Banca de DEFESA: JOHNNY JEAN

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE: JOHNNY JEAN
DATA: 28/08/2026
HORA: 08:00
LOCAL: DCS02
TÍTULO:

COFFEE HUSK BIOCHAR COMBINED WITH COVER CROPS AS AN INTEGRATED REHABILITATION STRATEGY FOR A DEGRADED TROPICAL DYSTRIC CAMBISOL: PHYSICAL, CHEMICAL, AND BIOLOGICAL SOIL RESPONSES ACROSS CONSECUTIVE CROPPING CYCLES

PALAVRAS-CHAVES:

Edaphic and vegetative practices, environmental and agricultural sustainability, regenerative agriculture, soil quality and health.

PÁGINAS: 80
GRANDE ÁREA: Ciências Agrárias
ÁREA: Agronomia
SUBÁREA: Ciência do Solo
ESPECIALIDADE: Manejo e Conservação do Solo
RESUMO:

Soil degradation through water erosion in tropical landscapes frequently exposes Cambisol B horizons characterized by high exchangeable aluminum toxicity, near-absent organic matter, and severely constrained biological functioning. This doctoral research evaluated the rehabilitation potential of coffee husk biochar (pyrolized at 600 °C; 0, 5, 10, and 20 Mg ha⁻¹) combined with two functionally contrasting cover crops, Brachiaria ruziziensis (C4 grass) and Crotalaria ochroleuca (N₂-fixing legume), applied to the B horizon of a Dystric Cambisol across two consecutive cropping cycles under greenhouse conditions without mineral fertilization. A completely randomized 4×2 factorial design with three replicates was used to assess physical, chemical, and biological soil responses. Regarding physical reconditioning, biochar at 5 Mg ha⁻¹ combined with Crotalaria maximized water permeability, whereas higher doses with Brachiaria increased microporosity and plant-available water but reduced macroporosity and aggregate stability. Chemically, a single biochar application progressively raised soil pH to 6.83 at 20 Mg ha⁻¹ by the second cycle, suppressed exchangeable Al³⁺ to zero at doses ≥ 10 Mg ha⁻¹ across both cycles, and reduced calcium leaching by over 95%. Soil organic carbon increased approximately 63% at the highest dose, and total nitrogen under Crotalaria at 20 Mg ha⁻¹ reached 0.78 g kg⁻¹, 45% above the species control, consistent with biochar-enabled biological nitrogen fixation. Concentrations of potentially toxic elements declined 15–32% over two cycles. Biologically, biochar rate significantly increased soil basal respiration (p = 0.0048) and β-glucosidase activity (p = 0.008), indicating selective early activation of microbial functioning, with Crotalaria treatments at intermediate to high doses showing the highest numerical values. Collectively, these results demonstrate that a single application of coffee husk biochar produces durable, dose-dependent improvements across the physical, chemical, and biological dimensions of a severely degraded tropical subsoil, with cover crop functional identity modulating the magnitude and direction of responses across successive cycles.

MEMBROS DA BANCA:
Externo à Instituição - DIEGO ANTÔNIO FRANÇA DE FREITAS - UFV (Membro)
Interno - JUNIOR CESAR AVANZI (Membro)
Interno - MARCO AURELIO CARBONE CARNEIRO (Membro)
Presidente - MARX LEANDRO NAVES SILVA (Membro)
Externo ao Programa - PEDRO MARANHA PECHE - DAG/ESAL (Suplente)
Externo à Instituição - YURI JACQUES AGRA BEZERRA DA SILVA - UFRPE (Suplente)
Externo à Instituição - BARBARA PEREIRA CHRISTOFARO SILVA - UNESP (Membro)