Banca de DEFESA: SAMUEL DE ABREU LOPES

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : SAMUEL DE ABREU LOPES
DATE: 10/09/2026
TIME: 14:00
LOCAL: videoconferência
TITLE:

Development of a biological soil conditioner for fragile soils based on humified organic matter and Basidiomycete fungi

KEY WORDS:

biomineralization; fragile soils; Macrocybe; oxalate–carbonate pathway; regenerative agriculture; vermicompost

PAGES: 60
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUBÁREA: Ciência do Solo
SUMMARY:

The restoration of fragile soils in tropical ecosystems requires inputs capable of integrating stabilized organic matter, effective biological activity, and interactions at the organomineral interface. This study investigated the colonization of different vermicompost preparations by Macrocybe sp. and the resulting transformations across three matrices: vermiculite moistened with a malt extract solution, serving as a mineral control with readily available carbon; autoclaved vermicompost (VCA); and non-autoclaved vermicompost (VCS). The samples were evaluated before colonization and after 35 and 60 days, considering the following parameters: pH, cation exchange capacity (CEC), mass loss on ignition, elemental analysis of carbon, hydrogen, and nitrogen (CHN), inductively coupled plasma optical emission spectrometry (ICP-OES), Fourier-transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR) associated with principal component analysis (PCA), X-ray diffraction (XRD), and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS). The basidiomycete Macrocybe sp. effectively colonized all three matrices, forming filamentous networks that interconnected mineral and organomineral particles. The pH decreased during the first 35 days in all treatments; however, between 35 and 60 days, VCS exhibited a pH increase from 6.560 to 6.807, whereas the control and VCA maintained an acidification trend. During the same interval, the inorganic carbon fraction in VCS increased from 8.79% to 9.73%. SEM-EDS revealed tabular, prismatic, radiating, and spheroidal crystals, as well as nonhyphal bodies in VCS, predominantly composed of carbon, calcium, and oxygen, with phosphorus detected less frequently. Although these morphotypes are consistent with calcium oxalates, carbonates, and/or phosphates, their identity cannot be established solely from morphology and requires additional confirmatory analyses. The convergence of fungal colonization, late-stage pH recovery, a descriptive increase in the inorganic fraction, and calcium availability supports the hypothesis that fungal oxalogenesis and microbial oxalotrophy acted jointly, particularly in the non-autoclaved treatment, which retained the native vermicompost microbiota. These findings indicate potential for developing a biological soil conditioner and establishing a circular pathway for the valorization of mycelium-colonized substrate, based on the inherent properties of vermicompost and basidiomycete fungi. However, agronomic trials, identification of the microbial communities involved, mineralogical confirmation, and a comprehensive carbon mass balance are still required.

COMMITTEE MEMBERS:
Presidente - 1399485 - ANDRES CALDERIN GARCIA
Interno - 387406 - RICARDO LUIZ LOURO BERBARA
Externo à Instituição - SAEL SÁNCHEZ ELÍAS - UFRRJ