Scale Factors in Soil Science

Methods used in soil science to derive scale factors for soil properties include the dimensional method called similitude analysis which is based on physical characteristics of a soil system and an empirical method called functional normalization which is based on regression analysis. In the past, researchers have assigned physical significance to empirically determined scale factors on the basis of corresponding scale factors derived from similitude analysis. This paper demonstrates that scale factors determined through functional normalization are not always physically equivalent to those determined from similitude analysis. This paper also describes two additional dimensional methods that can be used to derive scale factors for soil properties, namely dimensional and inspectional analysis. Examples of dimensional analysis, inspectional analysis, and functional normalization are presented for a variety of soil science disciplines.