Caracterização de solos, concreções e nódulos ferruginosos em uma topossequência na Chapada do Apodi - CE.

Abstract

The soils of the Apodi Plateau - EC express a great potential for use in irrigated agriculture. Fertile soil are compared to other soi l from Brazil, and have flat terrain feature of this degree of drainage good to moderate. However, there is some interest from researchers in the field of Soil Science, as its genesis and the p resence of nodules in these soils. Aiming to increase the database is necessary to make a chemic al and mineralogical characterization of soils and nodules found in this environment. Five p rofiles (P1, P2, P3, P4 and P5) found in a soil toposequence developed from calcareous Jandaír a were studied. Was used for chemical analyzes as full attack, sulfuric acid, and DCB-ray diffraction X - to obtain data to make it possible to establish relationships for understandi ng the genesis of soils and nodules. The soils generally have uniform levels of iron and titanium, is not noticed big differences between horizons and profiles. However, the differences, P5 differ from those of other profiles, which is of greater depth, more iron and titanium, repres enting a greater degree of weathering expressed by the lower ratio between the contents o f silicon and aluminum (Ki). The concentration of titanium is present in all profile s uniform evidence indicating that these soils were formed in situ. The main minerals found in soil are kaolinite and muscovite - illite. The nodules had high levels of iron, however, there wer e no inverse relationship between the iron content and size of concretions. The titanium conte nt in soil and concretions when summed and compared to profiles showed similar chemically, evidenced the formation of concretions in situ . The main minerals found in nodules and concretion s were kaolinite, quartz, goethite, hematite, anatase and rutile.