APES Final Review agriculture and aquaculture.pptx

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Agriculture & Aquaculture

APES Final Review

Where our food comes from…


Croplands (77%)


Rangelands, pastures & feedlots (29%)


Aquaculture (7%)




There are 50,000 plant species that we can eat, yet 14 supply
90% of the worlds calories!!!


Food Sustainability


14 varieties of plants


2/3 of the world survives primarily on corn, wheat & rice alone


Small number of species provide for meat & fish


This all leads to food specialization


Disease


Environmental degradation


Climate change


Industrialized Agriculture


Heavy machinery


Goal is to produce more food per area of land


Characteristics include high fertilizer use, pesticide use,
irrigation, genetic engineering, factory
-
like conditions


Monocultures


High resource use

Case Study: Industrialized Food
Production in the United States


Industrialized agriculture uses about 17% of all commercial
energy in the U.S. and food travels an average 2,400
kilometers from farm to plate.

Figure 13
-
7

Traditional Agriculture


Labor
-

intensive


Polyculture


Usually lower resource use


Can have a higher output than Industrialized


Less susceptibility to changes


Traditional Agriculture: Low Input
Polyculture


Many farmers in developing countries use low
-
input agriculture to
grow a variety of crops on each plot of land (interplanting) through:


Polyvarietal cultivation
: planting several genetic varieties.


Intercropping
: two or more different crops grown at the same time in a
plot.


Agroforestry
: crops and trees are grown together.


Polyculture
: different plants are planted together.


SUSTAINABLE AGRICULTURE THROUGH
SOIL CONSERVATION


Modern farm machinery can plant crops without disturbing soil
(no
-
till and minimum tillage.


Conservation
-
tillage farming:


Increases crop yield.


Raises soil carbon content.


Lowers water use.


Lowers pesticides.


Uses less tractor fuel.


Contour Farming


sloping your growing
crops, etc.



You run terraces parallel to the ground to stop
soil from running down a steep slope. Plowing
and planting crops in rows across, rather than up
and down, the sloped contour of the land.

Terracing



(what you
use for contour farming.)
Dirt goes up to hold the
dirt in place. Broad,
nearly level terraces that
run across the land
contour. Helps to retain
water for crops at each
level and reduce soil
erosion by controlling
runoff.


SUSTAINABLE AGRICULTURE THROUGH
SOIL CONSERVATION


Terracing, contour planting,
strip cropping, alley
cropping, and windbreaks can
reduce soil erosion.

Figure 13
-
16


Strip Cropping



a row crop such as corn
alternates in strips with another crop that
completely covers the soil, reducing
erosion. It catches and reduces water
runoff and helps prevent the spread of pests
and plant diseases.

Cover Cropping (alley cropping)



several crops
are planted together in strips or alleys between trees
and shrubs that can provide shade (which reduces
water loss by evaporation) and helps to retain and
slowly release soil moisture.


Irrigation Techniques



Conventional center
-
pivot irrigation
-

allows 80% of the
water input to reach crops


Gravity
-
flow irrigation
-

Valves that send water down
irrigation ditches.


Drip irrigation
-

Can raise water efficiency to 90
-
95% and
reduce water use by 37
-
70%.


Floodplain irrigation
-

allowing the natural floods to irrigate
the crops. Soils in flood zones tend to be nutrient rich and
fertile.

The Green Revolution


Increased food production using industrialized crop
production (heavy machinery)


Steps of the Green Revolution


1. Plant monocultures of high yield crops (wheat, corn, rice).
Often genetically modified.


2. Use high amounts of fertilizers and pesticides to increase
yield


3. Increase the number of crops grown per year


Meat consumption on the rise


Effects:


More densely packed feedlots


High use of grain and or fish meal


Increased need of grain can lead to
dependance

on other
countries


Fig. 13
-
21, p. 289

Trade
-
Offs

Animal Feedlots

Advantages

Disadvantages

Increased meat
production

Need large inputs
of grain, fish
meal, water, and
fossil fuels

Higher profits

Concentrate
animal wastes
that can pollute
water

Less land use

Reduced overgrazing

Reduced soil
erosion

Antibiotics can
increase genetic
resistance to
microbes in
humans

Help protect
biodiversity

PRODUCING MORE MEAT


Efficiency of converting grain into animal protein.


Figure 13
-
22

Harmful Environmental Impacts of
Agriculture


Erosion


Degradation of soil


Water depletion


Water pollution


Greenhouse gasses


Air pollution


Biodiversity loss



**according to the EPA, agriculture is responsible for 75% of water
quality issues in US rivers & streams

Higher use of Biofuel


Biofuel is a renewable energy alternative


However, using too much biofuel aggravates the problems
brought on by agriculture.


Are we replacing one problem with another?



Aquaculture


Raising fish in ponds and underwater cages (43%)


Helps with over
-
fishing


Decrease contamination (ex. Mercury)

Fig. 13
-
24, p. 292

Trade
-
Offs

Aquaculture

Advantages

Disadvantages

High efficiency

Needs large inputs
of land, feed, and
water

High yield in
small volume
of water

Large waste
output

Destroys
mangrove forests
and estuaries

Can reduce
overharvesting
of conventional
fisheries

Uses grain to feed
some species

Low fuel use

Dense populations
vulnerable to
disease

Tanks too
contaminated to
use after about 5
years

High profits

Profits not tied
to price of oil

Fishing

Purse Seines


A large purse
-
like net is put into the ocean and is then closed
like a drawstring purse to trap the fish.


Tuna is a fish typically caught in purse seines


Dolphins are a by
-
catch of purse seines

Long
-
line fishing


Lines are put out that can be up to 80 miles long w/
thousands of baited hooks on them. These are left out free
-
floating for days and then the boat comes back and picks
them up.


Pilot whales, dolphins, sea turtles, and birds are by
-
catch of
this technique.

Drift
-
net fishing


Each net hangs as much as 50 feet below the surface and up to 34 miles
long.


Anything that comes into contact w/ these nearly invisible nets are
entangled.


This leads to overfishing


Many unwanted fish and marine mammals, turtles and seabirds are
caught.