SCSC 105 exam 2

IDENTIFY THE TWO MAIN CROPS DISCUSSED IN THE DOCUMENTARY,

WHAT PESTS THREATENED THEM, AND WHERE WERE THEY GROWN.

Papayas in Hawaii and Bananas in Africa

What are the five components of an ecosystem?

Food Chains

Diversity

Competitive Exclusivity

Plant Succession

Nutrient Cycles

Name 3 important functions that ecosystems provide.

Climate Regulation, Water Regulation, Nutrient Cycling

Define agroecosystem

Ecosystems modified to produce, food, fiber, and shelter

Compare nutrient cycling in agroecosystems and natural ecosystems.

Natural Ecosystem: Nutrient Cycles are in balance.

Agroecosystems: Nutrient Cycles are altered.

What are the two plant available forms of nitrogen?

Nitrate and Ammonium

Describe the differences and/or similarities of natural ecosystems

compared to agroecosystems in terms of diversity, inputs,management,

breeding, and nutrient loss.

LOOK AT PIC IN NOTES

What are the TWO risks associated with simplified agroecosystems?

Give an example of a simplified agroecosystem from history.

Limited Plant Diversity,

Problems Become Magnified,

Example: Irish Potato Famine

What are three important functions served by soils?

Anchor plants,

Storage of water and nutrients for plant uptake,

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.

Entisol

Inceptisol

Vertisol

Aridisol

Mollisols

Alfisol

Ultisols

What is soil organic matter?

portion of the soil that includes animal and plant residues in various stages of decomposition

What are the five different functions of soil organic matter?

Carbon Sequestration,

Nutrient source,

Soil aggregation and structure,

Water storage,

Chemical sequestration

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

material?

Decreases

What are the three soil particle sizes?

Sand, Silt, Clay

Gravitational Water

Water drains readily through the soil

Field Capacity

Water is held in the pore spaced and is readily available to plants

Permanent wilting point

water is held tightly by soil particles and is not available to plants.

What is soil tilth and what does it determine?

Physical condition of the soil as related to plant growth. Determines ease of tillage, root penetration, aeration, water infiltration/drainage

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

A measurement of the amount of volume change that can occur when a soil wets and dries. Must be considered in structural or engineering project plans.

Compare and contrast soil particle size (sand, silt, clay)

for water holding capacity, drainage,

CEC, ability to store plant nutrients, shrink-swell potential,

and ease of cultivation.

VIEW IMAGE

What is CEC? What does it measure?

Cation Exchange Capacity. Measures the amount of exchangeable cations a soil can sustain.

How does pH affect nutrient availability and soil organisms?

Soil pH of 5 can limit Phosphorus availability to plants. Low soil pH can cause toxic levels of available nutrients.

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

Dry Regions because evaporation exceeds the rate of leaching.

List the 17 essential elements needed for plant growth.

Element NAME and SYMBOL

Carbon

Hydrogen

Oxygen

Nitrogen

Phosphorus

Potassium

Calcium

Magnesium

Sulfur

Iron

Manganese

Copper

Zinc

Boron

Molybdenum

Chlorine

Nickel

What is the best way to determine nutrient availability in a specific soil?

Briefly describe how to collect a soil sample.

Soil testing

Know the phrase

Don't guess, soil test

What are the differences between organic and inorganic fertilizers?

Organic: Derived from living matter. Contains Carbon

Inorganic: Synthetic or mined elements. No Carbon

List and describe the 3 types of organic fertilizers.

Animal Manures, Compost,

Green Manures

What is fertilizer analysis or grade?

•Where is it displayed? Why is it displayed? How is it displayed?

(hint-ratio)

Amount of nutrients contained in a commercial fertilizer. Must be displayed on the label for consumer protection and include the N-P-K ratio (20-10-5).

Broadcast

applied evenly across an entire area

Injection

water soluble liquids placed under soil surface near roots

Banding

applied at planting within 2" of the row

Popup Fertilizer

placed in the seedbed with the seed

Side-dressing

placed alongside the row

Fertigation

injecting the fertilizer in the irrigation of water

List 6 best nutrient management practices.

Test Soil Regularly

Test Manure before application

Time fertilizer and manure application to crop needs

Use the most efficient method for fertilizer application

Combine nutrient management with soil conservation management

Incorporate green manures, cover crops, and perennials into rotation

What is soil erosion

Accelerated loss of soil through the action of wind or water.

Four ways to reduce soil erosion

Crop Rotations

Contour Stripping

Conservation Tillage

Conservation Reserve Program (CPR)

What is a weed?

A plant growing where it is not wanted.

What are the five methods for weed control?

Prevention

Cultural practices

Biological control

Mechanical or manual control

Chemical control

5 characteristics of weeds that allow them to thrive?

Large seed production

Long seed dormancy

Seed Dispersal

Vegetative reproduction

They can grow anywhere

Define Critical Weed Free Period.

When does it occur in the growing season?

Window of time in the growing season that weeds cause the largest reduction in yield, and must be controlled. 4-6 weeks after crop emergence.