Organic Matter

Definition

Organic matter refers to the decomposed remains of plants and animals, along with other carbon-based compounds, that enrich the soil and support a healthy ecosystem. This substance plays a critical role in soil formation, enhancing soil structure, nutrient availability, and water retention while also being vital in the phosphorus cycle, influencing its mobility and availability in water bodies.

5 Must Know Facts For Your Next Test

1. Organic matter improves soil structure by promoting aggregation, which enhances aeration and water infiltration.
2. The decomposition of organic matter releases essential nutrients like nitrogen, phosphorus, and sulfur, which are crucial for plant growth.
3. Higher organic matter content in soils typically leads to better moisture retention, reducing irrigation needs and improving drought resilience.
4. In aquatic systems, organic matter influences the phosphorus cycle by serving as a source of nutrients that can lead to algal blooms when it enters water bodies.
5. Organic matter acts as a carbon sink, helping mitigate climate change by sequestering carbon dioxide from the atmosphere into the soil.

Review Questions

• How does organic matter contribute to soil formation and its overall health?
  • Organic matter is a key component in soil formation as it originates from the decomposition of plant and animal material. It enhances soil structure by improving aggregation, which allows for better air and water movement through the soil. This enriched environment supports diverse microbial life, leading to a more resilient ecosystem that can sustain plant growth and maintain nutrient cycling.
• Discuss the role of organic matter in the phosphorus cycle and its impact on water quality.
  • Organic matter plays a crucial role in the phosphorus cycle by providing a source of nutrients that can be released during decomposition. This process affects the availability of phosphorus in soils, which can then leach into nearby water bodies through runoff. An excess of phosphorus can lead to eutrophication, resulting in harmful algal blooms that deplete oxygen levels in water and harm aquatic life.
• Evaluate the implications of reduced organic matter in soils on both terrestrial ecosystems and aquatic environments.
  • A decrease in organic matter in soils can lead to poorer soil structure, reduced nutrient availability, and diminished water retention capabilities. This decline affects terrestrial ecosystems by limiting plant growth and biodiversity. In aquatic environments, reduced organic matter can alter nutrient dynamics, increasing the likelihood of eutrophication as nutrients become more concentrated. Consequently, this can create dead zones in water bodies where aquatic life struggles to survive due to low oxygen levels.

Related terms

Humus: A dark, organic material in soil formed from the decomposition of plant and animal matter, crucial for soil fertility.

Nutrient Cycling:

The movement and exchange of organic and inorganic matter back into the production of living matter, essential for sustaining ecosystems.

Eutrophication:

A process where water bodies become overly enriched with nutrients, often due to runoff containing excess phosphorus and nitrogen, leading to algae blooms and degraded water quality.