Clarification for a soils category

Spatial differentiation of soil cover in Poland according to a susceptibility of different categories of soil to the drought - a very light soil (very susceptible), light soil (susceptible), medium-heavy soil (medium susceptible), heavy soil (less susceptible).

I - very light soil, granulometric group: sand
II - light soil, granulometric group: loamy sand
III - medium-heavy soil, granulometric group: sandy loam
IV - heavy soil, granulometric group: sandy clay loam
clay loam
silt loam

The soil categories are established in accordance to the granulometric composition of the soil profile, according to the above-allocated criteria based on digital soil - agricultural maps demonstrating spatial diversity of soil habitats and their water capacity.