Banca de DEFESA: MELANIA MERLO ZIVIANI

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : MELANIA MERLO ZIVIANI
DATA : 27/02/2020
HORA: 13:30
LOCAL: Departamento de Solos
TÍTULO:

Stocks and Stabilization Mechanisms of C and N in Urucu Soils, Central Amazon Region.

PALAVRAS-CHAVES:

Physical fractionation; C/N ratio; soil organic matter decomposition

PÁGINAS: 53
GRANDE ÁREA: Ciências Agrárias
ÁREA: Agronomia
SUBÁREA: Ciência do Solo
ESPECIALIDADE: Química do Solo
RESUMO:

The stabilization of carbon in soils is governed by the following mechanisms: recalcitrance of organic material, physical protection that occurs during the formation of aggregates and chemical protection that is related to the formation of organo-mineral complexes. The general objective of the work was to evaluate the C and N stock in soils in the Urucu region, Central Amazonia. The objective of the work is also to contribute to an understanding of the relationship between the relief factor (represented by soil drainage) and vegetation in C and N reserves in soils in this region, as well as to elucidate the main mechanisms responsible for carbon stabilization in these soils. The stocks of C and N were calculated and the chemical and physical attributes of thirty-five soil profiles of the region of Urucu, Central Amazonia were evaluated. Physical fractionation of organic matter was carried out in ten soil profiles representative of the region, under different drainage and vegetation conditions. Carbon stocks ranged from 33.0 to 230.3 Mg ha-1 and N stocks ranged from 13.0 to 44.2 Mg ha-1. The factors responsible for the accumulation of organic matter in soils were relief (influencing drainage) and vegetation. The contribution of MOS, measured by the entry of light fraction, was distinct in the three positions of the relief (on dry land, terraces and fluvial plains). In places of good drainage (terra firma) the general averages of FLL and FLI were 141.9 g kg-1 of soil and 22.0 g kg-1 of soil, respectively. In places of poor drainage (fluvial plains) the average FLL and FLI observed were 136.4 g kg-1 of soil, 34.8 g kg-1 of soil, respectively. And in terraces (imperfect drainage) the highest averages of 827.4 g kg-1 of FLL soil and 55.8 g kg-1 of FLI soil were observed. These contributions are directly related to the factors that influence the permanence of organic material in the soil, such as relief and vegetation type. The levels of clay and light fractions of organic matter had a high relationship with the stocks of C and N. On the contrary, the contents of sand and silt and the ratio C / N showed an inverse relationship with the stocks of C and N. By analyzing the dendrogram, soil classes were grouped according to drainage (well, imperfectly and poorly drained). The highest contents of C and N stocks were observed in imperfectly drained soils, followed by well drained soils and lastly in poorly drained soils.

MEMBROS DA BANCA:
Presidente - 1740899 - ERIKA FLAVIA MACHADO PINHEIRO
Interno - 1060711 - MARCOS GERVASIO PEREIRA
Externo à Instituição - DAVID VILAS BOAS DE CAMPOS - EMBRAPA