This paper is one part of the study on the essence of soil fertility.It proves again that the characteristics of binding status and the content of various components of soil humic substances and the quantitative distribution of different fractions of microaggregates strongly influence the "physique" and the "pedon structure" of soil.The constituent characteristics and functioning mechanism of fundamental substances of fertility in red earth are related to a certain eztent to the higher content of free ferric oxides in soil and their different distribution in various fractions of microaggregates.