Soil organic matter (SOM) is formed through the breakdown of plant material by soil organisms.
Understanding Soil Organic Matter Formation
Soil organic matter, or SOM, is crucial for healthy soil. It's not just decayed plant matter; it's a complex mix of materials at various stages of decomposition. Here's a breakdown of how it's formed:
The Process of SOM Formation
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Plant Inputs: The primary source of SOM is organic material from plants. This includes:
- Above-ground litter: Leaves, stems, and branches that fall to the soil surface.
- Below-ground litter: Roots that die and decompose in the soil.
- Exudates: Substances released by plant roots into the surrounding soil.
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Decomposition by Soil Organisms: Soil organisms, such as:
- Bacteria
- Fungi
- Earthworms
- Nematodes
These organisms feed on plant inputs and break them down through partial decomposition and transformation. This process releases nutrients that are vital for plant growth. The byproducts of this decomposition then contribute to the formation of SOM.
Key Elements in SOM Formation:
| Element | Role |
|---|---|
| Plant Inputs | Provide the raw materials for SOM (litter, exudates, etc.) |
| Soil Organisms | Carry out the decomposition, leading to SOM formation |
| Partial Decomposition | Breaks down plant materials into smaller and simpler substances |
| Transformation | Modifies and converts decomposed material into the complex SOM |
Practical Insights
- Maintaining Soil Health:
- Adding organic materials such as compost and mulch can encourage SOM formation.
- Reducing tillage helps protect the soil structure and allows for greater SOM buildup.
- Benefits of SOM: SOM contributes to:
- Improved soil structure
- Enhanced water retention
- Increased nutrient availability
- Greater carbon storage.
Reference:
Soil organic matter (SOM) is formed through the partial decomposition and transformation of plant inputs (for example, above- and below-ground litter and exudates) by soil organisms.07-Sept-2015
In essence, soil organic matter is a dynamic product of nature, a crucial part of healthy ecosystems, and continuously formed through biological processes.
