Soil Thermal Conductivity as Influenced by Aggregation at Intermediate Water Contents
- Zhaoqiang Jua,
- Tusheng Ren *b and
- Chunsheng Hua
Soil thermal conductivity (λ) is strongly influenced by soil water content as well as the arrangement of solid particles in soil. In this study we investigated the influences of soil aggregation on soil thermal conductivity at relatively higher water contents by the thermo-time domain reflectometry (TDR) technique. The relationship between thermal conductivity and water content (θv) was measured for both aggregated (<2 mm) and non-aggregated (<0.1 mm) loam and clay loam soils using two different experimental approaches: continuous vs. non-continuous measurements. The results from the continuous measurement showed that thermal conductivity was significantly higher in the non-aggregated soils than in the aggregated soils at intermediate water contents. This is explained by the formation of intra-aggregate pores in aggregated soils that decreases the contacts and heat flow between aggregates. Alternatively the non-aggregated soils have a relatively uniform pore system that enhances bridging between neighboring particles through pore water, thus improves heat conduction. For the non-aggregated soils, relatively larger bulk density increase during the drying process also contributes to the greater thermal conductivity than that of aggregated soils. The results from the non-continuous approach, however, showed similar thermal conductivity values for the aggregated and non-aggregated soils, which was possibly caused by aggregate reformation in non-aggregated samples during soil mixing and packing.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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