Effects of Fertilization and Planting Modes on Soil Organic Carbon and Microbial Community Formation of Tree Seedlings

Summary

This one-year pot trial in degraded plantation soil examined the effects of biochar and organic fertiliser applications on soil organic carbon accumulation and microbial community dynamics in forest tree seedling production. The combined application of tea seed shell biochar and tea meal organic fertiliser (BCF treatment) was most effective at increasing SOC, improving soil pH and nutrient availability, and promoting seedling growth of two native tree species. The results indicate that fertilisation-driven shifts in bacterial community composition—particularly enrichment of eutrophic groups (Ascomycota and Proteobacteria) and suppression of oligotrophic groups (Acidobacteria and Basidiomycetes)—play a key role in organic carbon formation and tree establishment in forest restoration contexts.

UK applicability

The findings may have limited direct applicability to UK forest systems, given the use of warm-climate tree species and the focus on restoring degraded plantation soils in tropical/subtropical conditions. However, the mechanistic insights into how biochar and organic amendments promote soil carbon retention and beneficial microbial communities could inform UK woodland management practices, particularly in soil remediation and agroforestry systems.

Key measures

Soil organic carbon (SOC), soil pH, available nutrients (phosphorus), microbial biomass carbon (MBC), bacterial and fungal community composition (16S rRNA and ITS sequencing), seedling above-ground and below-ground biomass, plant height

Outcomes reported

The study measured soil organic carbon (SOC) content, soil pH, available nutrient concentrations, microbial community composition (bacterial and fungal), microbial biomass carbon (MBC), and seedling growth metrics (biomass and plant height) across four fertilisation treatments and three planting mode ratios over one year.

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