Evaluation of soil compaction using hydrodynamic water content variation: Comparison between compacted and non-compacted soil

A simple method, allowing the evaluation of the effect of compaction on soil structure is presented. The method is based on soil moisture measurements via Time Domain Reflectrometry (TDR). The hydrodynamic variation of soil moisture has indicated two types of compaction: 1) Compaction by load traffic caused a reduction of structure in the top 0.10 m layer. Consequently, no water flow occurred downward. The TDR measurements suggest a poor continuity of pores between top and subsoil. This observation has been confirmed by the measurements of bulk density, macroporosity, and dye infiltration experiments. 2) Compaction by intensive stock trample in which micropores are reduced. Macropores on the contrary are well developed, and resistant to the vertical compression in compacted soil and therefore dominated infiltration. Moreover, in reconstructed soils, micropores carried most of the flow, as demonstrated by the modeling results. Macropores are not yet developed in these young soils.