low and the total porosity n was about 50 %. In the subsoil, n decreased to 43 %. The PSD of CT was uni-modal in topsoil and subsoil in the MIP measurement range. The mean value of the mode rmax diminished from the topsoil toward the subsoil (from 2.5 microns to 1.9 microns). In RT, in the topsoil, the soil strength was higher than CT. BD did not vary much according to the depth. The total porosity n of RT was comprised between 40-45 % in the soil profile. The PSD was uni-modal and rmax increased from topsoil (around 2 microns) to subsoil (> 3 microns). This suggested the agglomeration of fine particles under the long-term action of mechanical loads, climatic agents, biological organisms or clay minerals acting as cementing agents. These phenomena could be at the origin of the increase of Pc with the depth without significant modification of BD. Such high values of Pc could be responsible of negative effects on root-growth leading to a more superficial root lateral development. [less ▲]

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See detailCoupling X-ray microtomography and macroscopic soil measurements: a method to enhance near saturation functions?
Beckers, Eléonore ULg; Plougonven, Erwan; Gigot, Nicolas et al

in Hydrology & Earth System Sciences (2014), 18

Agricultural management practices influence soil structure, but the characterization of these modifications and consequences are still not completely understood. In this study, we aim at improving water ... [more ▼]

Agricultural management practices influence soil structure, but the characterization of these modifications and consequences are still not completely understood. In this study, we aim at improving water retention and hydraulic conductivity curves using both classical soil techniques and X-ray microtomography in the context of tillage simplification. We show a good match for retention and conductivity functions between macroscopic measurements and microtomographic information. Microtomography highlights the presence of a secondary pore system. Analysis of structural parameters for these pores appears to be significant and offers additional clues for objects differentiation. We show that relatively fast scans supply not only good results, but also enhance near saturation characterization, making microtomography a highly competitive instrument for routine soil characterization. [less ▲]

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See detailX-ray microtomography: A porosity-based thresholding method to improve soil pore network characterization?
Beckers, Eléonore ULg; Plougonven, Erwan ULg; Roisin, Christian et al

in Geoderma (2014), 219-220

X-ray microtomography, through quantification of soil structure at the microscale, could greatly facilitate the current understanding of soil hydrodynamic behaviour. However, binarisation method and ... [more ▼]

X-ray microtomography, through quantification of soil structure at the microscale, could greatly facilitate the current understanding of soil hydrodynamic behaviour. However, binarisation method and processing choices are subjective and can have a strong impact on results and conclusions. In this study, we test a new method based on the porosity detectable by X-ray microtomography, while validation is achieved through comparison of soil microtomogram information with soil physical measurements. These measurements consist of water retention and unsaturated hydraulic conductivity using two different soil populations with only structural differences. To assess the porosity-based method performances, we compare it to four other methods, namely the global method of Otsu and three recent soil-dedicated local methods. The robustness of the porosity-based method is also tested in regard to different pre-processing procedures. In this paper we demonstrate that soil segmentation through a porosity-based method is an interesting issue. Indeed, it is less demanding in terms of time and computational requirements than its alternatives, and combines robustness and performances broadly comparable with the recent local methods. [less ▲]

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See detail4. La fumure azotée
Meza Morales, Walter ULg; Monfort, Bruno; Dumont, Benjamin ULg et al

in Bodson, Bernard; Destain, Jean-Pierre (Eds.) Livre Blanc céréales (2014, February 26)

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See detail10. Perspectives - 2. Perspectives offertes par la culture en association de froment et de pois protéagineux d'hiver
Pierreux, Jérome ULg; Delaplace, Pierre ULg; Roisin, Christian et al

in Bodson, Bernard; Destain, Jean-Pierre (Eds.) Livre Blanc céréales (2014, February 26)

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See detail2. Implantation des cultures
Eylenbosch, Damien ULg; Hiel, Marie-Pierre ULg; Meza Morales, Walter ULg et al

in Bodson, Bernard; Destain, Jean-Pierre (Eds.) Livre Blanc Céréales (2014, February 26)

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See detailHow can long-term experimental plots can help us to understand the sustainability of different phosphorus inputs ?
Renneson, Malorie ULg; dufey, Joseph; Roisin, Christian et al

Poster (2014)

During the last twenty years, we observed a constant reduction of mineral fertilizer use, due to prices increase and environmental awareness, and an increase of crop removal, leading to a phosphorus (P ... [more ▼]

During the last twenty years, we observed a constant reduction of mineral fertilizer use, due to prices increase and environmental awareness, and an increase of crop removal, leading to a phosphorus (P) budget decrease. These changes are feared for a decrease of soil P content, which is already observed in some regions in Wallonia. However, P being an essential element for plant growth, is a such management compatible with yield maintaining? Are the current cropping systems sustainable? To answer to the questions, different studies are made. However, long-term data are rarely available to understand the influence of cropping systems on the soil behavior, leaching risks or to choose adequate indicators of P. To answer to these questions in our soils, 2 experimental plots of the Walloon Agricultural Research Center. These experimental plots were established in 1967 and 1959 in order to evaluate the effect of, respectively, 3 P and K input levels and different organic inputs on the production. Soils samples were taken in plots and analyzed in laboratory. So, different P indicators and edaphic parameters were determined. This study showed that all indicators are coherent with P levels and correlated with yields but no many differences can be shown between fertilizer types. Meanly, zero P-input engenders a decrease of yield of 7%, while a double input increases yield of 2% in comparison to plots with an input corresponding to crop export. So, financially, the zero P-input option is rarely profitable in the long-term and double input of P removed is never financially sustainable. Leaching into deeper soils levels was studied with analysis of deeper horizons which indicated any leaching , even in plots with double inputs. Indeed, soil P contents in depth were similar in these plots than those with no P-inputs or soils under forest cover. So, to conclude, these plots help to study the sustainability of cropping systems in real situations and to determine appropriate management of P. [less ▲]

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See detailPerspectives offertes par la culture en association de froment et de pois protéagineux d’hiver
Pierreux, Jérome ULg; Delaplace, Pierre ULg; Roisin, Christian et al

in Autonomie protéique et biométhanisation à la ferme (2013, November 27)

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See detailFifty years of crop residue management have a limited impact on soil heterotrophic respiration.
Buysse, Pauline ULg; Schnepf-Kiss, Anne-Caroline; Carnol, Monique ULg et al

in Agricultural and Forest Meteorology (2013), 180

The impacts of crop residue management on soil microbial biomass, labile carbon and heterotrophic respiration (HR) were assessed at a long-term experimental site in the Hesbaye region in Belgium. Three ... [more ▼]

The impacts of crop residue management on soil microbial biomass, labile carbon and heterotrophic respiration (HR) were assessed at a long-term experimental site in the Hesbaye region in Belgium. Three treatments, residue export (RE), farmyard manure addition (FYM) and residue restitution after harvest (RR), have been applied continuously since 1959. The soil is a Eutric Cambisol with, in 2010, significantly different total soil organic carbon contents of 4.4, 5.1 and 5.9 kg C m-2 under the RE, RR and FYM treatments, respectively. Manual field HR measurements were carried out during the 2010 and 2012 crop seasons using a dynamic closed chamber system. Microbial biomass, labile C content and metabolic diversity of soil bacteria were assessed in spring 2012. Fifty-one years after the beginning of the treatments, residue management had a limited impact on HR. Based on daily averaged values, the treatment had a significant impact (α = 10%) in 2012 but not in 2010. Based on the individual measurement dates, the treatment impact was less obvious in 2012; with the observation of a significant impact (α = 10%) on HR in only 7% and 36.8% of the measurement dates in 2010 and 2012, respectively. Labile C and microbial biomass were significantly lower in the RE treatment than in FYM and RR. Residue management had no significant effect on cold-water extracted carbon and metabolic diversity of heterotrophic soil bacteria. The limited impact of residue management on HR could be explained by (i) the relatively low amounts of recent above-ground crop inputs, (ii) the large proportion of below-ground residues and other non-exportable above-ground residues reducing the potential differences between treatments and (iii) the relatively large spatial variability of HR. In conclusion, carbon losses due to heterotrophic respiration did not differ between RE, FYM and RR treatments in the studied soil. This contrasts with the different soil organic carbon contents observed in these three treatments after fifty years of experiment. Further investigations regarding the reduction of spatial variability and the potential roles played by organic matter protection within aggregates and biochemical composition of inputs are needed. [less ▲]

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See detailImplantation des cultures
Eylenbosch, Damien ULg; Roisin, Christian; Monfort, Bruno et al

in Destain, Jean-Pierre; Bodson, Bernard (Eds.) Livre Blanc Céréales (2013, September 12)

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See detailHow can long-term experimental plots can help us to understand the sustainability of different phosphorus inputs ?
Renneson, Malorie ULg; Dufey, Joseph; Roisin, Christian et al

Poster (2013, September)

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See detailFifty years of contrasted residue management of an agricultural crop: impacts on the soil carbon budget and on heterotrophic respiration.
Buysse, Pauline ULg; Roisin, Christian; Aubinet, Marc ULg

in Agriculture, Ecosystems & Environment (2013), 167

Crop management exerts a strong influence on the soil carbon (C) balance. This study investigated a long-term experiment initiated in 1959 at a site in the Hesbaye region of Belgium and focused on three ... [more ▼]

Crop management exerts a strong influence on the soil carbon (C) balance. This study investigated a long-term experiment initiated in 1959 at a site in the Hesbaye region of Belgium and focused on three contrasted treatments: residue export (RE), farmyard manure (FYM) addition and residue restitution (RR) after harvest. The objectives were to quantify the components of the C budget of croplands from a 50-year perspective and to identify the impact of the treatments on this budget and soil C sequestration, given the relatively low levels of esidue application. The soil C budget was calculated for each treatment on the basis of total soil organic C (SOC) content measurements and C input data collected since the experiment had begun and drawn from the literature. To evaluate the robustness of this approach, the budget-based output estimates were compared with annual heterotrophic respiration (HR) averages extrapolated from seasonal field HR measurements carried out at the same experimental site in 2010. The soil C budgetbased output estimates accorded well with field-based HR measurements and with most HR estimates in the literature, suggesting that, despite the many uncertainties affecting the soil C budget, these results were robust. The three treatments investigated in this study had different impacts on SOC stocks, mainly during the first 20 years of the experiment. RE and FYM caused significant SOC decreases (on average, −7 ± 5 g C m−2 year−1 over the 50 years) and increases (10 ± 5 g C m−2 year−1), espectively, whereas RR had no significant impact on the SOC stocks. The study also showed (i) the very large part (about twothirds of the total input) that represented the below-ground input, weeds and other left-over residues in the C budget, (ii) the important role probably played by residue quality in C sequestration and (iii) the large proportion of C lost annually rom the soil (which represents 93–98, 100 and 102–107% of the amounts of fresh residue rought to the soil each year in the FYM, RR and RE treatments, respectively). [less ▲]

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See detail3. Contrôle des populations de mauvaises herbes
Jaunard, Delphine ULg; Monty, Arnaud ULg; Mahy, Grégory ULg et al

in Bodson, Bernard; Destain, Jean-Pierre (Eds.) Livre Blanc - Céréales (2013, February 27)

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See detail4. La fumure azotée
Meza Morales, Walter; Monfort, Bruno; Dumont, Benjamin ULg et al

in Bodson, Bernard; Destain, Jean-Pierre (Eds.) Livre Blanc - Céréales (2013, February 27)

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See detail2. Implantation des cultures
Eylenbosch, Damien ULg; Pierreux, Jérome ULg; Dufranne, Delphine et al

in Bodson, Bernard; Destain, Jean-Pierre (Eds.) Livre Blanc - Céréales (2013, February 27)

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See detailImpact of the depth on bacterial diversity in an agricultural soil
Stroobants, Aurore ULg; Degrune, Florine ULg; Lambert, Christophe et al

Poster (2013, February 08)

Bacteria are the most abundant and diverse microorganisms in soils. They play an important role in soil formation, contribute to plant nutrition and are involved in various processes in agroecosystems ... [more ▼]

Bacteria are the most abundant and diverse microorganisms in soils. They play an important role in soil formation, contribute to plant nutrition and are involved in various processes in agroecosystems such as nutrient cycling. The aim of this study was to evaluate the impact of the depth on bacterial diversity and quantity in an agricultural soil. Samples was collected on May 2011 and May 2012 at three different depths : 10, 25 and 45 centimeters. The quantity of total bacteria was measured by real time PCR and the analysis of the diversity was performed by the high throughput sequencing technology. Results obtained by these methods show that the biomass and the bacterial quantity and diversity (Shannon index) decrease with the depth, particularly at 45 centimeters. The biomass is, in average, 6.5 fold less important at 45 cm than at 10 cm and the quantity is 17 fold lower at 45 cm than at 10 cm. Our results also indicate that many taxa, such as Betaprotebacteria, Deltaproterobacteria, Gammaproteobacteria, Acidobacteria and Burkholderiales are influenced by the depth. The results will be presented in more details on the poster. [less ▲]

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See detailIMPACT OF DEPTH AND SOIL COMPACTION ON BACTERIAL DIVERSITY IN SOIL
Stroobants, Aurore ULg; Degrune, Florine; Olivier, Claire et al

Poster (2012, August 19)

Bacteria are the most abundant and diverse microorganisms in soils. The amount of bacteria in soils can reach 10^10 cells per gram of soil. These organisms are involved in various processes in ... [more ▼]

Bacteria are the most abundant and diverse microorganisms in soils. The amount of bacteria in soils can reach 10^10 cells per gram of soil. These organisms are involved in various processes in agroecosystems such as nutrient cycling, contributing to plant nutrition, plant health and soil structure. The knowledge about this diversity is limited because only one percent of these organisms can be cultured by laboratory methods. During the last decades, many molecular-based techniques have been developed to assess the diversity of bacterial communities. The aim of this study was to determine the quantity and diversity of bacteria in two agricultural soils with differents soil management practices (tillage and no tillage) at different depths (10, 30 and 45 centimeters) and different compaction levels (high and low). Quantity was evaluated by real time PCR and diversity was analysed by the DGGE (Denaturing Gradient Gel Electrophoresis) technique. The results show that soil management has an impact on bacterial quantity at 45 centimeters and quantity is higher in till soil. Compaction level affects the bacterial quantity in till soil, quantity is higher in low compaction. And finally, depth influences the bacterial quantity in till and no till soil. In both soils, quantity decreases with the depth. The results will be presented and discussed on the poster. [less ▲]

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See detailSoil carbon budget of a 50-year residue management experiment in a Belgian cropland.
Buysse, Pauline ULg; Roisin, Christian; Aubinet, Marc ULg

Conference (2012, July 06)

Within the context of Climate Change, crop management exerts a strong influence on the soil carbon (C) balance. This study aims (1) to estimate the C loss by soil heterotrophic respiration (SHR) in ... [more ▼]

Within the context of Climate Change, crop management exerts a strong influence on the soil carbon (C) balance. This study aims (1) to estimate the C loss by soil heterotrophic respiration (SHR) in different residue management treatments through the establishment of their soil C budgets and (2) to compare these estimations with field SHR measurements. Three contrasted treatments were considered: Residue Export (RE), Farm Yard Manure addition (FYM) and Residue Restitution after harvest (RR). They were established in 1959 and continuously applied since then at an experimental field located in the Hesbaye region in Belgium. The soil C budget was calculated for each treatment on the basis of total soil organic C content measurements and C input data compiled since the beginning of the experiment. This allowed estimating the C loss by SHR in the different treatments. SHR measurements were performed in 2010 and 2011 to compare them with the budget-based estimations and to assess SHR sensitivity to temperature in the different treatments. The soil C budgets showed that the soil under the RR treatment was likely to undergo the biggest C loss by SHR since the beginning of the experiment. The SHR field measurements, performed 50 years after the experiment had begun, did however not show any significant difference between the SHR rates in the three treatments. Laboratory investigations (microbial biomass, basal respiration, metabolic diversity and soil fractionation) will be performed to better understand the effects of long-term residue management on soil C dynamics. [less ▲]

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