Banca de DEFESA: SHIRLEI ALMEIDA ASSUNÇÃO
Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.DISCENTE : SHIRLEI ALMEIDA ASSUNÇÃO
DATA : 18/02/2020
HORA: 13:30
LOCAL: Instituto de Agronomia
TÍTULO:
Chemical and Functional Characterization of Soil Organic Matter and Fractions and Phosphorus Forms in Different Oxidation Soil Management Systems
PALAVRAS-CHAVES:
Soil organic matter, humic substances, carbon balance, tropical climate, weathering
PÁGINAS: 86
GRANDE ÁREA: Ciências Agrárias
ÁREA: Agronomia
SUBÁREA: Ciência do Solo
ESPECIALIDADE: Manejo e Conservação do Solo
RESUMO:
Due to its importance in tropical soils, organic matter becomes an important indicator of soil quality. In addition to having a direct influence on soil phosphorus (P) availability, mainly in oxide soils. The objective of this study was to evaluate the changes in the chemical and functional structure of soil organic matter (SOM) and to demonstrate how the fractions and forms of phosphorus in the soil behave in different management systems in oxidized soil. Three managed areas and one reference area (native forest) were evaluated. The three areas managed include: no-tillage system (NT), conventional tillage system (T) and permanent pasture (PP). Total organic carbon (TOC), potassium permanganate oxidizable carbon (POX), carbon (C) and nitrogen (N) stocks, chemical and densimetric SOM fractions, 13C natural abundance, and spectroscopic characterization were quantified. using 13C NMR in humic acid (HA), remaining phosphorus, available phosphorus, total phosphorus and 31P NMR in HA, in addition to the forms of iron and aluminum oxalate and dithionite. The results showed that the area with forest (F) accumulates high amount of organic C in surface (chemical, densimetric fractions), favoring the formation of predominantly aliphatic HA. On the other hand, in the NT, despite the constant contribution of biomass to the soil, there is low incorporation of aliphatic structures in HA, indicating a higher carbon mineralization. In the PP system, the formation of HA similar to those observed in the area of F was verified. In the T, it was found less incorporation of total organic carbon (TOC), C and N stock and the formation of HA of different compositions in comparison. with the other forms of management. With these results, it is possible to state that the poorly managed and more stabilized systems in tropical climate populate the formation of HA with compositional and structural similarity independent of the carbon nature (C3 and C4). Conversely, in areas managed with or without greater carbon input, structurally different HA are observed when compared with the PP and F areas. This study opens new research possibilities where it is necessary to model experiments that provide specific answers on the relationship. between the contribution of C, the management and the formation of humic substances. Regarding the availability of P, in the area of PP management, lower crystalline forms of Fe were observed, possibly due to the higher humidity present in this area due to the soil cover. Higher levels of available P were quantified in the management area SPD and PP in all evaluated layers and higher levels of Rem-P and total P in the 0-0.05 m layers, indicating that soil non-revolving and MOS accumulation are essential. for the maintenance of P. There was no relationship between the availability of P and the soil Fe. 31P CP MAS NMR spectra HA showed predominance of organic forms of P. The management with PP favored the accumulation of P-diester. In the area of F the incorporation of sugar-like nucleotides is observed and in the management of T and NT the P-monoester structures accumulated in greater quantity. The higher cultivation intensity seems to favor the more recalcitrant organic P structures.
MEMBROS DA BANCA:
Externo à Instituição - ARCÂNGELO LOSS - UFSC
Interno - 681.282.827-00 - BRUNO JOSÉ RODRIGUES ALVES - EMBRAPA
Externo à Instituição - DAVID VILAS BOAS DE CAMPOS - EMBRAPA
Externo à Instituição - JOSE LUIZ RODRIGUES TORRES
Presidente - 1060711 - MARCOS GERVASIO PEREIRA