ESS Soil and Food Quiz

What are the four main components of soil?

Soil is composed of:

• Inorganic matter (mineral particles from weathered rock)
• Organic matter (decomposed plant and animal remains, humus)
• Water (soil solution)
• Air (gases in soil pores)

Explain the vital role of soil within environmental systems and its connection to food production.

Soil is crucial for:

• Plant growth: Provides anchorage, water, and essential nutrients for crops.
• Water regulation: Filters and stores water, preventing runoff and making it available for plants.
• Nutrient cycling: Decomposers in soil break down organic matter, releasing nutrients vital for plant uptake and agricultural productivity.
• Habitat: Supports a diverse community of organisms (bacteria, fungi, insects, worms) that contribute to soil health and fertility.
• Climate regulation: Stores significant amounts of carbon, which impacts greenhouse gas levels and global climate.

Using a diagram as a reference, explain the key inputs to a soil system relevant to food production.

When considering a soil system diagram for food production, key inputs include:

• Organic Matter: Dead plant and animal material, manure, compost—vital for soil structure, water retention, and nutrient supply.
• Inorganic Nutrients: Derived from weathered parent material and applied fertilizers (e.g., nitrogen, phosphorus, potassium) essential for plant growth.
• Water: Precipitation (rain, snow) and irrigation—critical for nutrient transport, plant uptake, and biological activity.
• Air: Atmospheric gases like oxygen (for root respiration and decomposition) and nitrogen (for nitrogen-fixing bacteria).
• Solar Energy: Indirectly drives photosynthesis in plants, which contributes organic matter to the soil upon decomposition.

Using a diagram as a reference, explain the key outputs from a soil system, especially concerning food systems.

From a soil system diagram related to food production, key outputs include:

• Crop Yield/Biomass: The harvested food, fiber, or fuel produced by plants growing in the soil.
• Water Loss: Through evaporation from the soil surface, transpiration by plants (evapotranspiration), surface runoff, and deep percolation (leaching into groundwater).
• Nutrient Loss: Via leaching (dissolved nutrients moving downwards), erosion (soil particles with attached nutrients carried away by wind or water), and gaseous losses (e.g., denitrification of nitrogen).
• Gases: Carbon dioxide (from respiration by roots and organisms), methane, and nitrous oxide, important greenhouse gases.
• Erosion: The physical removal of topsoil by wind or water, leading to a loss of fertile soil.

Provide an example of how specific human activities can either positively or negatively impact soil fertility in a food production system.

• Positive Impact Example: Crop Rotation
  • Activity: Farmers rotate different crops (e.g., legumes followed by cereals) in the same field.
  • Impact: Legumes fix atmospheric nitrogen, naturally enriching the soil. Crop rotation also helps break pest and disease cycles, improves soil structure, and reduces the need for synthetic fertilizers.
• Negative Impact Example: Monoculture with Excessive Tillage
  • Activity: Continuously growing the same crop year after year with intensive plowing.
  • Impact: Depletes specific nutrients, reduces soil organic matter, destroys soil structure, and increases susceptibility to erosion and pests, ultimately decreasing long-term soil fertility and productivity.

Define 'soil degradation' and give two examples relevant to environmental systems and societies, particularly concerning food security.

Soil degradation is the decline in soil quality and productivity, reducing its capacity to provide ecosystem services and support biological production.

• Example 1: Erosion
  • Description: The loss of topsoil due to wind or water, often exacerbated by deforestation, intensive farming, or overgrazing.
  • Relevance to Food Security: Reduces the depth of fertile soil, removes essential nutrients, and decreases water retention, leading to lower crop yields and increased food insecurity.
• Example 2: Salinization
  • Description: The accumulation of soluble salts in the soil, commonly in arid and semi-arid regions with poor irrigation management (e.g., using salty irrigation water without adequate drainage).
  • Relevance to Food Security: High salt concentrations inhibit plant growth by reducing water uptake and causing toxicity, rendering agricultural