Banca de DEFESA: NARA NUBIA DE LIMA CRUZ

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : NARA NUBIA DE LIMA CRUZ
DATE: 17/12/2021
TIME: 08:00
LOCAL: Defesa remota pelo Google Meet
TITLE:

ABSTRACT

KEY WORDS:

Duricrust, Duripan Fragipan, Hardened soils.

PAGES: 95
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUBÁREA: Ciência do Solo
SUMMARY:

The cementation process occurs in different classes of soils, from Argissolos to Spodosols,
mainly expressed in the form of fragipan and duripan. Studies on the Pedogenesis of these
horizons highlight different theories regarding their formation, however, a precise explanation
of the actions of these cementing agents in the development of these horizons is needed. Due
to its interference in the movement and storage of water in the soil, directly affecting the
development of plants by preventing root growth and nutrient absorption, therefore,
knowledge of the genesis of these soils is crucial for use planning. Thus, the following work
aimed to: Evaluate changes in soil horizons that lead to cementation formation, and the main
cementing agents involved, in order to understand its genesis and evolution over time, in
northeastern Brazil. The work was carried out in the municipality of Mataraca – PB, with
three profiles with different scales of cementation along the landscape, classified as Argissolo
Amarelo, Espodossolo Ferri-humilúvico, Espodossolo Humilúvico. In the field,
morphological descriptions were carried out and samples were collected for processing in the
laboratory, where physical, chemical, mineralogical attributes and organic analyzes were
evaluated, and subsequently data processing was carried out for principal component analysis
- PCA and correlations that were applied to the results obtained. The physical and chemical
attributes reflect the sediments that formed these soils, coming from the barrier formation, that
is, these soils developed on sediments that have already been weathered, thus justifying the
predominant sandy texture in most of the horizons, as well as the poor chemistry in nutrients,
acidity and the high aluminum saturation found. Among the selective extractions, aluminum
was the element that stood out in relation to iron and silicon, with aluminum bound to organic
forms extracted with sodium pyrophosphate presenting the greatest selectivity in relation to
the others. For mineralogical analysis of the clay fraction, both for X-ray diffraction and for
differential thermal analysis, they presented the same composition with quartz as the
dominant primary mineral, followed by the presence of kaolinite, anatase, and feldspar-k and
gibsite. The composition of the organic matter showed a predominance of Humina and fulvic
acids, as well as in the fractionation of oxidizable carbon, the forms that present greater
recalcitrance stood out in relation to the more labile forms. For the structural composition of
carbon, the cemented horizons are more enriched when compared to those without
cementation, as well as differences in their structural composition. With the application of
statistical analysis to PCA, it was possible to explain 68% of the total variability of the data,
where PCA, grouping cemented versus uncemented horizons, and their relevant variables.
Thus, it was possible to conclude that the cementing element was aluminum, with the
podzolization process developing concomitantly with the cementation.

BANKING MEMBERS:
Externo à Instituição - TIAGO OSORIO FERREIRA - USP
Externo à Instituição - JOSE COELHO DE ARAUJO FILHO
Externa à Instituição - CAROLINE DELPUPO - IFMG
Externa à Instituição - JANE KELLY SILVA ARAUJO
Presidente - 1538852 - VALDOMIRO SEVERINO DE SOUZA JUNIOR