Theme 2 Flashcards
(32 cards)
What are the three primary phases of soil?
Solid Phase, Liquid Phase, Gaseous Phase
Solid Phase includes inorganic and organic matter. Liquid Phase consists of soil solution. Gaseous Phase contains soil air.
What is found in the solid phase of soil?
Inorganic matter and organic matter
Inorganic matter includes minerals like sand, silt, and clay. Organic matter consists of decomposed plant and animal residues.
What is the role of soil solution?
Transports nutrients to plant roots and microbes
Essential for nutrient transport and microbial activity.
What does soil air facilitate?
Gas exchange, supporting aeronic respiration and root health.
Supports aerobic respiration and root health.
What is pore space in soil?
The voids between soil particles, filled with water and air
Regulates water infiltration, storage, and drainage.
How does pore space affect hydrology?
Regulates water infiltration, storage, and drainage
Influences nutrient transport and gas exchange.
How does soil interact with the hydrosphere?
Stores and filters water
Influences groundwater recharge and surface runoff.
What are the consequences of soil compaction?
Reduces pore space and connectivity
Limits infiltration
Decrease aeration
Decrease in profile available water
Limits water infiltration, aeration, and root growth.
What is gravimetric water content (θg)?
Mass of water per unit mass of dry soil
Indicates the amount of moisture in soil.
Define bulk density (ρb).
Mass of dry soil per unit volume of soil (including pores)
Indicates soil compaction.
What is porosity?
Volume of pore space per unit volume of soil
Critical for water and air movement.
What does the degree of saturation (s) represent?
Proportion of pore space filled with water
Important for understanding water availability.
What is the void ratio (e)?
Ratio of pore volume to solid volume
Helps in assessing soil structure.
What is particle density (ρs)?
Mass of soil solids per unit volume of solids (excluding pores)
Useful for calculating soil properties.
What does volumetric water content (θw) indicate?
Volume of water per unit volume of soil
Reflects soil moisture status.
What causes soil compaction?
Heavy machinery, overgrazing, intensive farming
All lead to reduced pore volume and connectivity.
How does bulk density indicate soil degradation?
High bulk density indicates compaction and reduced pore space
Used to assess soil health.
What affects water retention in soil?
Soil texture and organic matter
Key factors influencing soil properties.
What is soil texture?
Relative proportions of sand, silt, and clay in a soil
Influences water retention, aeration, and nutrient availability.
What are the particle size ranges for sand, silt, and clay?
Sand: 0.05–2 mm, Silt: 0.002–0.05 mm, Clay: <0.002 mm
Important for soil classification.
What is the role of clay-sized particles?
High surface area and negative charge for nutrient adsorption
Contributes to soil fertility.
What is the effect of high clay content on water retention?
Increases water retention but reduces drainage and aeration
Critical for managing water in soils.
What are the characteristics of sandy soils?
High drainage, low fertility, poor nutrient retention
Easy to work with.
What are loess soils?
Fine-grained, wind-deposited sediment primarily composed of silt
Highly fertile and important for agriculture.
