The procedure for evaluating the combinations of soil-forming factors that favor the development of vertic properties in soils

摘要

The procedure of integral qualitative and quantitative evaluation of soil-forming factors and their combinations that favor the development of vertic properties in soils is outlined. The following factors are considered: (1) climate, i.e., the ratio of annual precipitation to evapotranspiration and the value of moisture deficit for the whole year and for the dry season; (2) geornorphic conditions, i.e., the position of a site in relief that dictates the character of surface runoff (the proportion between the input and loss of surface water); and (3) lithology, i.e., the proportion of clay and physical-clay in the fine earth fraction and the content and qualitative composition of smectitic minerals. The integral estimate of a combination of these factors is calculated from the assessments of separate factors and their combinations with the help of special diagrams and tables.