Bacterial fertilizer and filtered sludge enhance soil fertility and plant growth in a eucalyptus plantation

Plant growth-promoting rhizobacteria (PGPR) and filtered sludge are widely used to improve soil fertility and plant yields. In this study, we evaluated the impact of sludge and/or PGPR application on the nutrient contents and enzyme activities of the soil as well as on plant growth. We planted bare-root eucalyptus seedlings in (1) soil amended with filtered sludge from Nanning sugar factory (FS), (2) soil amended with filtered sludge + PGPR (BF), and (3) non-amended soil (control). Soil fertility and eucalyptus growth were determined after 3, 6, 9, and 12 months. Results demonstrated that FS treatment significantly increased eucalyptus growth compared to the control, particularly after six months. Bacterial fertilizer (BF) also increased soil urease and sucrase activities, although differences diminished over the study period. Our findings suggest that the integration of bacterial fertilizers and filtered sludge can serve as an effective and environmentally friendly strategy to improve soil health and promote sustainable eucalyptus cultivation. This research contributes to the growing body of evidence supporting the use of bio-fertilizers in forestry practices, highlighting their potential to reduce or replace the use of chemical fertilizers while increasing plant productivity.