Soil Drums and Microbial Rhythms: Compartment-specific responses of soil, root, and earthworm gut microbiomes to Terra Preta de Índio–inspired amendments

Summary

This experimental study evaluated how biochar, manure, and earthworms—applied individually and in combination—shaped bacterial community structure across three ecological compartments (bulk soil, maize roots, earthworm gut) in a nutrient-poor tropical Latosol. The synergistic Terra Preta-inspired treatment generated unique non-additive microbial trajectories and significantly exceeded individual treatments in supporting maize growth, with Bradyrhizobium emerging as a key indicator of system function. The findings suggest that integrated management mimicking Amazonian Dark Earth principles creates multi-process ecological interventions that enhance soil fertility through coordinated shifts in microbial structure and function.

Regional applicability

The study was conducted in Brazil using tropical Latosol under controlled greenhouse conditions, limiting direct transferability to United Kingdom temperate agroecosystems, which have markedly different soil types, climate, and microbial communities. However, the underlying principles of synergistic amendment integration and compartment-specific microbial responses may offer insights for United Kingdom soil health management and regenerative farming practices, though UK field validation would be necessary.

Key measures

16S rRNA gene sequencing, bacterial community composition and network topology, exchangeable iron, soil pH, nutrient status, maize plant biomass/growth, indicator taxa (Bradyrhizobium)

Outcomes reported

The study measured bacterial community composition across soil, root, and earthworm gut compartments using 16S rRNA gene sequencing, and assessed maize growth performance under different amendment treatments. It identified non-additive microbial and agronomic responses to Terra Preta-inspired amendments combining biochar, manure, earthworms, and plant cultivation.

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