The Brazilian Soil Classification System - Soil Classification - page 136

Figure 11.4 A map of Brazil showing the main distribution of Alissolos.

upper boundary of the B horizon or 50 cm of the surface. They lack horizon diagnostic for Plintossolos
and Gleissolos, respectively.
This class includes mainly those soils that have been previously identiÝed as Rubrozem,
Podz–lico Bruno-Acinzentado Distr–Ýco or ælico, Podz–lico Vermelho-Amarelo Distr–Ýco, or
ælico Ta and a few Podz–licos Vermelho-Amarelos Distr–Ýcos or ælicos Tb (with clay activity
equal to or more than 20 cmol /kg of clay).

The geographical distribution of this soil class secluded from the 1:5,000,000 scale of the
Brazilian soil map is shown in Figure 11.4. It comprises 374,525 km

c

2

corresponding to 4.4% of

the country.

Soils with a planic B horizon immediately below an A or E horizon and abrupt
textural change; soils having permeability restrictions and evidence of reduction processes with or
without mottles of iron segregation. They lack a spodic B horizon.
This class includes mainly those soils that have been previously identiÝed as Planossolos,
Solonetz-Solodizado, and Hidrom–rÝcos Cinzentos with abrupt textural change.
The geographical distribution of this soil class secluded from the 1:5,000,000 scale of the
Brazilian soil map is shown in Figure 11.5. It comprises 153,214 km

PlanossolosÐ

2

corresponding to 1.8% of

the country.

Grouping of soils with gleyzation characteristics within 50 cm of the surface and
usually saturated permanently or seasonally by groundwater. Lacking diagnostic characteristics of
Vertissolos, Espodossolos, Planossolos, Plintossolos, or Organossolos.
This class includes mainly those soils that have been previously identiÝed as Glei Pouco
Hmico, Glei Hmico, Hidrom–rÝco Cinzento without abrupt textural change, Glei Tiom–rÝco,
and Solonchak with gley horizon.
The geographical distribution of this soil class secluded from the 1:5,000,000 scale of the
Brazilian soil map is shown in Figure 11.6. It comprises 323,453 km

GleissolosÐ

2

corresponding to 3.8% of

the country.

Clayey soils showing an advanced development of pedological ferralitization pro-
cess along with formation of a kaolinitic-oxidic colloid. They have a nitic B horizon with CEC
less than 27cmol

NitossolosÐ

/kg of clay at least within the upper 50 cm of the nitic B horizon, and show
gradual to diffuse horizon boundaries between A and B horizons. They have moderate to strong

c