The present paper deals with the physical and morphological studies of soil structure.In view of the fact that the aggregates formed by organic colloids are high both in water stability and porosity,effective on the improvement of soil structure and on the augmentation of soil fertility,and that those formed by clay and other cemented inorganic materials,though high in water.stability,are low in porosity,unable to ameliorate soil structure and to increase soil fertility.The soil fertility,as affected by the content of water stable aggregates,depends,on the whole,upon the conditions in which the aggregates are formed.In the soil of good structure,well developed porosity represented by the augmentation of the total and non-capillary porosity,the porasity of aggregates and the porosity filled with capillary water may improve the physical properties of soils,increase aeration and water percolation and prevent to some extent from water evaporation.