%0 Journal Article
%T Subsurface Lateral Flow in Texture-Contrast (Duplex) Soils and Catchments with Shallow Bedrock
%A Marcus A. Hardie
%A Richard B. Doyle
%A William E. Cotching
%A Shaun Lisson
%J Applied and Environmental Soil Science
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/861358
%X Development-perched watertables and subsurface lateral flows in texture-contrast soils (duplex) are commonly believed to occur as a consequence of the hydraulic discontinuity between the A and B soil horizons. However, in catchments containing shallow bedrock, subsurface lateral flows result from a combination of preferential flow from the soil surface to the soil¡ªbedrock interface, undulations in the bedrock topography, lateral flow through macropore networks at the soil¡ªbedrock interface, and the influence of antecedent soil moisture on macropore connectivity. Review of literature indicates that some of these processes may also be involved in the development of subsurface lateral flow in texture contrast soils. However, the extent to which these mechanisms can be applied to texture contrast soils requires further field studies. Improved process understanding is required for modelling subsurface lateral flows in order to improve the management of waterlogging, drainage, salinity, and offsite agrochemicals movement. 1. Introduction Texture-contrast soils (duplex) cover approximately 20% of the Australian land mass [1] or 2.33£¿million£¿km2 [2]. According to Chittleborough et al. [3] texture-contrast soils occur on around 80% of agricultural regions in southern Australia and around 60% of the agricultural regions of south-western Western Australia [4]. The term ¡°texture-contrast soil¡± has not been explicitly defined in a formal soil classification system. The term ¡°texture-contrast¡± was first used in the Great Soil Group [5] and Handbook of Australian Soils [6] in reference to the solonetz, solodized solenetz, and the soloths, which all have a marked texture-contrast between the upper and lower horizons. Northcote [7] described the texture-contrast soils as ¡°duplex¡± in which the subsoil (B horizon) texture is at least one and a half texture groups finer than the surface soil (A Horizon), and horizon boundaries are clear to sharp. The Australian Soil Classification [8] identified three soil orders: Sodosols, Kurosols, and Chromosols, which have a clear or abrupt textural B horizons. Although the term ¡°duplex¡± has only been used in Australia, soils with contrasting texture between soil horizons are found in other parts of the world [9]. In ¡°Soil Taxonomy¡± [10], soils showing characteristics most like those of the duplex soils are classified with the formative element ¡°pale¡± meaning to show excessive development. This includes 15 Great Groups in 3 orders: the Mollisols, Ultisols, and Alfisols. In the FAO-UNESCO World Soil Map (FAO-UNESCO 1987), duplex soils
%U http://www.hindawi.com/journals/aess/2012/861358/