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28 Cards in this Set

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What has been the trend in crop diversity over the past century?

We have lost a lot of genetic diversity in plants. in the US, fruit and vegetable crops have decreased in diversity by 90% in less than one century.

Soil forms slowly and is a complex system. When decomposers break down organic molecules, they contribute a dark, spongy, an organic material to soil composition called?


Erosion usually begins when____.

The vegetation is removed either naturally or by humans

over irrigation in dry areas can cause ____.

A buildup of salt in the soil to the point where it negatively affects plant growth.

What is the idea that one should not undertake new actions until ramifications of the action is well understood?

Precautionary principle

What are effects of over nutrition?

Chronic over nutrition can lead to diabetes and cardiovascular disease.

What is malnutrition?

Occurs in people who consume adequate calories but lack essential nutrients, such as vitamins and minerals.

What is kwashiorkor?

Occurs in people whose diets include ample calories but very low levels of essential amino acids and proteins.

What is under nutrition?

People who regularly lack access to sufficient food calories.

What is marasmus?

Inadequate caloric intake coupled with protein deficiency.

What are some characteristics of traditional agriculture?

- Many crops grown together on small plots of land

- Relies on human and animal power

- Controls pests with natural pesticides and planting of multiple crops

What are some characteristics of industrial agriculture?

- Controls pests with synthetic pesticides

- Heavy use of synthetic fertilizer

- Relies on fossil fuel powered machinery

- Single crops grown on large plots of land

What is organic litter?

This layer consists of plant residue atop the soil surface. on a forest floor, it may be leaves and twigs. in a field, it may be crop residue left after harvest.

What is topsoil?

This layer consists of organic matter, humus, and inorganic minerals. it facilitates plant rooting, has high nutrient content, and holds water.

What is the eluviated layer?

This layer loses minerals and organic matter to the layer beneath it.

What is subsoil?

This layer accumulates minerals and organic matter leached from upper soil layers.

What is Parent material?

This layer forms that base geologic material in a particular location; it is sometimes called bed rock.

What is conservation tillage?

Farming practices that minimize disturbance to soil.

What is inter cropping?

The practice of planting different crops in strategic arrangements within the same field.

What is crop rotation?

Alternating the crops grown on a field from one season to the next.

What are shelter belts?

Rows of trees or other tall plants grown at edges of farm fields in order to slow down winds.

What is contour farming?

Tilling sideways across a hillside to slow water running down the slope.

What is terracing?

Creates level platforms for crops on steep hillsides in order to hold rainwater and reduce soil erosion.

Why is variety in crop plants important for "food security"?

Varieties contain genes that, through conservational breeding, might confer residence to disease.

How does the conservaton reserve program (CRP) try to protect soil for future agriculture?

The CRP pays farmers NOT to grow crops on land that is not very well suited for crop production.

Which of the following statements best describes the benefits of using organic fertilizers, also known as "green manures", such as dead plants?

Organic fertilizers increased humus in soils.

Over time, pesticides become less effective. This is because ____.

Pest can evolve defense against pesticides.

In regards to energy efficiency, aquaculture is ____.

Incredibly energy efficient compared to harvesting fish from open waters.