Banca de QUALIFICAÇÃO: LORENA MAUES MORAES

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : LORENA MAUES MORAES
DATE: 30/07/2024
TIME: 13:00
LOCAL: Sala meet.google
TITLE:

Dynamics of carbon and nitrogen stocks and greenhouse gas emissions in soils of the Amazon deforestation arc

KEY WORDS:

Amazon, Carbon stock, Greenhouse gases, Sustainable management, Land use change.  

PAGES: 80
BIG AREA: Ciências Agrárias
AREA: Zootecnia
SUBÁREA: Pastagem e Forragicultura
SPECIALTY: Manejo e Conservação de Pastagens
SUMMARY:

The conversion of native forests into pastures and crops has an impact on the carbon (C) and nitrogen (N) stocks and greenhouse gas (GHG) emissions of soils. In addition, land management and climatic conditions also influence these dynamics, especially in the Amazon. Despite advances in the study of the C and N cycle, there is still a gap in the understanding of how these combined factors affect C and N stocks and GHG emissions in different land uses. The aim of this study was to investigate soil C and N stocks and GHG emissions in different land uses in the Arco do Desmatamento region of the Amazon, in Pará, Brazil, and it is organized into three chapters. Chapter 1 presents a comprehensive literature review on the subject, providing the necessary theoretical basis. Chapter 2 looks at soil C and N stocks in two locations with different climates: São Domingos do Capim (Af) and Paragominas (Aw), analyzing four types of land use: forest, tillage, intensive pasture and extensive pasture, with soil samples collected at eight depths (0-5, 5-10, 10-20, 20-30, 30-40, 40-60, 60-80 and 80-100 cm). Chapter 3 deals with CO₂, CH₄ and N₂O emissions, quantified in São Domingos do Capim (Af), through three experiments with soil incubation to determine the effect of the characteristics of different land uses, N addition (0, 90, 180 and 270 kg of N ha-¹) and temperature elevation (25°C, 30°C, 35°C and 45°C).  Currently, temperature data is still being generated and this stage of the project is ongoing. The results indicate that, in São Domingos do Capim, the forest and the intensive pasture have the highest stocks of C and N in both the surface layer (0-30 cm) and the total depth (0-100 cm), with the intensive pasture standing out with 37.1 ± 8.90 Mg ha-¹ of C and 2.86 ± 0.57 Mg ha-¹ of N in the 0-30 cm layer. In Paragominas, C and N stocks are high in all systems, especially in the intensive and extensive pastures. The extensive pasture has the highest C stock in the surface layer (63.9 ± 5.49 Mg ha-¹), and the intensive and extensive pastures have the highest stocks in the total depth (115.0 ± 10.03 Mg ha-¹). In terms of N, the forest leads with 5.63 ± 1.04 Mg ha-¹ in the 0-30 cm layer and 9.85 ± 1.27 Mg ha-¹ in the 0-100 cm layer. GHG emissions in the Af climate show that forest and intensive pasture have the highest emissions of N₂O and CO₂, while extensive pasture has negative emissions of N₂O and CH₄. The addition of nitrogen significantly increases GHG emissions in all systems, especially intensive grazing. At a dose of 180 kg ha-¹, CO₂ emissions are high in the intensive pasture (1137.65 mg g-¹ of dry soil) and in the forest (772.63 mg g-¹ of dry soil). At the highest dose of 270 kg ha-¹, the forest shows a significant increase in CO₂ emissions (1444.51 mg g-¹ of dry soil), while N₂O and CH₄ emissions decrease in the intensive and extensive pastures. Intensification of land use, as in the case of intensive grazing, increases GHG emissions, while more sustainable management practices can mitigate these emissions by maintaining high stocks of C and N.

COMMITTEE MEMBERS:
Presidente - ***.634.163-** - ANIBAL COUTINHO DO REGO - UFC
Externo à Instituição - RICARDO DE OLIVEIRA BORDONAL
Externo à Instituição - CELSO HENRIQUE LEITE SILVA JUNIOR - INPE
Externo à Instituição - ABMAEL DA SILVA CARDOSO
Externo à Instituição - WILTON LADEIRA DA SILVA - UFG
Externo à Instituição - JOSÉ DE SOUZA OLIVEIRA FILHO
Externo à Instituição - NAUARA MOURA LAGE FILHO - UFPA