The formation of stable soil structure

THE FORMATION OF A STABLE SOIL STRUCTURE BY THE AGGREGATION OF SOIL PARTICLES 

Aggregation of soils is necessary to obtain optimum growth conditions for plants, and to enable soil cultivation to be carried out. Aggregation also helps to prevent most forms of soil erosion and reduce soil crusting. 

In addition aggregation is very important in allowing free movement of water and air in soil. 

There are three main lines of evidence to support the involvement of polysaccharide in soil aggregation firstly, the strong adhesive qualities possessed by many polysaccharides secondly, the effect of the addition of polysaccharide to soil particles on the formation of stable synthetic aggregates, and thirdly, the effect of periodate and tetraborate, which remove carbohydrate, in disrupting natural aggregates. 

Over a long period polysaccharides have been used as gums, for example modified-starch, wallpaper pastes. The stickiness of a polysaccharide is governed by the size and shape of the molecule, the most effective being 

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