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See detailImpact of stone content on soil moisture measurement with capacitive sensors 10HS (Decagon)
Deraedt, Deborah ULg; Bernard, Julien ULg; Biettlot, Louise ULg et al

in Geophysical Research Abstracts (2015), 17

Lot of soil survey focused on agricultural soils. For practical reasons, those soils have a low stone content. So, most of the soil water content sensors are placed on low stone content soils and the ... [more ▼]

Lot of soil survey focused on agricultural soils. For practical reasons, those soils have a low stone content. So, most of the soil water content sensors are placed on low stone content soils and the calibration equations are developed for them. Yet some researches take an interest in forest soils that are often much different from the previous ones. The differences lie in their stone content and their slope. Lots of studies have proved the importance of making soil specific calibration of the soil water content sensor. As our lab use regularly the 10HS sensors (Decagon Devices, United States) in forested soil, we decided to evaluate the importance of the stone content in the soil moisture measurement. The soil used for this experimentation comes from Gembloux (50◦33’54.9”N, 4◦42’11.3”E). It is silt that has been sieved at 2 mm to remove the gravel. The stones used to form the samples come from an experimental site located in the Belgian Ardennes (50◦1’52.6”N, 4◦53’22.5”E). They are mainly composed of schist with some quartz and sandstone elements. Initially, only five samples were constructed with three replications each. The size and the proportion of stones were the variables. Stones were classified in two groups, the first contains gravels whose size is less than 1,5 cm and a the second contains gravels whose size is comprised between 2 and 3 cm. The proportions of stone selected for the experiment are 0, 20 and 40%. In order to generate validation data, two more samples were constructed with intermediate proportion of stone content (30%). The samples were built in PVC container which dimensions are slightly bigger than the sensor volume of influence (1.1-1.3l). The soil samples were saturated and then dried on a thermal chamber set at about 32◦C. During at least 14 days, the samples soil water content was determined by the sensor measurement with the Procheck read-out system (Decagon Devices, United State) and by weighting the samples thrice a day. The evolution of the soil sample height was monitored as well. As first result, the stone content is a parameter that seems to influence soil water content. The stone size is no important. Because soil moisture deserves to be measured accurately in every soil and to confirm the first results the experiment is going on with more samples, different stone proportions, other sensor positioning and a natural air drying. [less ▲]

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See detailDiachronical soil surveys: a way to quantify long term diffuse erosion
Pineux, Nathalie ULg; Michel, Brieuc ULg; Legrain, Xavier ULg et al

in Geophysical Research Abstracts (2015), 17

The loess belt of Western Europe is a high-risk area regarding diffuse erosion. It is due to the climate and the topography but also to the soil type. Loamy soils are naturally highly sensitive to diffuse ... [more ▼]

The loess belt of Western Europe is a high-risk area regarding diffuse erosion. It is due to the climate and the topography but also to the soil type. Loamy soils are naturally highly sensitive to diffuse erosion. Hence, these soils are very fertile. So, they are intensively cultivated which increases their sensitivity to erosion. Sheet erosion is an erosion type strongly represented in these regions. Contrarily to the concentrated form of erosion which happens more brutally, sheet erosion needs long-term observation time-scales, which remains rare. In Belgium, a soil map was established in 1956. This map is quite detailed and notably informs about the different horizons which are in the profile (ploughed horizon, eluvial horizon, clay included between the horizons, carbonate-free loess horizon, and all these were characterised by drainage class) and their depth. It was based on a dense augering network across the country (one point every 75 meters). A new augering campaign was done again in 2014. It consisted in one observation every 50 meters on an agricultural watershed of 124 hectares located in the centre of Belgium. This catchment has been cultivated since the 14th century and is representative of the local context (gentle slope (3-8%), plot size (mean value of 10 ha), …). We compared the two soil maps produced on this site with a 58years time lapse. Results show that the large majority of the watershed falls from upslope soils with weak erosion to slope soils with strong erosion. The soil thickness diminished in some zones to 1m10 (minimum estimation) of erosion. This comparison shows that very few upslope soils are preserved. On the other hand, the areas where colluviums were present to the full depth stay at the same place in the main thalweg of the watershed. Other areas on the watershed seem to be subject to a (minimum estimation) of 40cm of sediments deposition. Large areas in the watershed suffered from erosion and came to deposition areas as the clay horizon is no longer observed under the colluviums. It can be highlighted that soil depths were worryingly lost during 58 years of tillage and that some soils were converted to colluviums which is of lower agronomical quality than the original soils which had a clay horizon below to keep water. Diachronical soil survey offers an unique insight of long term diffuse erosion and should demonstrate the importance of preserving soils even in regions where agricultural yields are not (yet) affected by erosion. [less ▲]

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See detailContact resistance problems applying ERT on low bulk density forested stony soils Is there a solution?
Deraedt, Deborah ULg; Touzé, Camille; Robert, Tanguy et al

in Geophysical Research Abstracts (2015), 17

Electrical resistivity tomography (ERT) has often been put forward as a promising tool to quantify soil water and solute fluxes in a non-invasive way. In our experiment, we wanted to determine ... [more ▼]

Electrical resistivity tomography (ERT) has often been put forward as a promising tool to quantify soil water and solute fluxes in a non-invasive way. In our experiment, we wanted to determine preferential flow processes along a forested hillslope using a saline tracer with ERT. The experiment was conducted in the Houille watershed, subcatchment of the Meuse located in the North of Belgian Ardennes (50˚1’52.6”N, 4˚53’22.5”E). The climate is continental but the soil under spruce (Picea abies (L.) Karst.) and Douglas fire stand (Pseudotsuga menziesii (Mirb.) Franco) remains quite dry (19% WVC in average) during the whole year. The soil is Cambisol and the parent rock is Devonian schist covered with variable thickness of silty loam soil. The soil density ranges from 1.13 to 1.87 g/cm3 on average. The stone content varies from 20 to 89% and the soil depth fluctuates between 70 and 130 cm. The ERT tests took place on June 1st 2012, April 1st, 2nd and 3rd 2014 and May 12th 2014. We used the Terrameter LS 12 channels (ABEM, Sweden) in 2012 test and the DAS-1 (Multi-Phase Technologies, United States) in 2014. Different electrode configurations and arrays were adopted for different dates (transect and grid arrays and Wenner – Schlumberger, Wenner alpha and dipole-dipole configurations). During all tests, we systematically faced technical problems, mainly related to bad electrode contact. The recorded data show values of contact resistance above 14873 Ω (our target value would be below 3000 Ω). Subsequently, we tried to improve the contact by predrilling the soil and pouring water in the electrode holes. The contact resistance improved to 14040 Ω as minimum. The same procedure with liquid mud was then tested to prevent quick percolation of the water from the electrode location. As a result, the lower contact resistance dropped to 11745 Ω. Finally, we applied about 25 litre of saline solution (CaCl2, 0.75g/L) homogeneously on the electrode grid. The minimum value of contact resistance reduced to 5222 Ω. This improved the contact resistance substantially, but complicates the execution of a pulse tracer experiment. To date we did not find any better solution to this problem and we keep searching a way to improve the contact resistance in stony forested soils with very low bulk density. We would like to exchange on these questions with EGU attendees in order to improve the experimental design or point out a new research path for these specific conditions. This could lead to enhance the use of ERT in soils with low density and high stone content. [less ▲]

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See detailModeling of cobalt and copper speciation in metalliferous soils from Katanga (Democratic Republic of Congo)
Pourret, Olivier; Lange, Bastien; Houben, David et al

in Journal of Geochemical Exploration (2015), 149

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See detailDoes the cover crop residue management affect the soil water availability for plants?
Chelin, Marie ULg; Parvin, Nargish ULg; Hiel, Marie-Pierre ULg et al

Poster (2014, December 05)

Hydraulic processes and soil storage capacity may be affected by the crop residue management. Thus, a better understanding of the spatial and temporal distribution of water as a consequence of different ... [more ▼]

Hydraulic processes and soil storage capacity may be affected by the crop residue management. Thus, a better understanding of the spatial and temporal distribution of water as a consequence of different tillage methods is needed. The distribution of soil water content is basically studied thanks to soil moisture sensors such as time domain reflectometry (TDR) probes. However, this method requires the disturbance of the soil and only provides local information. Comparatively, electrical resistivity tomography (ERT) slightly alters the soil structure. It has been considered as a proxy to assess the spatial and temporal variability of the soil water content. This study aims at assessing whether and to which extent the crop residue management influences soil water dynamics and the water availability for maize. Water content will be monitored from March to October 2014, under three crop residue managements: conventional tillage realized in the end of autumn, conventional tillage realized just before sowing, and strip tillage. A bare soil under conventional tillage will also be monitored so as to better understand the influence of the plant over the growing season. So as to better understand the dynamics of water in the soil-water-continuum, the influence of the crop residue management on the soil structure and the plant development will also be investigated. The soil water pattern will be daily monitored on a surface of two square meters through surface stainless steel electrodes, corresponding to three rows of seven maize plants. Five additional sticks with buried electrodes will be setup to get more detailed information near to the maize row. For each of the monitored zone, two TDR probes will help validating the data. In order to calibrate the relationship between electrical resistivity and soil water content, a dig will be dug, in which a set of four electrodes, one TDR probe and one temperature sensor will be placed at four different depths. Two suction cups placed on each of the monitoring zone will help getting the electrical conductivity of the soil solution. [less ▲]

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See detailBioRefine Project: Detection of bioavailability of Metallic Trace Elements in soils by the use of microbial biosensors
Tarayre, Cédric ULg; Hurdebise, Quentin ULg; Fischer, Christophe ULg et al

Poster (2014, September 09)

Zinc, lead and cadmium are the main Metallic Trace Elements (MTEs) found in soils contaminated by the mining industry in Europe. MTEs are spread in the environment because of the disruption of ... [more ▼]

Zinc, lead and cadmium are the main Metallic Trace Elements (MTEs) found in soils contaminated by the mining industry in Europe. MTEs are spread in the environment because of the disruption of biogeochemical cycles caused by human activities. Due to their low mobility and biodegradability, they accumulate in soils where they are strongly bound to particles. It has become necessary to understand interactions between MTEs and the environment and to implement remediation actions. This work is focused on remediation monitoring techniques by using whole cell microbial biosensors able to detect zinc, lead and cadmium. Biosensors provide a signal in response to the bio-available concentration in MTEs, which are valuable for the design of efficient techniques involving bioremediation. Whole cell biosensors used in this work are based on Escherichia coli strains carrying a fluorescent reporter system. The reporter element contains a promoter sensitive to MTEs and a gene coding for the Green Fluorescent Protein (GFP). MTEs activate the synthesis of GFP, which is a very stable protein, causing the accumulation of GFP inside the cells. Then, fluorescence can be measured by flow cytometry. In this study, two biosensors were investigated: E. coli pPzraPgfp and E. coli pPzntAgfp. The last strain provided a linear response to zinc up to 20 mg/l and a curvilinear response to cadmium up to 0.15 mg/l. No detection was highlighted regarding lead. In practical cases, soils and wastes are contaminated by several types of MTEs. Consequently, combined contaminations were also tested. This work allowed highlighting that the strain E. coli pPzntAgfp can be used to assess the bioavailability of cadmium in soils, although the experimental procedure must be improved. This work is supported by the BioRefine Project, a European project in which various member states focus on recovery of inorganics from organic wastestreams. We gratefully acknowledge the INTERREG IVB NWE programme, which financed the BioRefine Project (ref. 320J-BIOREFINE). [less ▲]

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See detailImpacts of biostimulant products on the growth of wheat and the microbial communities of its rhizosphere under contrasted production systems
Nguyen, Minh ULg; Bodson, Bernard ULg; Colinet, Gilles ULg et al

Poster (2014, August 24)

Plant growth-promoting rhizobacteria (PGPR) are one of the major biostimulant classes due to their ability to stimulate root growth, enhance mineral availability, and nutrient use efficiency in crops ... [more ▼]

Plant growth-promoting rhizobacteria (PGPR) are one of the major biostimulant classes due to their ability to stimulate root growth, enhance mineral availability, and nutrient use efficiency in crops. PGPR-containing biostimulant products could therefore make agriculture more sustainable by reducing demand for chemical fertilizer and lessen their negative environmental impacts. The aim of this project is to screen PGPR strains to (1) enhance wheat fitness level (growth, photosynthesis efficiency, stress tolerance, and yield) in combination with an optimised fertilizer level, (2) stimulate the increase in beneficial microorganism communities and suppress pathogenic ones in the wheat rhizosphere, (3) link wheat productivity to the composition of the microbial communities found in its rhizosphere, and (4) measure the impacts of such changes on soil fertility. A list of PGPR-containing biostimulants have been collected from screening, including several commercially available products (e.g. TwinN and NitroGuard, Mabiotec; Rhizocell GC, Ithec; B. subtilis FZB24 fl and Rhizo Vital 42, Abitep) as well as newly discovered PGPR strains. The biostimulants from that list have been screened in greenhouse and we expect to obtain results within next month. In parallel, several levels of nitrogen supply have been tested in combination with biostimulants to optimize agricultural practices and achieve the highest yield on field condition. A soil analysis protocols will also be built up to measure the influence of those PGPR strains on soil fertility changes and root uptake efficiency. In order to assess changes in the rhizomicrobial communities including fungi and bacteria (either pathogenic, neutral, or beneficial) under controlled or field conditions, metagenomic approaches will be set up. Finally, a maximum of three promising PGPR strains will be selected for practical agronomical application in larger field trials. [less ▲]

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See detailWhich P inputs are compatible with a sustainable agriculture at short and long-term?
Renneson, Malorie ULg; Dufey, Joseph; Roisin, Christian et al

Poster (2014, August)

During the past 20 years, there has been a constant reduction in mineral fertilizer use due to price increases and environmental concerns. These changes can lead to a decrease in soil P content, which is ... [more ▼]

During the past 20 years, there has been a constant reduction in mineral fertilizer use due to price increases and environmental concerns. These changes can lead to a decrease in soil P content, which is already observed in some regions in Wallonia. Some new issues are now emerging. Is current cropping systems compatible with yield maintenance? Do organic fertilizers have a similar effect than mineral fertilizers? To answer to these questions, a short-term experiment in controlled conditions and 2 long-term experimental plots were studied. The short-term experiment permitted to study the kinetics of P after an input and differences between fertilizer types, whereas the long-term experiments studied 3 levels of P and K input and different organic compounds. Although an evolution of P content was observed, no difference of yield was found before about 20 years. However, after 47 years, available P levels were considered as low in zero P-input plots and attention must now be focused on these parcels. Zero P-input caused a mean yield decrease of 7%, while a double input increased yield by 2% in comparison to plots with input corresponding to crop export. Thus the zero P-input option is rarely economically profitable in the long-term and providing double the amount of P removed is never financially sustainable. Finally, no difference of P content was observed between organic and mineral fertilizers, except for manure which engendered a higher P content. In conclusion, organic and inorganic fertilizers had a relatively similar effect and overlooking P fertilizer is possible in the short-term but P content has to be followed at the long-term, although yield loss was limited. [less ▲]

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See detailPrediction of stock and fate of phosphorus forms according to soil classification
Renneson, Malorie ULg; Barbieux, Sophie ULg; Dufey, Joseph et al

Poster (2014, August)

Wallonia presents a high diversity of soils and the fate of P in the soil-plant systems can highly vary from one region to another. The fate of phosphorus depends upon its forms in the solid constituents ... [more ▼]

Wallonia presents a high diversity of soils and the fate of P in the soil-plant systems can highly vary from one region to another. The fate of phosphorus depends upon its forms in the solid constituents of soils, which is seldom characterized. For example, total P determines the soil reserve of P but also the potential P content which can be lost to surface water by erosion but analysis of this parameter is time consuming and rarely performed. This study aims (i) to define functional groups of soils for a differentiate P management, (ii) to estimate total soil P by regression equations based on soil parameters, and (iii) to estimate the quality of these predictions. The study consists in a characterization of 12 parent materials in Wallonia, collected across different land uses. A classification of soils was defined by clustering analysis and 5 groups were defined according to P contents and forms. Using this information in regression improved the quality of predictions. The coefficients of determination vary from 0.83 to 0.99, in comparison to a coefficient of 0.77 for the global regression. Then, pedotransfer functions were validated with an independent external dataset of 55 soils. Estimation of the quality of the prediction of P content (mean error, standard deviation of prediction and root mean square error) was made with global and local regression models. In conclusion, using a soil classification allowed to improve P content assessment by specific regressions and to propose differentiated P management for each group of soils. [less ▲]

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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 detailLa Carte des Sols de la Belgique : un héritage à se réapproprier
Legrain, Xavier ULg; Michel, Brieuc ULg; Bock, Laurent ULg et al

Conference (2014, July 03)

Une cartographie systématique à grande échelle des sols de Belgique a été conduite entre 1947 et 1991. Les observations étaient effectuées au moyen de sondages à la tarière jusqu’à une profondeur standard ... [more ▼]

Une cartographie systématique à grande échelle des sols de Belgique a été conduite entre 1947 et 1991. Les observations étaient effectuées au moyen de sondages à la tarière jusqu’à une profondeur standard de 125 cm dans la mesure du possible, avec une densité moyenne de 2 sondages à l’hectare. Des plans cadastraux au 1/5 000 ont servi à noter les observations et à tracer les limites des plages cartographiques, généralisées par la suite par transcription sur fond de carte topographique au 1/10 000. La carte finale a été publiée par planchettes à l’échelle du 1/20 000, associées à des livrets explicatifs. La carte s’appuie sur une légende originale, basée majoritairement sur des critères morphologiques du sol, aisément identifiables sur le terrain, objectifs (sans a priori d’interprétation) et les plus permanents possibles. La combinaison de ces critères, transcrits en symboles alphanumériques, est à l’origine de la très grande richesse sémantique de la légende, forte de plus de 10 000 unités cartographiques de sols. La numérisation de la Carte des Sols de la Belgique et la structuration de l’information délivrée par la légende ont ouvert de nombreuses perspectives en terme d’applications. Mais au-delà du produit final qu’est la carte, le véritable héritage légué est l’extraordinaire connaissance experte accumulée par les cartographes durant la durée du projet. Si une part inestimable de ce savoir s’en est allée en même temps qu’eux, une part tangible est accessible à travers de nombreuses publications (livrets explicatifs, monographies, thèses, articles) ou parsème divers documents d’archive (notes de terrain, PV de réunion, rapports d’excursions). Ces derniers sont également une invitation à se replonger dans le contexte historique, scientifique et philosophique de l’époque des levés. Ils permettent de ce fait de mieux cerner la manière dont la légende a été pensée, élaborée, adaptée, remaniée. L’éclairage que ces publications et documents d’archive donnent sur la carte et sa légende laisse entrevoir une richesse d’information insoupçonnée. Se la réapproprier par une interprétation avertie de la carte est essentiel préalablement à toute valorisation. Cette communication se propose de justifier l’intérêt de cette démarche au travers de multiples exemples. Ils ont été choisis de manière (i) à présenter la diversité des cas rencontrés et (ii) à illustrer l’impact d’une telle interprétation sur la qualité des produits issus de 2 projets menés actuellement : la corrélation de la légende de la Carte des Sols de la Belgique avec le système de classification international World Reference Base et la contribution belge au projet mondial GlobalSoilMap. [less ▲]

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See detailSoil infrastructure evolution and its effect on water transfer processes under contrasted tillage systems - overview of methodologies with preliminary results
Parvin, Nargish ULg; Colinet, Gilles ULg; Garré, Sarah ULg et al

Conference (2014, June 10)

The heterogeneity of soil structure and porosity are highly influenced by external factors like tillage systems and other land management approaches. The aim of this project is to investigate the effect ... [more ▼]

The heterogeneity of soil structure and porosity are highly influenced by external factors like tillage systems and other land management approaches. The aim of this project is to investigate the effect of soil tillage along with residue management on the changing pattern of soil structure. This investigation will help to emphasize the different water flow dynamics especially the preferential flow processes through the soil that are influenced by the changes in structural distribution in the soil profile. The experimentation has been started from June 2013 in the research field in Gembloux. Soil profile description together with soil sampling has been carried out in the four objects of land management. Soil samples will be used for the measurement of water retention capacity (done), hydraulic conductivity and x-ray microtomography. The assessment of soil water retention curves with pressure plate technique show significantly (p<0.05) higher water retention (Hwr) in WP than ST at 9.8 to 98 hPa, Hwr in WP than NI at 39 to 14710 hPa, Hwr in ST than NI at 294 to 14710 hPa and Hwr in WP than NO at 69 to 98 hPa. There was no significant difference in the water retention between NO and NI and ST and NO. Since, tillage practices generally increase soil porosity, the correlation between soil hydraulics and porosity distribution would expect to be different for different tillage systems. In our study, WP retains more water due to the increase of macroporosity than ST, NI and NO. As the changes in soil structure are usually noticed in the range of 9.8 to 98 hPa, so, we can conclude that there is certainly structural change between WP and conservation practices of ST, NI and NO. In our study, there will be also soil moisture sensors (Decagon 10HS, 5TM and ML3 Thetaprobe) to capture the total soil moisture networks in the field under four different trials. The soils from the different trials and also from different depths (0-15, 25-30 and 50-60 cm) were used for zone specific calibration of the sensors. All the experiments will be repeated twice a year. For the specific spatio-temporal comparison, the monitoring results from electrical resistance tomography will be available from the collaborated project of the same faculty. [less ▲]

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See detailEffects of tillage practices and crop residue exportation on earthworm communities and soil physico-­chemical properties in silt loam arable soil (Belgium)
Lemtiri, Aboulkacem ULg; Colinet, Gilles ULg; Alabi, Taofic ULg et al

Poster (2014, June 08)

Earthworms are known to play integral roles in soils, and are often referred to as vital soil and ecosystem engineers due to their capacity to influence a wide range of chemical, physical, and biological ... [more ▼]

Earthworms are known to play integral roles in soils, and are often referred to as vital soil and ecosystem engineers due to their capacity to influence a wide range of chemical, physical, and biological properties of soil environments. Therefore, it is important to understand how earthworm communities are impacted by tillage systems and crop management practices. In the present study, earthworm and soil samples were collected from wheat cultivated fields in Gembloux, Belgium under the following four experimental treatments: (1) conventional tillage with crop residues left in the soil (CT/IN); (2) conventional tillage with crop residues removed from the field (CT/OUT); (3) reduced tillage with crop residues left in the soil (RT/IN); and (4) reduced tillage with crop residues removed from the field (RT/OUT). The different tillage systems were applied for four consecutive years prior to the initiation of the current study. Results indicated soil compaction was significantly higher in RT compared with CT up to a depth of 6–49 cm. Significant differences were not detected between residue incorporation depth systems, where results showed mean earthworm abundance was respectively 182.25 and 180 individuals.m-2 in CT and RT. Mean earthworm biomass was similarly not significantly different between CT and RT, where results were respectively 48.52 and 57.27 g.m-2. However, a significant difference was observed between IN and OUT treatments, suggesting the exportation of wheat residues will limit earthworm abundance and biomass in CT and RT plots. Data showed high representation of the endogeic earthworm ecological category, notably N. c. caliginosus regardless of treatment. Despite tillage system and exportation of crop residues, N. c. caliginosus, L. terrestris, and A. r. rosea exhibited high abundance, indicating tolerance to soil environmental conditions. For each depth, measures of soil physico-chemical properties showed significant differences among treatments. Furthermore, soil chemical property attributes were significantly higher in the first soil centimetres compared to lower soil layers. These results were attributable to earthworm activity and wheat residues, suggesting earthworms contributed to nutrient dynamics, particularly at increased soil depths. Overall, the results emphasise the influence of exportation of crop residues on earthworm community and also, the important influence of earthworm activity on soil physico-chemical properties change, processes which are closely linked. [less ▲]

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