Production of Basil and Eucalyptus Seedlings in Substrates Amended with Biochars Derived from Municipal Solid Waste and Lemongrass Biomass
The reuse of municipal solid waste and agro-industrial biomass has been considered a potential alternative to promote environmental sustainability and the circular economy. In this context, the present study evaluated the agronomic potential of biochars produced from municipal solid waste (BMSW) and lemongrass biomass (BCL), incorporated at different concentrations (5.0, 7.5, and 10.0 wt %) into a commercial substrate to produce basil (Ocimum basilicum) and eucalyptus (Eucalyptus grandis) seedlings. Biometric parameters and nutritional content of the plants were evaluated. The biochars were characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) to identify surface functional groups and mineral phases. The analyses indicated differences in the chemical and structural composition of the materials. The results demonstrated that the responses varied according to the plant species and the biochar source. BCL was associated with a greater biometric development of basil seedlings, especially in root growth, while BMSW was linked to a greater development of the aerial part of eucalyptus seedlings, mainly at concentrations of 5.0 and 7.5 wt %. In both species, the incorporation of biochars possibly yielded the accumulation of dry biomass. Regarding nutrients, potassium content was higher in treatments with 7.5 wt % BCL, reaching 15.3 g kg–1 in basil and 24.3 g·kg–1 in eucalyptus. For eucalyptus, the highest calcium levels were observed in treatments with BMSW, while higher boron levels were found in basil grown with 10.0 wt % of this biochar. Overall, the results indicate that the agronomic performance of biochars depends on their physicochemical properties and the interaction with the specific requirements of each plant species. However, the interpretations related to the action mechanisms must be considered cautiously since pH, electrical conductivity, porosity, water retention capacity, nutrient availability, and other physical-chemical Properties of the substrate blends after biochar incorporation were not measured. Thus, the results represent preliminary evidence obtained under controlled greenhouse conditions, highlighting the potential of biochars derived from waste as substrate conditioners in seedling production.