page_title: Leaching model (soil)
section_title: Leaching efficiency
hierarchical_section_title: Leaching model (soil) / Leaching efficiency
caption_attribution_description: Explanation of leaching efficiency of the soil
context_page_description: A leaching model is a hydrological model by which the leaching with irrigation water of dissolved substances, notably salt, in the soil is described depending on the hydrological regime and the soil's properties.
  The model may describe the process in time and as a function of amount of water applied.
  Leaching is often done to reclaim saline soil or to conserve a favorable salt content of the soil of irrigated land as all irrigation water contains salts.
context_section_description: Owing to irregular distribution of salt in the soil or to irregularity of the soil structure (figure 2), the leaching efficiency (EL) can be different from unity.
  Soils with a low leaching efficiency are difficult to reclaim. In the Tagus delta, Portugal, the leaching efficiency of the dense clay soil was found as low as 0.10 to 0.15. The soil could not be developed for intensive agriculture and was used for rearing of bulls in coarse natural pasture.
  The clay soil in the Nile delta, Egypt, on the other hand has a much better leaching efficiency of 0.7 to 0.8. In figure 3, leaching curves are shown for different leaching efficiencies, as assumed in the leaching model SaltMod   with data from the Mashtul pilot area. The observed values of soil salinity correspond best to a leaching efficiency of about 0.75. The figure illustrates the calibration process of leaching efficiency, which parameter is difficult to measure directly.
caption: Figure 2. Principle of leaching efficiency
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