Structure of soil and its hygienic value

The Soil consists of firm particles of various size and the form (grains) and free intervals between them a time filled with air. Distinguish soil sandy, sandy, clay, etc. Soil name sandy if, in it contains about 90% of sand and less than 10% of clay, sandy - about 30% of clay, loamy - 50% and clay - more than 50% of clay.

If the soil has large grains and a time, it is called as coarse-grained (sand, supesok). Porosity (the relation of volume of a time to the soil volume, expressed in percentage) such soil is rather insignificant - 25-40% of total amount. The coarse-grained soil easily pronitsaema for air also does not detain water, therefore it dry.

The Fine-grained soil (clay, peat) contains a considerable quantity of a small time. Porosity of clay reaches to 50, peat soil - 84%. Owing to the small size of a time such soil badly passes water and is capable to keep it on the surface.

The Soil is a bad conductor of heat, therefore heating and cooling of blankets of soil is rather slowly transferred deep into. Fluctuation of temperature of soil considerably only on depth of 5 sm, on depth of 0,5-1 m it is absent, and the average temperature of soil here is equal to average temperature of air. On depth of 16-30 m the soil temperature remains to a constant. In process of deepening the temperature increases by each 34,1 m on 1 В°s. The soil temperature depends on a climate, solar radiation, structure, from vegetation presence. So, the sandy soil heats up faster, than clay.

The Big hygienic value has ability of soil to detain mineral and organic substances. The substances which are in water filtered through soil, including microorganisms, will be late in it if their sizes there is more than diameter of interstices of soil (mechanical absorbing ability of soil).

Adsorption by particles of soil of the substances dissolved in soil water is called as physical absorbing ability.

The Substances which are in the dissolved condition in soil waters, enter chemical reaction with the substances which are a part of soil, and form the insoluble products of this reaction which are late in a time of soil (chemical absorbing ability of soil). The substances dissolved in soil water are absorbed by plants, the microorganisms which are in soil (biological absorbing ability).

Thus, the soil possesses the big ability inaktivirovat harmful substances getting to it and pathogenic microorganisms at the expense of physical and chemical processes, microbiological decomposition, absorption by the higher plants and soil fauna, i.e. Actively participates in self-cleaning processes. Thus the big role is played by mechanical structure of soil. So, in coarse-grained soil self-cleaning processes proceed more vigorously owing to bolshego inflow of the oxygen necessary for oxidation of organic substances, containing in soil.