Soils and Aquatics Envirothon

What is the scientific definition of soil?

Soil is a natural body consisting of layers (horizons) of mineral and organic constituents that differ from their parent materials in physical, chemical, and biological properties.

Why is soil important?

Soil supports plant growth, regulates water, recycles nutrients, supports biodiversity, and serves as a foundation for infrastructure.

How is soil color measured?

Using the Munsell Soil Color Chart

What do red, yellow, and gray soil colors typically indicate?

Red/yellow = oxidized iron (well-aerated); gray = reduced iron (poorly drained, anaerobic).

What are the soil separates and their sizes?

Sand (0.05–2 mm), Silt (0.002–0.05 mm), Clay (<0.002 mm)

How does soil texture affect water retention?

Clay holds water well, sand drains quickly, and silt retains moderate moisture.

What is soil structure and why is it important?

Soil structure is the arrangement of soil particles into aggregates; it affects aeration, root growth, and water movement.

What are the five soil-forming factors?

Parent material, climate, topography, organisms, and time.

What are the six major soil horizons?

O (organic), A (topsoil), E (eluviation), B (subsoil), C (parent material), R (bedrock)

What is organic matter and why is it important?

Decomposed plant and animal residues; it improves nutrient holding, water retention, and soil structure.

What roles do sand, silt, and clay play in soil?

Sand improves drainage, silt helps hold nutrients, clay stores water and nutrients but may cause compaction.

What are the 12 USDA soil orders?

Alfisols, Andisols, Aridisols, Entisols, Gelisols, Histosols, Inceptisols, Mollisols, Oxisols, Spodosols, Ultisols, Vertisols

What is the Web Soil Survey?

A USDA NRCS tool providing access to soil data for over 95% of the U.S. land mass.

What can you learn from a soil survey?

Soil types, suitability for land uses, limitations for development, erosion risk, etc.

What is the Land Capability Classification System?

A system that ranks soil from Class I (fewest limitations) to Class VIII (unsuitable for cultivation).

What factors are considered in land use decisions involving soils?

Drainage, erosion potential, slope, fertility, and structure.

What are the four principles of soil health?

Keep soil covered, minimize disturbance, maximize diversity, and keep living roots in the soil.

What are physical, chemical, and biological indicators of soil health?

Structure/aggregation, pH/nutrient levels, and microbial activity/earthworms.

Name three benefits of healthy soil.

Enhanced crop yield, improved water filtration, and greater resilience to drought/flood.

What are the main types of soil erosion?

Sheet, rill, gully, and wind erosion

What are BMPs for preventing erosion?

Cover crops, contour plowing, terraces, no-till farming, riparian buffers.

What is a hydric soil?

A soil formed under saturated conditions long enough to develop anaerobic conditions.

How does composting benefit soil?

Increases organic matter, improves structure, supports microbial life, retains water.

How does soil relate to home sewage systems?

Soil percolation rate and drainage determine system effectiveness and environmental safety.

What do Major Land Resource Areas (MLRAs) in SC tell us?

They indicate region-specific soil, geology, climate, and potential land use practices.

What are the four main physical and chemical properties of water that affect aquatic life?

Polarity, temperature, pH, and dissolved oxygen

What are the stages of the water cycle?

Evaporation, condensation, precipitation, infiltration, runoff, and transpiration

What percentage of Earth's water is freshwater?

About 2.5%

What is brackish water and where is it found?

A mix of freshwater and saltwater, typically found in estuaries

Name the main types of aquatic ecosystems.

Oceans, lakes, rivers, streams, and wetlands

What are the three main components of an aquatic ecosystem?

Biotic factors (species/communities), abiotic factors, and symbiotic relationships

What is an aquifer?

A porous rock layer that stores groundwater

What is a water table?

The upper surface of groundwater below which the soil is saturated

How do seasonal changes affect aquatic ecosystems?

They affect temperature, nutrient levels, runoff, and flow rates

What is eutrophication?

Nutrient enrichment leading to algal blooms and oxygen depletion

What is an aquatic food web?

A diagram showing energy flow among producers, consumers, and decomposers

What does the energy pyramid show?

The amount of energy available decreases at each trophic level

What is stream order and why does it matter?

A method to classify streams based on hierarchy; affects flow, organisms, and habitat

What are watersheds and why are they important?

Areas where all precipitation drains to a common outlet; key to water quality

What are producers, consumers, and decomposers in aquatic ecosystems?

Producers (algae), consumers (fish), decomposers (bacteria)

What is an adaptation of aquatic plants?

Aerenchyma tissue for buoyancy or flexible stems for flow resistance

Name three adaptations of aquatic animals.

Streamlined bodies, countershading, gills

What are cyanobacteria and why are they important?

Photosynthetic bacteria; they can cause harmful algal blooms

What does anadromy mean?

Fish migrate from saltwater to freshwater to spawn (e.g., salmon)

Define “endemic” species.

Species native to a specific, restricted geographic area

What is point-source pollution?

Pollution from a single source, like a pipe or ditch

What is non-point source pollution?

Pollution from diffuse sources like runoff from farms or streets

Name three SC agencies that manage water quality.

SC DHEC, SC DNR, USGS

Why is watershed-level planning important?

Because water flows across political boundaries and land uses

What is hypoxia?

Low dissolved oxygen levels, harmful to aquatic life

What is cultural eutrophication?

Human-caused nutrient enrichment in water bodies

What is ocean acidification?

CO₂ absorption lowering ocean pH, harming shell-forming organisms

How does climate change affect water quality?

Increases stormwater runoff, droughts, and water temperature

What is a riparian buffer and what does it do?

Vegetated area next to water that filters runoff and provides habitat

Name two pollution-sensitive macroinvertebrates.

Mayflies, stoneflies

What does a biotic index measure?

Water quality based on macroinvertebrate diversity

What does a Secchi disk measure?

Water clarity

What is a hydrograph used for?

To track water discharge over time

How do you delineate a watershed on a topo map?

By drawing lines along ridges that separate drainage areas

What does high turbidity indicate?

Poor water clarity, often due to suspended sediments or algae

What are common tools for water testing?

pH meter, dissolved oxygen probe, thermometer, nitrate test kits

What is base flow in a stream?

The portion of streamflow from groundwater during dry weather

What is the water budget equation?

Precipitation = Runoff + Evapotranspiration + Change in Storage