Consequences of slotting on the pore characteristics of a sandy soil in northeast Thailand |
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Authors: | C. Hartmann,,G. Lesturgez,,P. Sindhusen,,S. Ratana-Anupap,V. Hallaire,,A. Bruand, & R. Poss |
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Affiliation: | French Research Institute for the Development (DRV-UR176 Solutions), Ecole Normale Supérieure (ENS), Laboratoire BIOEMCO, 46 rue d'Ulm, 75230 Paris Cedex 05, France;, French National Institute for Agronomical Research, Unitéde Science du Sol, Route de St Cyr, 78026 Versailles, France;, Land Development Department, Office of Science for Land Development, Paholyothin Road, Chatuchak, Bangkok 10900, Thailand;, French National Institute for Agronomical Research, UMR Sol Agronomie Spatialisation, 65 route de Saint-Brieuc, 35042 Rennes Cedex, France;, Institut des Sciences de la Terre d'Orléans (UMR 6113), Universitéd'Orléans, CNRS, 1A Rue de la Férollerie, 45071 Orléans Cedex 2, France;, and French Research Institute for the Development (DRV-UR176 Solutions), SupAgro, 2 place Viala, 34060 Montpellier Cedex 1, France |
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Abstract: | In the sandy soils of northeast Thailand, root development is generally limited to the topsoil (0–20 cm depth) but a simple slotting intervention (20–40 cm) significantly increased the root frequency in the slotted material (Eslot) compared with the undisturbed subsoil (E horizon). The aim of this study was to investigate the consequences of slotting on the soil structure by analysing at different scales the pore characteristics of the original soil profile and of the soil material inside the slot. These characteristics were studied using bulk density measurements, image analysis of thin sections and mercury porosimetry. Our results showed that the total porosity of the E horizon and Eslot material was similar when measured in 100 cm3 cylinders, but that the pore size distribution had been changed by slotting. The unaltered E horizon contained mainly small pores characterized by a narrow distribution related to close packing of the sand grains, associated with some biological macropores probably with poor continuity as they did not contain roots despite their size. On average, pores were larger in the Eslot material, with a broader distribution resulting from looser packing of the sand grains but with fewer biological macropores. Although slotting reduced the number of biological pores, the looser packing appeared to be more favourable to root development than the presence of macropores in the E horizon. Finally, the comparison of the porosity in the different horizons with the porosity of the Eslot material, indicated the significance of the closeness of the sand packing on root development. |
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Keywords: | Sandy loam compaction soil slotting bulk density image analysis mercury porosimetry |
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