Brine Concentrated solution of salts. Impermeable layer Layer of clay below ground surface that can impede downward percolation of water. Leaching The removal of salts and trace elements from soil by the downward percolation of water. Salts A class of compounds that includes common table salt, sodium chloride, as well as salts of concern in irrigated agriculture, e.g. the various carbonates, bicarbonates, sulfates, phosphates and chlorides of sodium, calcium, potassium and magnesium. An impermeable clay layer causes water to accumulate just beneath the land surface.
Tile drains remove the water from the root zone to a stream, drainage ditch, or evaporation pond.
Tile drains A network of pipes, formerly made of ceramic tile but now usually plastic, buried in fields below the root zone of plants. The drains are designed to collect excess water and carry it by gravity flow to one point where it can be pumped out to a canal stream or evaporation pond. Trace elements Members of the set of 92 naturally occurring elements found in low concentrations, usually less than one part per million, in rocks, soil and water. Published by the San Francisco Estuary Project in August, 1992.