It is essential to make clear a system analysing material transport in soils, in order to increase food production and to conserve the natural environment. This report describes a quantitative concept of physical,chemical and biological phenomena making up a system of material transport in soils, such as pore structure in soil, absorption of ions to soil particles, capture of solid particles in pores,decomposition of organic matter, and dissolution and precipitation of chemical materials in soil water. In conclusion,it is stated in detail that prediction of material transport in soils will be successful after such actions are quantitatively described by using mathermatical equations and after they are combined with material transport equations.