caliche

caliche

chilensalpietari puhekieltä A crude form of sodium nitrate from South America; used as a fertilizer.
A layer of hard clay subsoil or sedimentary rock; hardpan.
1929, US Bureau of Chemistry and Soils, Soil Survey of Potter County, Texas, http://books.google.com.au/books?id=iuzwAAAAMAAJ&pg=PA44&dq=%22caliche%22&hl=en&sa=X&ei=_DETU7_7JIehkAWE5oDQCw&redir_esc=yv=onepage&q=%22caliche%22&f=false page 44,

According to local well drillers, in wells drilled on the high plains a few hundred feet back from the caliche escarpment or in other locations on the high plains in this area no hard caliche or white layer, such as would characterize a soft layer of high lime-carbonate content, is generally reached at a depth corresponding to the elevation of the caliche escarpment.

Having a layer of caliche at depths of 16 inches and less really puts a damper on the garden site. The caliche does not allow roots to penetrate it (tree roots often take 10 years to break through a caliche layer) nor does this mineral allow water to drain.

Caliche in various forms, namely powdery, nodule, tube, fracture-infill, laminar crust, hard laminated crust (hardpan) and pisolitic crust, is widespread in the Mersin area in southern Turkey (Eren et al., 2008; Kadir and Eren, 2008).