zero point of charge Refer to point of zero net charge.

zero tillage Refer to tillage, no-tillage (zero-tillage) system.

zeta potential Refer to electrokinetic potential.

zibar A small, low-relief sand dune that lacks discernible slip faces and commonly occurs on sand sheets, in interdune areas, or in corridors between larger dunes. Zibar spacing can range from 50 to 400 m with local relief <10 m. Unlike coppice dunes, zibars are not related to deposition around vegetation. Generally dominated by coarser sands (Schoeneberger and Wysocki, personal communication, 2013; Jackson, 1997; Lancaster, 1995). Compare dune, coppice dune.

zonal soil (a) A soil characteristic of a large area or zone. (b) (obsolete; not used in the current U.S. soil taxonomy) One of three primary divisions (orders) in soil classification (e.g., “normal soils”) formerly used in the United States.(Baldwin et al., 1938).

zone subsoiling Refer to tillage, zone subsoiling.

zone tillage Refer to tillage, zone tillage.

zymogenous flora So-called opportunistic organisms found in soils in large numbers immediately following addition of a readily decomposable organic substrate. Synonym with copiotrophs.