Biological activity

Definition

Biological activity refers to the processes and interactions of living organisms, such as plants, microorganisms, and animals, within a soil environment that influence its characteristics and behavior. This activity plays a crucial role in shaping soil properties, including its shear strength, by affecting factors like drainage conditions, soil composition, and the history of stress applied to the soil.

5 Must Know Facts For Your Next Test

1. Biological activity can enhance soil structure by promoting the formation of aggregates, which improves aeration and water infiltration.
2. Microorganisms play a key role in decomposing organic matter, releasing nutrients that contribute to plant growth and affect soil shear strength.
3. The level of biological activity in the soil can vary based on drainage conditions; well-drained soils often support higher microbial populations.
4. Soil types with high organic matter content typically exhibit greater biological activity, leading to improved cohesion and increased shear strength.
5. Changes in biological activity due to environmental factors or human interventions can lead to variations in soil stability and behavior under load.

Review Questions

• How does biological activity influence the drainage conditions within a soil environment?
  • Biological activity significantly impacts drainage conditions by promoting soil aggregation through the action of microorganisms. These aggregates create larger pore spaces that enhance water movement and retention. Furthermore, plants' root systems contribute to this process by creating channels in the soil, which helps improve drainage and reduces surface runoff.
• Discuss how different soil types can affect biological activity and subsequently influence shear strength.
  • Different soil types vary in their composition and structure, which directly affects biological activity. For instance, sandy soils typically have lower organic matter content and less capacity for retaining moisture, resulting in reduced microbial activity compared to clay soils that hold more nutrients and moisture. This difference in biological activity leads to variations in shear strength; soils with higher microbial presence tend to have improved cohesion and resistance to shear forces.
• Evaluate the impact of stress history on biological activity and its implications for soil shear strength over time.
  • Stress history plays a crucial role in determining the biological activity present in a soil profile. Soils that have been subjected to repeated loading may experience compaction, which limits pore space and reduces habitat for microorganisms. Over time, this decrease in biological activity can lead to diminished organic matter decomposition rates and nutrient cycling. As a result, soils with reduced biological activity may exhibit lower shear strength and stability under loads compared to those with a history of less stress.

Related terms

Soil Microorganisms: These are tiny living organisms in the soil, such as bacteria and fungi, that contribute to nutrient cycling, organic matter decomposition, and overall soil health.

Organic Matter: Decomposed plant and animal residues in the soil that improve its structure, water retention, and nutrient availability.

Shear Strength:

The resistance of soil to shearing forces, which is influenced by factors like moisture content, density, and biological activity.