removed from the profile. The soils remain neutral or slightly alka- 

 line. The bulk of the water returns to the atmosphere by evaporation 

 and transpiration, the latter mode predominating. Contrary to many 

 beliefs, this water regime will not produce alkali or saline soils. As is 

 discussed above, special ground-water conditions are necessary for 

 their development. 



Under high rainfall, water percolates through the soil profile and 

 finally finds its way into rivers, lakes, and oceans. Soluble and dis- 

 persible substances are continuously removed from the soil. Soils in 

 humid regions tend to become leached and acid. 



With respect to the climate function, the complex factor cl may be 

 conveniently split into a moisture variable m, and a temperature 

 variable T, both being treated, mathematically, as varying independ- 

 ently of each other. Accordingly, one may speak of soil property- 

 moisture functions and soil property-temperature functions: 



S = f(m) T , ,r,p,t S = J(T) mi0 ,T,p,t 



Good illustrations of s-m functions have been reported from the cen- 

 tral portion of the Great Plains area, especially the states of Kansas 

 and Nebraska. Here one may select localities having nearly identical 

 mean annual temperatures but considerable variations in mean annual 

 rainfall. Vegetation consists of grass communities; the parent mate- 

 rial is loess and related wind-blown materials. By selecting samples 

 from level ridges, topography also may be kept constant. 



Figure 6, based on analyses by Alway (Jenny, 1941), portrays the 

 variation of the calcium content of virgin soil profiles. As one pro- 



