SOIL TEXTURE AND STRUCTURE

SOIL TEXTURE AND STRUCTURE
Soil texture refers to particle sizes composing the soil. Particles are classified as various grades of gravel, sand (2­0.2 mm), silt (0.2-0.0002 mm) and clay (less than 0.002 mm), in decreasing order of size. Most soils contain some of each category. A well-balanced mixture (i.e., a loam soil) gives the optimum conditions of water holding, temperature and supply of plant nutrients. It is often possible to identify soil texture by its 'feel'; e.g., sand feels gritty to touch. Texture results principally from the mineral composition of the parent material.

'Soil structure refers to the way in which soil grains are grouped together into larger pieces held together by colloids. Soil structure influences the rate at which water is absorbed by the soil, the susceptibility of soil to erosion and the ease of soil cultivation. Soil structure may be: (a) blocky or nutlike, where the lumps or pods of soil have irregular pieces with sharp comers and edges; (b) crumb or granular structure, with more or less spherical pieces; (c) columnar or prismatic structure made up of- vertical columns or prisms; (d) platy structure, consisting of plates of flat pieces, in a horizontal position.