Soil Basics and Agriculture

A comprehensive set of vocabulary flashcards covering key concepts about soil, its formation, characteristics, and associated agricultural practices.

What is Soil?

A mixture of weathered rock, organic matter (humus), air, and water that supports plant growth.

What is Humus?

Decomposed organic matter that adds nutrients and improves soil structure.

What is Parent Material?

The underlying rock or sediment from which soil forms.

Soil Formation

Processes that form soil through weathering of rock and decomposition of organic matter over time.

Factors Influencing Soil Formation

Climate, organisms, topography, parent material, and time.

O Horizon

Organic layer made of leaves, plants, and humus.

A Horizon

Topsoil; most fertile layer with roots and organisms.

B Horizon

Subsoil; contains minerals leached from above.

C Horizon

Partially weathered parent material.

R Horizon

Bedrock.

Soil Texture

The proportion of sand, silt, and clay in soil.

Sandy Soil Characteristics

Large particles, drains quickly, low nutrient retention.

Silt Soil Characteristics

Medium particles, holds water better than sand.

Clay Soil Characteristics

Small particles, holds water well, poor drainage.

Loam

A balanced mix of sand, silt, and clay; best for farming.

Soil Degradation

Decline in soil quality and productivity.

Erosion

Removal of topsoil by wind or water.

Impact of Erosion

It removes nutrient-rich topsoil and reduces crop yields.

Human Activities Increasing Erosion

Tilling, deforestation, overgrazing.

Salinization

Buildup of salt in soil due to evaporation of irrigation water.

Impact of Salinization on Crops

Excess salt prevents plants from absorbing water.

Waterlogging

Soil becomes saturated with water.

Impact of Waterlogging

Roots lack oxygen, causing plant stress or death.

Watershed

An area of land where all water drains into a common body of water.

Components of a Watershed

Streams, rivers, tributaries, groundwater, and runoff.

Importance of Watersheds

They determine water availability and water quality.

Runoff

Water that flows over land into bodies of water.

Infiltration

Water soaking into the ground.

Problem with Runoff

It carries pollutants like fertilizers and pesticides into waterways.

Agriculture's Impact on Watersheds

Fertilizer and pesticide runoff pollutes water.

Urbanization's Impact on Watersheds

Impermeable surfaces increase runoff and reduce infiltration.

Deforestation's Impact on Watersheds

Increases erosion and runoff.

Riparian Buffer

Vegetated area near water that reduces runoff and erosion.

Wetlands Protection of Watersheds

They filter pollutants and absorb excess water.

Reducing Watershed Pollution

Reduce fertilizer use.

Industrial Agriculture

Large-scale farming using machinery, fertilizers, and pesticides.

Subsistence Agriculture

Small-scale farming to feed a family or community.

Monoculture

Growing one crop species over a large area.

Benefit of Monoculture

High efficiency and high yields.

Drawback of Monoculture

Increased vulnerability to pests and disease.

Irrigation

Artificial watering of crops.

Irrigation Methods

Flood, drip, and center pivot.

Problem Caused by Irrigation

Water depletion and salinization.

Sustainable Agriculture

Farming that maintains soil health and reduces environmental impact.

Crop Rotation

Planting different crops each season to maintain soil nutrients.

Cover Crops

Plants grown to protect soil between harvests.

Contour Plowing

Plowing along land contours to reduce erosion.

Terracing

Creating steps on slopes to reduce erosion.

Reduced Tillage

Minimizing soil disturbance to prevent erosion.

Organic Farming

Farming without synthetic fertilizers or pesticides.

What is the Tragedy of the Commons?

When shared resources are overused or depleted because individuals act in self-interest.

Give one marine and one terrestrial example of the Tragedy of the Commons.

Marine: overfishing. Terrestrial: overgrazing.

What is an ecological footprint?

A measure of how much land and water resources an individual or population uses to produce the resources they consume and absorb waste.

How do your food choices affect your ecological footprint?

Foods that require more resources (like beef) increase your footprint; reducing meat consumption can significantly reduce it.

What does sustainability refer to?

Using resources in a way that meets current needs without depleting them for future generations.

What are environmental indicators? Give examples.

Measures that show how sustainably we use resources, e.g., biodiversity, food production, global temperatures, CO₂, human population, resource depletion.

What is a maximum sustainable yield (MSY)?

The largest number of individuals that can be harvested from a population without reducing its ability to recover.

If a population has a carrying capacity of 2000 and doubles every year, what is the maximum sustainable yield for this organism?

MSY = half the carrying capacity growth; max growth occurs at K/2, so MSY ≈ 1000 individuals.

What is clearcutting?

Removing all trees from an area at once; economically advantageous but causes erosion, habitat loss, and reduced biodiversity.

What is selective cutting?

Removing only some trees, less disruptive than clearcutting.

Name two ecosystem services lost when forests are clearcut.

Carbon storage and water regulation.

What is deforestation and how does it contribute to climate change?

Permanent removal of forests; contributes to climate change by releasing CO₂ and reducing carbon sequestration.

Give one solution to prevent deforestation (not just “stop cutting”).

Reforestation, sustainable logging practices, or creating protected areas.

What are prescribed burns and why are they used?

Controlled fires used to reduce fuel buildup, prevent larger wildfires, and maintain ecosystem health.

How can bark beetles be controlled using IPM? Give method type.

Example: Introduce natural predators (biological IPM) to control beetles.

What was the goal of the Green Revolution?

Increase food production and reduce global hunger.

List 4–5 strategies/methods used in the Green Revolution.

1. High-yield crops, 2. Synthetic fertilizers, 3. Irrigation, 4. Pesticides, 5. Mechanization.

Name 5–6 inputs required for industrialized agriculture.

Water, energy, machinery, fertilizers, pesticides, capital.

List 2 positive and 2 negative impacts of the Green Revolution.

Positive: higher yields, reduced hunger. Negative: environmental pollution, increased pesticide/fertilizer use.

What is the pesticide treadmill?

Cycle where pests evolve resistance, requiring stronger or more pesticides, creating more resistance over time.

What type of pesticide is preferred: broad/narrow spectrum, persistent/non-persistent? Why?

Narrow-spectrum and non-persistent to target specific pests and reduce environmental impact.

What is the goal of Integrated Pest Management (IPM)?

To control pests sustainably using multiple methods while reducing harm to humans, wildlife, and the environment.

Give one example of an IPM method for each category.

Chemical: targeted pesticide

Biological: natural predators

Physical: traps/barriers

Cultural: crop rotation or companion planting

Compare CAFOs and free-range grazing.

CAFOs: high density, more efficient but polluting. Free-range: animals graze naturally, less pollution but lower efficiency.

Name 4 environmental benefits of reducing meat consumption.

Lower GHGs, less land use, less water use, less pollution.

What is overgrazing?

Too many animals feeding on land, reducing soil fertility and causing erosion.

What is rotational grazing?

Moving animals between pastures to allow grass recovery.

What is desertification?

Degradation of land into desert due to human activities like overgrazing, deforestation, and poor agriculture.

List soil conservation methods and how they reduce erosion.

Contour plowing → slows water runoff

Windbreaks → block wind

Perennial crops → protect soil year-round

Terracing → slows runoff on slopes

No-till → reduces soil disturbance

Strip cropping → alternates crops to reduce erosion

How do crop rotation, green manure, and limestone increase soil fertility?

Crop rotation → replenishes nutrients, reduces pests

Green manure → adds organic matter and nutrients

Limestone → balances acidic soil pH

What are two things precipitation can do when it hits the ground?

Infiltrate into soil or run off into streams/rivers.