Soil Organic Matter Dynamics in Tropical Ecosystems

Soil organic matter (SOM) in tropical ecosystems governs a complex interplay between rapid biomass inputs and accelerated decomposition under warm, humid conditions. Plant litter and root exudates supply a continual stream of organic substrates that are transformed by diverse microbial communities and soil fauna into more stable compounds. The balance between mineralisation and stabilisation determines the overall soil carbon stocks, with clay minerals and microaggregate formation playing critical roles in protecting organic constituents from enzymatic breakdown. Seasonal moisture fluctuations and redox cycles further influence SOM turnover, favouring periodic pulses of nutrient release that sustain high primary productivity. Land-use change, such as conversion of forest to agriculture, can disrupt this equilibrium, leading to reduced carbon storage and altered nutrient cycling. Conversely, practices such as mulching, cover cropping and agroforestry enhance carbon inputs and promote aggregate stability. Understanding the mechanisms of SOM preservation is essential for optimising soil fertility, supporting tropical food security and mitigating global climate change through carbon sequestration strategies.

Research from Nature Portfolio

Recent studies have highlighted the importance of biotic processes in structuring tropical soil. Investigations into the activity of social insects in deeply weathered soils have revealed that termite and ant communities contribute significantly to microaggregate formation and overall physical fertility. The presence of specific clay minerals within these microaggregates points to a long-term biological imprint on soil structure, underscoring the reliance of Ferralsols on intact soil fauna for water retention and structural resilience.

Soil Organic Matter Dynamics in Tropical Ecosystems publication trend

The graph below shows the total number of articles in soil organic matter dynamics in tropical ecosystems across all publications each year (not limited to Nature Index journals).

Technical terms

Soil Organic Matter: The organic component of soil, including decomposed plant and animal residues plus microbial biomass.

Microaggregate: A small, stable cluster of soil particles bound by organic and inorganic agents, protecting organic matter from decomposition.

Cation Exchange Capacity (CEC): The soil’s ability to retain and exchange positively charged nutrient ions such as calcium, magnesium and potassium.

Base Cations: Essential nutrients (calcium, magnesium, potassium, sodium) that help maintain soil structure, pH and fertility.

Soil Bulk Density: A measure of soil compaction, expressed as the mass of dry soil per unit volume, influencing root growth and water infiltration.

References

1. Long-term activity of social insects responsible for the physical fertility of soils in the tropics. Scientific Reports (2023).
2. Understanding how management can prevent degradation of the structurally fragile soils of the Amazonian periphery. European Journal of Agronomy (2024).
3. Gliricidia sepium (Jacq.) Walp Applications for Enhancing Soil Fertility and Crop Nutritional Qualities: A Review. Forests (2023).
4. Soil carbon stock and emission: estimates from three land-use systems in Ghana. Ecological Processes (2021).