SCSC exam 2

Identify the two main crops discussed in the documentary, what pests threatened them, and where were they grown.

• Papaya — threatened by Ringspot virus — grown in Hawaii

• Banana — threatened by banana wilt (bacterial disease) — grown in Uganda

Match the primary individuals featured in the documentary to their qualifications/associations and their position on GMOs.

AGAISNT GMOS

❌ Against GMOs

• Margaret Wille — Hawaii County Council member (M.Ed, JD) — against

• Jeffrey Smith — Institute for Responsible Technology; author/filmmaker — against

• Zen Honeycutt — Founder of Moms Across America (B.A. Fashion Design) — against

• Vani Hari (“Food Babe”) — Author/advocate (B.S. Computer Science) — against

• Charles Benbrook — Former professor, agricultural economist (PhD) — against

• Andrew Kimbrell — Executive Director, Center for Food Safety (JD) — against

Match the primary individuals featured in the documentary to their qualifications/associations and their position on GMOs.

FOR GMOS

• Dennis Gonsalves — Cornell University professor emeritus (PhD Plant Pathology) — for

• Alison Van Eenennaam — UC Davis professor/genetics expert (PhD Genetics) — for

• Pamela Ronald — UC Davis professor (PhD Plant Biology) — for

• Robert Fraley — Monsanto Chief Technical Officer (PhD Microbiology & Biochemistry) — for

Name 3 important functions that ecosystems provide.

• water regulation

• (stores carbon)

• Climate regulation (controls greenhouse gases)

• Nutrient cycling (nitrogen, phosphorus cycles)

Define agroecosystem.

An agroecosystem is an ecosystem that has been modified by humans to produce food, fiber, and/or shelter.

Compare nutrient cycling in agroecosystems and natural ecosystems.

• Natural ecosystems: nutrient cycles are balanced and nutrients are recycled with little loss

• Agroecosystems: nutrient cycles are altered and require inputs (like fertilizers), with higher nutrient loss

What are the two plant available forms of nitrogen?

• Nitrate (NO₃⁻)

• Ammonium (NH₄⁺)

Describe the differences and/or similarities of natural ecosystems compared to agroecosystems in terms of diversity, inputs, management, breeding, and nutrient loss.

• Diversity: Natural = high | Agroecosystems = low (often monocultures)

• Inputs: Natural = none | Agroecosystems = high (fertilizers, pesticides, labor)

• Management: Natural = none | Agroecosystems = highly managed by humans

• Breeding: Natural = natural selection | Agroecosystems = selective breeding

• Nutrient loss: Natural = little to none | Agroecosystems = high loss of soil and nutrients

What are the TWO risks associated with simplified agroecosystems? Give an example of a simplified agroecosystem from history.

• Risk 1: Limited plant diversity

• Risk 2: Problems become magnified (disease, pests, environmental issues spread easily)

Example:

• Irish Potato Famine (potato monoculture → fungus destroyed crops)

• Dust Bowl (soil loss due to poor farming practices)

What are three important soil functions?

• Anchor plants

• Store water and nutrients for plant uptake

• Provide habitat for soil organisms

Name the five soil forming factors.

• Climate

• Organisms

• Relief (topography)

• Parent material

• Time

Name the 7 predominant soil orders in Texas.

• Mollisols

• Vertisols

• Aridisols

• Ultisols

• Alfisols

• Entisols

• Inceptisols

What is soil organic matter?

Soil organic matter is the portion of soil made up of plant and animal residues in various stages of decomposition.

What are the five different functions of soil organic matter?

• Carbon sequestration (helps mitigate climate change)

• Source of nutrients (nitrogen, phosphorus, etc.)

• Improves soil structure (binds particles together)

• Water storage (holds water like a sponge)

• Chemical sequestration (binds toxic chemicals/pesticides)

As C:N ratio increases, what happens to decomposition rates of plant material?

As the C:N ratio increases, decomposition rates decrease (slow down).

What are the three soil particle sizes?

sand, silt, and clay.

Gravitational water:

Water that drains quickly through soil

Field capacity:

Water available for plants

Permanent wilting point:

Water plants cannot use

. What is soil tilth and what does it determine?

Soil tilth is the physical condition of soil for plant growth, and it determines tillage, root growth, aeration, and water movement.

. Define shrink-swell potential in soil. Why is it important?

Shrink-swell potential is how much soil expands when wet and shrinks when dry, and it is important because it affects structures like roads and foundation

sand

Low water holding, fast drainage, low nutrients

silt

Balanced properties, best for plant growth

clay

High water holding, slow drainage, high nutrients, harder to work with

what is CEC

Cation Exchange Capacity (CEC) is how well soil can hold onto nutrients (cations).

How does pH affect nutrient availability and soil organisms?

pH affects how available nutrients are soluble pH 5.5–7.

Where do saline soils typically occur and what is the cause?

They occur in dry regions and are caused by salt buildup from evaporation exceeding leaching.

List the 17 essential elements needed for plant growth (name + symbol).

• C (Carbon), H (Hydrogen), O (Oxygen)

• N (Nitrogen), P (Phosphorus), K (Potassium), S (Sulfur), Ca (Calcium), Mg (Magnesium)

• B (Boron), Mn (Manganese), Ni (Nickel), Cl (Chlorine), Fe (Iron), Cu (Copper), Zn (Zinc), Mo (Molybdenum)

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Know the phrase “Don’t guess, soil test.”

This means you should test soil in a lab to determine nutrient levels instead of guessing.

What is fertilizer analysis or grade? Where is it displayed? Why is it displayed? How is it displayed?

• What it is: The amount of nutrients in a fertilizer

• Where displayed: On the fertilizer label

• Why: For consumer protection and proper use

• How: As a ratio of N–P–K (example: 20–10–5)

List and briefly describe the six different fertilization methods.

Answer:

1. Broadcast: Spread evenly across an area (common for lawns)

2. Injection: Liquid/gas placed below soil near roots

3. Banding: Applied close to the row at planting

4. Pop-up fertilizers: Placed directly with the seed

5. Side-dressing: Applied beside rows during mid-season

6. Fertigation: Fertilizer delivered through irrigation water

What is soil erosion and what are four ways to reduce its effects?

Answer:
Soil erosion is the loss of soil caused by wind or water.

1. Crop rotation: Maintains ground cover year-round

2. Contour stripping: Alternating crop strips to reduce runoff

3. Conservation tillage: Leaves crop residue to protect soil

4. Conservation Reserve Program (CRP): Plants permanent vegetation on land

What is a weed?

A weed is a plant growing where it is not wanted.

What are the five methods for weed control?

1. Prevention – stopping weeds from establishing

2. Cultural practices – crop rotation, planting methods, etc.

3. Biological control – using organisms (insects, bacteria, animals)

4. Mechanical/manual control – tillage, mowing, hand removal

5. Chemical control – using herbicides

What are the 5 characteristics of weeds that allow them to thrive?

• Large seed production – produce many seeds

• Long seed dormancy – seeds survive for years

• Seed dispersal – spread by wind, water, animals, humans

• Vegetative reproduction – regrow from roots (rhizomes, stolons)

• Ability to grow anywhere

Define Critical Weed Free Period.

The critical weed free period is the time when weeds must be controlled because they cause the greatest reduction in crop yield

When does it occur in the growing season?

It occurs about 4–6 weeks after crop emergence.