DSpace Coleção: Artigo em periódico indexado (CPAC)

Sewage sludge biochar-based fertilizer enriched with K-bearing silicate agrominerals and oxalic acid: physicochemical characterization and carbon stability.

Thu, 01 Jan 2026 00:00:00 GMT

Título: Sewage sludge biochar-based fertilizer enriched with K-bearing silicate agrominerals and oxalic acid: physicochemical characterization and carbon stability. Autoria: SANTOS, M. G. B. dos; LUSTOSA FILHO, J. F.; COSTA, C. R.; LIMA, B. C.; D'ÁVILA, M. L.; OLIVEIRA, S. S. de; MENDES, G. de O.; MARTINS, E. de S.; MARCHI, G.; FIGUEIREDO, C. C. de Conteúdo: Abstract: The synthesis of biochar-based fertilizers (BBFs) from urban waste and agrominerals represents a promising approach to advancing a circular economy and agricultural sustainability. In this study, 16 BBFs were synthesized from pyrolyzed sewage sludge biochar at 300 °C and 500 °C (SSB300 and SSB500), potassium-rich silicate agrominerals (ASi) such as mica schist and phonolite, and different concentrations of oxalic acid (OA): 0; 0.33; 0.67 and 1 mol L−1. The formulations were characterized in terms of chemical, physical, and mineralogical composition, structural properties, and carbon (C) stability. The pyrolysis temperature was the main factor responsible for the structural stability of C. Materials produced at 500 °C showed greater aromaticity, lower H/C and O/C ratios, lower ratios between volatile material (VM) and fixed C (FC) (VM/FC), and higher recalcitrance (R50) and thermostable fraction (TSF) values, indicating greater recalcitrance and structural stability, with emphasis on SSB500+Mica + OA0 and SSB500+Phon + OA0. In contrast, formulations with SSB at 300 °C exhibited greater surface functionalization and enhanced potential for chemical reactivity, particularly at higher OA concentrations, with emphasis on SSB300+Phon + OA1. The OA application altered the mineral matrix and the structure of C, promoting greater surface functionalization and potentially nutrient availability, although with a slight reduction in C recalcitrance. The incorporation of ASi increased the total K content and promoted mineral compositional differentiation in the new fertilizers. The results suggest that the developed BBFs constitute highly tunable organomineral systems, in which the manipulation of pyrolysis temperature and chemical activation enables targeted modulation of the balance between C structural stability and reactivity. Although OA reduces the stability of C, our results show that it is possible to synthesize formulations tailored either for greater structural stability (SSB500-based) or for enhanced reactivity and potential nutrient release (SSB300+OA-based), depending on the intended agronomic application. This approach may contribute to the rational design of multifunctional fertilizers, enabling the development of formulations tailored to diverse management strategies and soil conditions.

Agronomic evaluation of nepheline syenite as a Potassium source for soybean and maize grown in a Red Latosol.

Thu, 01 Jan 2026 00:00:00 GMT

Título: Agronomic evaluation of nepheline syenite as a Potassium source for soybean and maize grown in a Red Latosol. Autoria: FRANÇA, D. M.; SANTOS, L. F. dos; BAVARESCO, L. G.; MARCANTE, N. C.; MARCHI, G.; MARTINS, E. de S. Conteúdo: Objective: To evaluate the agronomic efficiency of nepheline syenite (NS) as a potassium (K) source for soybean and maize crops during the 2021/2022 and 2022/2023 growing seasons, in comparison with KCl. Method: The experimental design was a randomized complete block with four replications. The K rates applied were 0; 70, and 140 kg K₂O ha⁻¹. For the 140 kg K₂O ha⁻¹ rate, eight plots were established: four were evaluated in both the first and second seasons, and four were evaluated only in the second season, when they received an additional 70 kg K₂O ha⁻¹, resulting in a total of 140 + 70 kg K₂O ha⁻¹. Results and Conclusion: Soybean yield with NS was similar to the control and lower than that obtained with KCl in the 2021/2022 season. In the following season, 140 kg K₂O ha⁻¹ applied via NS increased soybean yield by up to 8%. In maize, the highest yields were obtained with 140 + 70 kg K₂O ha⁻¹ applied via NS (7%) and KCl (8%). At this rate, final soil K contents increased by up to 26% with NS. A residual effect of NS was observed, as well as similar agronomic efficiency between NS and KCl at the 140 + 70 kg K₂O ha⁻¹ rate.

Dynamics of potassium and phosphorus uptake in soybean cultivated on oxisol amended with biotite schist and potassium chloride.

Thu, 01 Jan 2026 00:00:00 GMT

Título: Dynamics of potassium and phosphorus uptake in soybean cultivated on oxisol amended with biotite schist and potassium chloride. Autoria: MARCHI, G.; FREITAS, E. M. de; KRAHL, L. L.; ABRANTES, E. G. de; RODRIGUES, P. C. F.; SOUZA-SILVA, J. C.; SOARES, J. P. G.; MARTINS, E. de S. Conteúdo: Abstract: Phosphorus (P) is an essential macronutrient for plant growth, but its availability to plants is often limited in acidic tropical soils by iron (Fe) and aluminum (Al) (hydr)oxides, which strongly adsorb and immobilize phosphate. This study evaluated soybean (Glycine max L. BRS 7582) growth in soil amended with biotite schist and a soluble potassium (K) source, potassium chloride (KCl). The experiment involved pots with dystrophic Rhodic Haplustox soil; treatments were composed by control, as KCl (KCl-T), 1% biotite schist (BSO) and biotite schist + 150 mg K kg⁻¹ as KCl (BS + KCl), with all treatments receiving 100 mg P kg⁻¹ as calcium dihydrogen phosphate [Ca(H₂PO₄)₂]. Results showed that KCl-T promoted greater shoot growth than the other treatments, presenting 9.0%, 11.9%, and 41.1% higher dry mass production compared to the BS + KCl, BSO, and control treatments, respectively. Across all sampling times, K concentration in soybean shoots was significantly higher in treatments receiving soluble K (KCl‑T and BS + KCl) than in the control (p < 0.001). Values ranged from 11.3 to 19.4 g K kg⁻¹ in KCl‑based treatments, whereas the control remained below 6.7 g K kg⁻¹ at all evaluation times, with BSO showing intermediate values. Notably, on the 47 day after planting, plant P uptake was statistically similar among BSO, BS + KCl, and KCl-T treatments (2.15 g P kg− 1; p < 0.0001). Soil P extractability, measured by Mehlich-1, after 37 and 47 days, increased 15.29 and 22.62% (both p < 0.0001) in the presence of biotite (BSO and BS + KCl), as compared to treatments without biotite (KCl-T and control); this pattern is consistent with an increase in oxalate‑extractable, poorly crystalline (short‑range ordered) Fe released during bioweathering, which may have contributed to P adsorption and Mehlich-extraction compared to crystalline iron/aluminum oxyhydroxides.

The impact of melatonin on cellular dynamics and gene expression of bovine embryos cultured under low and high oxygen tension.

Thu, 01 Jan 2026 00:00:00 GMT

Título: The impact of melatonin on cellular dynamics and gene expression of bovine embryos cultured under low and high oxygen tension. Autoria: OLIVEIRA, I. R. dos S.; MARTINS, C. F.; RODRIGUES, F. L.; MELLO, V. C.; RODRIGUES, M. T. de O.; FARIA, L. C. de; AMARAL, H. B. S.; ANDRADE, R. V. de; FONSECA, M. J. P.; DODE, M. A. N.; BÁO, S. N. Conteúdo: This study investigated the effects of melatonin supplementation in the culture medium on the development, cellular dynamics and gene expression of bovine embryos produced in vitro under low (5%) or high (20%) oxygen tension. Zygotes were cultured without melatonin or with (10−9 M), and cleavage, blastocyst rates, blastomere number, apoptosis, mitochondrial activity, lipid accumulation, and expression of genes related to metabolism, oxidative stress and embryo quality were evaluated. Under high O₂ tension, melatonin increased blastocyst rate (39.8% vs. 34.0%), raised blastomere number, reduced apoptosis, and decreased lipid accumulation. It also upregulated SOD2, KRT8, IFN-τ, and PLAC8. Under low O₂ tension, melatonin increased cleavage rate and mitochondrial activity but did not affect blastocyst rate; only SOD2 was upregulated. Embryos cultured without melatonin under low O₂ showed higher IFN-τ and PLAC8 expression. In conclusion, melatonin improves embryo quality and viability mainly under high oxygen tension, acting as an antioxidant, gene modulator and apoptosis inhibitor. Its effects are more limited under low O2, likely because this environment is closer to physiological conditions and requires fewer responses to oxidative stress.