SOIL STRUCTURE CLOSE UP | MARTINS LIBRARY

Only about  50%  of the soil is solid materials, the  remainder is pore spaces, it is in this spaces, that water is stored organism live there, organic  matter and  nutrients accumulate thee, the arrangement of soil  particles gives a porosity of 50%  small pores with  in the aggregates and the large pore (tissures )  between the aggregates are pathways for liquid, gases, roots and organism.  The structure and layout  of the soil both determines how  activities in the soil  happens, the rate at which they happen and  the capability to keep them happening 

The following characteristics are used to help evaluate the ability of any soil to form a well aggregated structure

1.      Porosity:  this is the pore space in the soil between mineral particles and organic matter, filled with either air and  water, the pore space contains and  controls  most functions of the soil, ie storage pores  retains water, while transmission pore enables root growth  and the movement of air and water. 

2.      Soil  particles:  mineral soil particles comes from  rocks and sediments, the coarser materials are usually fragments of the original  materials while the  finer are   usually products of usually products of weathering, the  mineral particles are primary determinants of soil structure

3.       Bonding and aggregation: the   mineral component  of a soil has the primary influence on how soil particles binds together and therefore  what sort of   aggregation results, soil dominated by said tends to  bond weakly , clay soils bonds strongly but different clays gives different bonding strengths.

The strength at which aggregates bonds is impacted  to the  soil by virtue of  

i.                    Cohesive forces between particles

ii.                 Frictional  resistance meet by particles  that are forced to slide over one another