Banca de DEFESA: RAFAEL SILVA GUEDES
Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.DISCENTE: RAFAEL SILVA GUEDES
DATA: 22/07/2016
HORA: 09:00
LOCAL: Auditório do programa de pós-graduação
TÍTULO:
Phosphorus in Amazonian soils: kinetic, losses risk and chemical fractions
PALAVRAS-CHAVES:
Phosphorus kinetics, hysteresis, degree of phosphorus saturation, P fractionation, SEM-EDS
PÁGINAS: 91
GRANDE ÁREA: Ciências Agrárias
ÁREA: Agronomia
SUBÁREA: Ciência do Solo
ESPECIALIDADE: Manejo e Conservação do Solo
RESUMO:
Amazonian soils generally have low levels of available phosphorus (P), mainly due to oxidic and kaolinitic mineralogy, typical of highly weathered soils. Because of that, adsorption reactions that cause P unavailability are considered a serious impediment to the proper management of P and may lead to excessive application of nutrients, causing environmental damage. On the other hand, soils rich in phosphorus, such as Terra Preta do Indio (AT) can provide important informations to help improve P management in Amazonia region. The aim was to evaluate adsorption and desorption kinetics, degree of saturation and distribution of P forms in different soils of Amazonia region. For this, four soils located in Pará state were selected for evaluation of kinetic parameters related to adsorption and desorption and irreversibility of adsorption (hysteresis) carried out in stirred flow chamber. Eleven soils located in the state of Pará were selected also, with which were carried out adsorption experiments by batch method, in addition to assessment the degree of phosphorus saturation (DPS). Moreover, P fractions distribution was analyzed in AT by sequential chemical extraction, which was supplemented by electron microscopy analysis with energy dispersive spectrum. Was observed that in FR-1(Xanthic Ferralsol-1), FR-2 (Xanthic Ferralsol-2) and FR-3 (Rhodic Ferralsol), approximately half of adsorption occurred by rapid sites (F ranging from 0.45 to 0.55), while in AT (Hortic Anthrosol) adsorption was lower (qmax = 48.95 mg kg-1) and occurred more slowly (F=0.33). In FR-2 and FR-3, between 71 and 72% of P adsorbed was not desorbed, while in AT, only 11% of P was adsorbed irreversibly. DPS was higher in the soil AT also showing larger values of available and soluble P, while lower saturation values were observed in FR2, FR4, AC2 (Haplic Acrisol 2) and GL (Eutric Gleysol) (< 5%). The residual P fractions were higher in non-anthropogenic soils while in AT the labile and moderately labile fractions showed higher values, moreover was possible to confirm the relationship of these fractions with inorganic colloids and organic matter by electron microscopy with EDS.
MEMBROS DA BANCA:
Presidente - 6388356 - ANTONIO RODRIGUES FERNANDES
Externo à Instituição - DANIEL ARENAS LAGO - NENHUMA
Externo à Instituição - EMMA FERNÁNDEZ COVELO - NENHUMA
Externo ao Programa - 2874082 - GILSON SERGIO BASTOS DE MATOS
Externo ao Programa - 260.577.942-49 - JOAO ROBERTO ROSA E SILVA - UFRA