Banca de DEFESA: LEONARDO CRISTIANO DA SILVA FREITAS

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : LEONARDO CRISTIANO DA SILVA FREITAS
DATE: 27/02/2025
TIME: 14:00
LOCAL: Remota (Plataforma Google Meet)
TITLE:

Characterization of saprolites below shallow solums derived from crystalline rocks in the semiarid region of Pernambuco

 

KEY WORDS:

Soil chemistry, Soil physics, Soil mineralogy, Soil morphology.

PAGES: 107
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUBÁREA: Ciência do Solo
SUMMARY:

Shallow solums, solums with depths of less than 50 cm, occupy vast areas of the semiarid region of Pernambuco. In the current context of climate change, the search for sustainable land use strategies that meet the demands of small farmers in semiarid regions has gained prominence. Among the components of semiarid landscapes, shallow solums stand out; however, their agricultural potential is often underestimated due to their limited depth, and they are considered unsuitable for agriculture by many public and private funding agencies. Although different regolith characteristics are recognized as contributing to the agricultural potential of soils, the
influence of the saprolite underlying shallow solums is still poorly understood. Thus, this study aims to demonstrate that saprolite derived from crystalline rocks, often underestimated, has morphological, mineralogical, physical and chemical attributes that complement the overlying shallow solums. For this purpose, samples of shallow soils and respective saprolites from different crystalline rocks were collected in three profiles located in the municipalities of Gravatá, Serra Talhada, and Floresta, aiming to encompass different semiarid contexts. In the field, the morphological description and classification of the solum-saprolite set were initially carried out. Then, deformed and undisturbed samples were collected for physical, chemical, and mineralogical analyses. The samples were subjected to physical, chemical, and mineralogical analyses in laboratories, following Embrapa's standard methodologies. The results showed that the saprolites have important characteristics that contribute to the overlying shallow solums. The chemical attributes revealed high levels of exchangeable bases in the saprolite horizons with a potential CEC ranging from 98.8 mmolc kg-1 in the Litholic Neosol to 452.6 mmolc kg-1 in the chromic Luvisol, in addition to low Al3+ levels, low percentage of exchangeable sodium (PST) and high phosphorus values, especially in the Haplic Planosol, reaching 387 mg kg-1. These characteristics indicate that saprolites can improve the nutrient retention capacity and the availability of essential elements for crop development. The presence of roots in the saprolite horizons indicates the importance of these horizons below shallow solums. Mineralogy demonstrated that saprolites have 2:1 clays such as smectites and vermiculites and primary minerals such as biotite and feldspars, which function as a nutrient reserve. These attributes are particularly relevant for optimizing the use of these soils in the semiarid region, which are often managed by peasants and small family farmers, thus expanding the possibilities for agricultural use in the drought polygon. Furthermore, knowledge of the agronomic characteristics of saprolite below shallow solums contributes to addressing climate change. This research contributes to the understanding of the attributes of shallow solums and their respective saprolites in the semiarid context, in addition to benefiting small farmers by providing them with a scientific basis for optimizing agriculture in the region, and will have significant impacts on environmental awareness and the promotion of sustainable agricultural practices.

 

COMMITTEE MEMBERS:
Externo à Instituição - ANTONIO CARLOS DE AZEVEDO - USP
Presidente - JEAN CHEYSON BARROS DOS SANTOS
Externo à Instituição - LUCAS RESMINI SARTOR - UFS