ABSTRACT
Soil is defined as the unconsolidated natural material on the surface of the earth that has been subjected to various environmental factors. The main function of soil as a medium for plant growth is to provide mechanical support for the plant and to cover plant requirements concerning heat, and air. The main aspect of soil physics for plant productivity is to preserve suitable proportions between solid, liquid, and gaseous phases. These proportions are found to be optimal only in some soils and when climatic conditions and human activity are proper. The solid phase of soil consists of discrete units, called elementary particles or granules. These particles may vary widely in size, shape, and composition. Between soil particles arranged singly or in aggregates, there is a system of pore space on which plant roots, microorganisms, and soil animals depend for the storage and movement of water and air. The spatial arrangement of the solid particles and voids is called soil fabric.
