Banca de DEFESA: HELLEN FERNANDA OLIVEIRA DA SILVA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : HELLEN FERNANDA OLIVEIRA DA SILVA
DATE: 27/06/2025
TIME: 09:00
LOCAL: Online
TITLE:

Development and Agronomic Assessment of Phosphate Organomineral Fertilizers Based on Organic Residues for Use in Tropical Soils

KEY WORDS:

Organomineral fertilizers. Phosphorus. Vermicompost. Biochar. Raphanus sativus L.

PAGES: 172
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUBÁREA: Ciência do Solo
SPECIALTY: Química do Solo
SUMMARY:

Soil is essential for both agricultural productivity and environmental balance, acting as a support for plants and as a natural filter. Its functionality depends on the interaction between minerals, organic matter, air, water, and human interference. Pollution compromises this dynamic, demanding conscious and sustainable management. In this context, the central objective of this thesis was the development, characterization, and agronomic evaluation of phosphate organomineral fertilizers formulated from organic residues, with a special focus on the interaction between their constituent fractions, nutrient dynamics in the soil, and the effects on radish crop performance. In Chapter I, the physicochemical and spectroscopic characterization of the formulations revealed marked differences between the organic materials used. Vermicompost showed a higher proportion of aliphatic and oxygenated carbons, suggesting high bioavailability and rapid decomposition. In contrast, biochar was characterized by condensed aromatic structures, indicative of greater chemical stability. The hybrid composition made it possible to adjust the balance between nutrient release and retention, which is a positive point in terms of formulation flexibility. However, an excessive presence of biochar may hinder the immediate availability of nutrients, requiring caution regarding its proportion. Morphological analysis indicated that the granule structure was directly influenced by the P₂O₅ content. Formulations with 15% exhibited high porosity, which favors water retention and microbial activity, although they had a lower total phosphorus concentration. On the other hand, formulations with 40–45% P₂O₅ showed greater density and compactness, resulting in slower release, but with the risk of lower initial efficiency. The presence of molybdenum and the good homogenization of nutrients were positive points, while the challenge lies in maintaining the balance between mechanical strength and agronomic reactivity. In Chapter II, the dynamics of nutrient release and leaching were evaluated in sandy soil columns. The organomineral fertilizers raised the pH of the solution to values between 6.0 and 7.0, a beneficial effect in acidic soils, though it may compromise the solubility of certain micronutrients at high pH. Nitrogen and potassium leaching followed a cyclic pattern, with no significant differences compared to mineral fertilizer. In contrast, phosphorus loss was significantly higher in formulations with greater P₂O₅ content, especially in soils with low retention capacity, such as sandy soils. This represents an environmental challenge, as it indicates a potential risk of contamination of groundwater bodies. Therefore, formulation must consider not only agronomic efficiency but also environmental safety. In Chapter III, three selected formulations were evaluated in radish cultivation, under different doses and liming conditions. The NT3K treatment, with 15% P₂O₅ and liming, promoted the greatest increase in production, with up to 98.64% gain in fresh fruit weight, as well as improved commercial quality. The formulations with 40% (T8) and 45% (T9) P₂O₅ also performed better than conventional mineral fertilizer, although with lower gains. Liming enhanced the productive response by promoting phosphorus uptake. In some treatments, an increase in the incidence of cracking in tubers was observed, possibly due to accelerated growth, which represents a negative aspect related to visual product quality. Still, the results showed that the combination of vermicompost and biochar improves the physical and chemical properties of the soil, increases water and nutrient retention, and supports root development. In conclusion, the use of phosphate organomineral fertilizers represents a promising strategy for sustainable agriculture, especially in tropical soils, provided that formulations are carefully adjusted to maximize agronomic efficiency and minimize environmental risks.

COMMITTEE MEMBERS:
Presidente - 1399485 - ANDRES CALDERIN GARCIA
Interno - 387406 - RICARDO LUIZ LOURO BERBARA
Externa ao Programa - 1412091 - ERICA SOUTO ABREU LIMA - UFRRJExterna à Instituição - CAMILA PINHEIRO NOBRE - UEMA
Externo à Instituição - ORLANDO CARLOS HUERTAS TAVARES - UFRRJ