الوصف
Soil can be defined as the space time continuum forming the upper part of the earth's crust. It is a natural body comprised of solid, liquid and gases that occur on the land surface. Joffe (1949) defined soil as a natural body differentiated into horizons of mineral and organic constituents usually unconsolidated of variable depth, which differs from the parent material below in morphology, physical properties and constitution, chemical properties and composition, and biological characteristics.