Food and Agriculture ppt

calendargrumpyBiotechnology

Dec 14, 2012 (4 years and 8 months ago)

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Food provides

1. Energy (Calorie = amount of heat required to raise the
temperature of one kilogram of water by one degree at
one atmosphere pressure)

2. Materials to build body (carbon, proteins, minerals,
lipids, etc.)


Humans need a variety of foods to supply their
nutritional needs

Review notes from class on these nutrients:


Carbohydrates


Proteins


Fats


Vitamins


Minerals

The Food Pyramid

is a guide for what we

should eat daily.


Malnutrition


a condition when a person does not
consume enough calories or nutrients to supply the
body’s needs

Marasmus (“wasting away”)


not enough calories and
protein








Kwashiorkor
(“displaced child”)


severe protein
deficiency,

bloated belly,

can cause mental

retardation

Overnutrition


too many calories, results in health
problems including diabetes, heart disease, stroke


How do we supply 6.8 billion people with
enough food?

Agriculture

= practice of
raising crops and livestock for
human use and consumption


Cropland

= land used to
raise plants for human use


Rangeland

or
pasture

= land
used for grazing livestock


Land devoted to agriculture
covers 38% of Earth’s land
surface



Agriculture was invented independently by different cultures


The earliest plant and animal domestication is from the “Fertile
Crescent” of the Middle East


Wheat, barley, rye, peas, lentils, onions, goats, sheep


Traditional agriculture

= biologically powered
agriculture, using human and animal muscle power


Subsistence agriculture
= families produce only
enough food for themselves


Uses animals, irrigation and fertilizer, but not fossil
fuels


Industrialized agriculture

= using large
-
scale
mechanization and fossil fuels to boost yields


Yield = amount of food that can be produced in a certain
area


Also uses pesticides, irrigation and fertilizers


Monocultures

= uniform planting of a single crop


Why might monocultures be a bad idea?


Monoculture =
a large expanse of a single crop


More efficient, increases output


Devastates biodiversity


Susceptible to disease and pests


Narrows human diet: 90% of our food comes from 15 crop
species and 8 livestock species

Armyworms easily defoliate monocultures

The Green Revolution


Dramatically increased per
-
acre
yields


Spread to the developing world
in the 1940s with wheat, rice,
corn


Depended on large amounts of


Synthetic fertilizers


Chemical pesticides


Irrigation


Heavy equipment




Soil is a

thin covering over
most land that is a complex
mixture of eroded rock,
mineral nutrients, decaying
organic matter, water, air,
and billions of living
organisms, most of them
microscopic decomposers

Soil is important because:

1.
It provides most of the
nutrients needed for
plant growth, and
subsequently consumer
growth.

2.
It is the primary filter that
cleanses water as it passes
through.

3.
It is a major component
of the earth’s water
recycling and water
storage processes.

Components of soil

25% air (mostly N and O)

25% water

45% mineral

5% organic matter


Amounts of air and

water vary

Soil is a renewable resource

Formation of soil depends on 5 factors:


1. climate



3. biologic activity


5. time


2. terrain



4. geology


It takes 15 to 100s of years to form one cm of soil!



*Parent material

= the base geologic material of soil

**Bedrock

= the continuous mass of solid rock comprising the Earth’s crust


*

**

Weathering produces soil

Weathering

= the physical,
chemical, or biological
processes that break down
rocks to form soil


Physical (mechanical)


wind and rain


no chemical changes in
the parent material

Chemical


substances chemically
interact with parent
material

Biological


organisms break down
parent material

Soil Horizons: Layers of mature soil

O horizon


organic material, leaf
litter, many organisms live here


A horizon


topsoil layer, zone of
accumulation of organic matter
and nutrients


These top 2 horizons contain:


-

the roots of most plants


-

billions of living things
(bacteria, fungi, earthworms,
insects, etc.)


Soil Horizons: Layers of mature soil

B horizon


subsoil, accumulates iron,
clay, aluminum and organic
compounds that leach down from
above

(leaching: process in which water
seeps down through open spaces or
pores in soil, dissolving minerals
and organic matter and carrying
them to lower layers)


Soil Horizons: Layers of mature soil

C horizon


parent material, contains
large lumps or shelves of rock


R horizon (under C horizon)
-

bedrock


Soil Particles

Three types, based on size:

1.
Sand: 2.0
-
0.05 mm

2.
Silt: 0.05
-
0.002mm

3.
Clay: less than 0.002mm


Relative amounts determine soil
texture



Soil Textural Classification


Soil Permeability

Definition: the rate at which water and air move from upper to
lower soil layers

The more spaces there are between soil particles, the more
permeable it is

Plants need good drainage, but not too much








Plants are like Goldilocks

Sandy soil: This soil is too permeable


water runs right
through

Clay soil: This soil is too impermeable


water can’t get
through

Loam: This soil is just right! (mixture of sand and clay)


Which is which?

Sand on left

Loam in middle

Clay on right

Other soil characteristics that are
important to plants


Nutrient content


nitrogen, phosphorus and
potassium


pH


if soil is too acidic or basic, plants can’t grow

Agriculture and Population Growth

The earth has a carrying capacity for the human
population


we don’t know what it is.

We do not have unlimited land and resources to produce
food for people.















We face food issues as our population
grows:


1. Lack of enough arable land


Graph showing per capita arable land over time:

2. Soil degradation

soil erosion


the dislodging and movement of soil by
wind or water, occurs when vegetation is absent

Erosion increases through: excessive tilling, overgrazing, and
clearing forests

Can result in desertification
-

most prone areas are arid and
semiarid lands





The Dust Bowl


In the late 19
th

and early 20th
centuries, settlers arrived in
Oklahoma, Texas, Kansas, New
Mexico and Colorado


Grew wheat, grazed cattle


Removed vegetation


A drought in the 1930s made
conditions worse


Thousands of farmers left their land
and had to rely on governmental help

Various types of soil erosion

Splash

Sheet

Rill

Gully

We lose 5
-
7 million ha (12
-
17 million acres) of productive
cropland annually


3. Uneven food distribution around the
world

Developing countries: usually faster population growth,
more poverty, less infrastructure to grow and
distribute food


4. Problems with irrigation


Irrigation

= Artificially providing
water to support agriculture


Unproductive regions become
farmland


Waterlogging

= over
-
irrigated soils


Water suffocates roots


Salinization

= the buildup of salts in
surface soil layers


Depletion of ground and surface
waters

5. Loss of biodiversity

When we convert natural habitats to farms, we reduce
natural habitat

We also plant monocultures and use few species for
crops



6. Negative effects of overgrazing


Soil compaction


Non
-
native invasive species invade


Less palatable to livestock


Out compete native vegetation

Ungrazed plot

Grazed plot

7. Pollution from:

Agriculture
-

pesticides, herbicides, fertilizers,

Livestock (on feedlots)


animal waste, excess methane
is a greenhouse gas

Overapplication of Fertilizer


Inorganic fertilizer use has
skyrocketed


Overapplying fertilizer can ruin
the soil and severely pollute
several areas


Runoff causes eutrophication in
nearby water systems


Nitrates leach through soil and
contaminate groundwater


Nitrates can also volatilize
(evaporate) into the air

8. Resistance to pesticides


Some individuals are genetically immune to a pesticide


They survive and pass these genes to their offspring


Pesticides stop being effective


Evolutionary arms race
: chemists increase chemical toxicity to
compete with resistant pests

Solutions to our agriculture issues:



Sustainable Agriculture


Industrial agriculture may seem necessary, but less
-
intensive
agricultural methods may be better in the long run


Sustainable agriculture

= does not deplete soil, pollute water, or
decrease genetic diversity


Protecting soil: crop rotation and
contour farming


Crop Rotation

= alternating the
crops grown field from one season
or year to the next,


Cover crops protect soil when main
crops aren’t planted


Wheat or corn and soybeans


Contour Farming

= plowing
furrows sideways across a hillside,
perpendicular to its slope, to
prevent rills and gullies

Protecting soil: terracing and
intercropping


Terracing

= level platforms
are cut into steep hillsides,
sometimes with raised edges


A “staircase” to contain water


Intercropping

= planting
different types of crops in
alternating bands or other
spatially mixed arrangements


Increases ground cover

Pros and cons of no
-
till farming


Almost half of U.S. farmland
uses no
-
till farming


Benefits: reduced soil erosion,
greater crop yields, enhanced
soils


Negatives: increased use of
herbicides and fertilizers

Biological control


Biological control

(
Biocontrol
) = uses a pest’s
natural predators to control
the pest


Reduces pest populations
without chemicals


Cactus moths control prickly
pear


Bacillus thuringiensis (Bt)

=
soil bacteria that kills many
pests

Salinization prevention


It is easier and cheaper to
prevent salinization than fix it


Do not plant water
-
guzzling
crops in sensitive areas


Irrigate with low
-
salt water


Irrigate efficiently, supplying
only water that the crop
requires


Drip irrigation

targets water
directly to plants

Integrated Pest Management (IPM)


IPM uses multiple techniques to
suppress pests


Biocontrol


Chemicals, when necessary


Population monitoring


Habitat alteration


Crop rotation and transgenic crops


Alternative tillage methods


Mechanical pest removal

Within 4 years of using IPM in Indonesia, rice yields rose 13%, and
$179 million saved by phasing out subsidies

Genetically Modified Organisms
(GMOs)


Genetic engineering =
laboratory manipulation of
genetic material


Genetically modified
organisms

= organisms that
have been genetically
engineered by …


Recombinant DNA

= DNA
created from multiple
organisms


Genetic engineering has both benefits and risks


Benefits of genetic engineering:


Increased nutritional content


Increased agricultural efficiency


Rapid growth


Disease and pest resistance


Negatives of genetic engineering:


Risks are not yet defined or well understood


Protests from environmental activists, small farmers, and
consumer advocates


Some genetically modified foods

Change diet practices


Eat less meat


Eat organic


Eat locally produced foods


Eat diverse foods

Eating animal products has
significant impacts


As wealth and commerce increase, so does consumption of meat,
milk, and eggs


Global meat production has increased fivefold


Per capita meat consumption has doubled

Domestic animal production for food increased from 7.3
billion in 1961 to 20.6 billion in 2000

Energy choices through food choices


90% of energy is lost every time
energy moves from one trophic
level to the next


The lower on the food chain from
which we take our food sources,
the more people the Earth can
support.


Some animals convert grain


into meat more efficiently than
others

Environmental ramifications of eating meat



Land and water are needed to raise food for livestock


Producing eggs and chicken meat requires the least
space and water


Producing beef requires the most

When we choose what to eat, we also choose how we use resources

Organic agriculture


Organic agriculture

= Uses no synthetic fertilizers, insecticides,
fungicides, or herbicides


Relies on biological approaches (composting and biocontrol)


People debate the meaning of the word “organic”


Organic Food Production Act (1990) establishes national standards for
organic products


The USDA issued criteria in 2000 by which food could be labeled organic

Aquaculture


World fish populations are
plummeting


Technology and increased
demand


Aquaculture

= raising
aquatic organisms for food
in a controlled environment


Aquatic species are raised in
open
-
water pens or land
-
based ponds

The benefits and drawbacks of aquaculture


Benefits:


A reliable protein source


Sustainable


Reduces fishing pressure on
overharvested wild fish stocks


Energy efficient


Drawbacks:


Diseases can occur, requiring
expensive antibiotics


Large amounts of waste


Farmed fish may escape and
introduce disease into the wild

Government intervention

The Soil Conservation Service


Started in 1935, the Service works with farmers to develop
conservation plans for farms


Assess the land


Prepare an integrated plan


Work closely with landowners


Implement conservation measures


Conservation districts

= districts operate with federal
direction, authorization, and funding, but are organized
by the states

What can you do?

Eating to Save the Earth: Food Choices for a Healthy Planet
by Linda Riebel and Ken
Jacobsen

As a consumer, you can:


Use locally grown food, or grow your own!


uses less fuel for transportation


(Example: a single fast food meal comes from Texas (meat), Nebraska (corn to feed cow),
Washington (cheese), California (lettuce and tomato), Idaho (wheat for bun and
potatoes), Louisiana (salt), Pennsylvania (ketchup), Ohio (ketchup pouches), Arkansas
(french fry box), Iowa (corn syrup for soft drink))


Buy organic


few or no pesticides or chemicals added


Go vegetarian (or nearly)


use little or no meat, dairy, eggs


Use less processed foods
-

stay close to the food’s natural state


Buy products with less packaging


Branch out and buy unusual products to support diversity


Consider purchasing products that support fair trade


Try not to waste food


Educate yourself and think critically


http://well.blogs.nytimes.com/2007/10/22/five
-
easy
-
ways
-
to
-
go
-
organic/?em&ex=1193544000&en=39941565969220ef&ei=5087%0A