Poster (Scientific congresses and symposiums)
Impacts of wheel traffic on the physical properties of a Luvisol under reduced and conventional tillage
Saur, Marie-Laure; Destain, Marie-France; Roisin, Christian et al.
2016Day of the Young Soil Scientist
 

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Saur M.-L., Destain M.-F., Roisin C., Mercatoris B..ppt
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Keywords :
soil compaction; conventional tillage; reduced tillage; bulk density; precompression stress; pore size distribution; automatic cone index; Cam-Clay; wheel traffic
Abstract :
[en] Soil compaction is a complex mechanism which results in a decrease of soil porosity and an increase of soil strength. Such effects may reduce crop yield since they are harmful for root growth, germination, mesofauna and bacterial life. Soil compaction may also reduce hydraulic conductivity which increases the risk of runoff, contamination of surface water, erosion and emission of greenhouse gases due to anaerobic processes. In the context of sustainable agriculture, it is crucial to characterise the impact of the agricultural techniques on the compaction state in the arable layer due to machine traffic. For this purpose, Soil samples were taken in a Luvisol at different depths, on plots under longterm reduced tillage (RT) and conventional tillage (CT). The impact of wheel traffic on the physical properties of the soils was also studied. The experimental approach consists in measuring traditional macroscopic soil properties such as bulk density and precompression stress, and combining them with pore size distribution obtained by mercury intrusion porosimetry. Automatic cone index measurements were initially performed to map the soil resistance and easily identify the sampling depths. The measurements revealed a plough pan at 30-cm depth under both CT and RT. Nevertheless, the subsoil under RT showed pieces of evidence of a natural regeneration process of the microporosity. The impact of wheel traffic was studied in RT and CT plots. It was shown that the passage of heavy machine such as beet harvester coupled to water content close to the optimum proctor is clearly unfavourable in terms of compaction. The measurements revealed large modifications of soil structure in the topsoil of CT, whereas the soil structure slightly changes through depth. However, the latter remains the more problematic case since the soil will not be loosened by tillage anymore, resulting in strongly compacted soil years after years. In addition to the experimental approach, numerical modelling was used in order to predict the soil compaction. A finite element method was used and the soil behaviour was modelled by an elastoplastic law (modified Cam-Clay model). The model parameters were calibrated from the experimental measurements. The simulations allowed to compare the porosity and the surface deformation after wheel traffic with the experiments. The variations of machine weight and tyre pressure were numerically studied and it was showed that the machine weight has an influence in the topsoil and the subsoil, whereas the tyre pressure affects only the topsoil.
Research center :
Gembloux Agro-Bio Tech, Université de Liège
Disciplines :
Agriculture & agronomy
Author, co-author :
Saur, Marie-Laure ;  Université de Liège > Ingénierie des biosystèmes (Biose) > Agriculture de précision
Destain, Marie-France ;  Université de Liège > Ingénierie des biosystèmes (Biose) > Agriculture de précision
Roisin, Christian;  Walloon Agricultural Research Centre > Department of Agriculture and Natural Environment
Mercatoris, Benoît  ;  Université de Liège > Ingénierie des biosystèmes (Biose) > Agriculture de précision
Language :
English
Title :
Impacts of wheel traffic on the physical properties of a Luvisol under reduced and conventional tillage
Publication date :
2016
Number of pages :
A0
Event name :
Day of the Young Soil Scientist
Event place :
Bruxelles, Belgium
Event date :
mercredi 16 mars 2016
Funders :
Région wallonne [BE]
Available on ORBi :
since 12 May 2016

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