Transcript An Ecological Perspective (BIOL 346) Talk Five: Sustainable Agriculture

An Ecological Perspective
(BIOL 346)
Talk Five:
Sustainable Agriculture
Sustainable Agriculture
• The practice of farming using principles of ecology, the
study of relationships between organisms and their
environment.
– It has been defined as "an integrated system of plant and animal
production practices having a site-specific application that will
last over the long term:
• Satisfy human food and fiber needs
• Enhance environmental quality and the natural resource base
upon which the agricultural economy depends
• Make the most efficient use of non-renewable
resources and on-farm resources and integrate, where
appropriate, natural biological cycles and controls
• Sustain the economic viability of farm operations
• Enhance the quality of life for farmers and society as a
whole.
Sustainable agriculture integrates
three main goals
• Environmental health
• Economic profitability
• Social and economic
equity.
Environmental health
• Sustainable Agriculture refers
to agricultural production that
can be maintained without
harming the environment.
• Environmentally Sustainable
Agriculture should be:
– Bearable
– Equitable
– viable for the farmer
• AND - produce the best
quality food for the
consumer, nurture the
environment & preserve
energy.
Economic profitability
• Ecological economics is:
– the interdependence of
‘human economies and natural
ecosystems’.
• It treats the economy and
society as a subsystem of
the ecosystem:
– with emphasis on preserving
natural capital
• recognizes
– That social and economic
systems cannot exist
independently from the
environment.
Social and economic equity
• There is a natural market
premium
• If successful
– Equity will be recognized by
the farmer as beneficial for
this commitment to quality
food output.
• In addition farmer may get
– Government favorable
interest rate financial
incentives and solution
support.
Sustainable agriculture
• Sustainable agriculture in the United States was addressed
by the 1990 farm bill.
• More recently, as consumer and retail demand for
sustainable products has risen, organizations such as Food
Alliance and Protected Harvest have started to provide
measurement standards and certification programs for what
constitutes a sustainable grown crop
What is Sustainable
Agriculture?
• Agriculture has changed
dramatically, especially since the
end of World War II.
• Food and fiber productivity
soared due to new technologies,
mechanization, increased
chemical use, specialization and
government policies that favored
maximizing production.
• These changes allowed fewer
farmers with reduced labor
demands to produce the majority
of the food and fiber in the U.S.
What is Sustainable
Agriculture?
• Has had major social and
ecological impacts, which have
drawn intense praise and equally
intense criticism.
• In fact, many regions of the
world peaked in food production
in the period 1980 to 1995
• Are presently in decline, since
desertification and critical
water supplies have become
limiting factors in a number of
world regions.
What is Sustainable
Agriculture?
• Although these changes have had many positive
effects and reduced many risks in farming, there
have also been significant costs.
•
•
•
•
•
•
Prominent among these are:
Topsoil depletion,
groundwater contamination
decline of family farms,
continued neglect of the living and working
conditions for farm laborers,
increasing costs of production
disintegration of economic and social conditions in
rural communities.
What is Sustainable
Agriculture?
• A growing movement has emerged during the past
two decades to question the role of the agricultural
establishment in promoting practices that
contribute to these social problems.
• Today this movement for sustainable agriculture is
garnering increasing support and acceptance within
mainstream agriculture.
• Not only does sustainable agriculture address many
environmental and social concerns, but it offers
innovative and economically viable opportunities for
growers, laborers, consumers, policymakers and
many others in the entire food system.
The Biosphere
• The atmosphere sustains
life and is sustained by life.
• The Gaia hypothesis
– The entire planet is a
living breathing
organism and will
protect itself –
homeostasis of the
whole planet!!!
• The biosphere works in
“cycles”
• Nitrogen
• Carbon
• Water
•
Some greenhouse
emissions related to
agriculture are
embedded in other
sectors
•
fossil fuels to produce
chemical fertilizers and
pesticides
•
Processing
•
Packaging
•
Refrigeration
•
transport of food
•
land conversion from
biodiverse ecosystems to
giant, monoculture food
plantations
Rodale Institute study
• projects that the planet’s 3.5
billion tillable acres could
sequester nearly 40 percent of
current CO2 emissions if they
were converted to “regenerative”
organic agriculture practices
• Remember:
• Via photosynthesis, over 100 billion
metric tons of CO2 and H2O are
converted into cellulose and other
plant products
Many studies have drawn similar
conclusions.
• India
– organic farming research shows increases in carbon
absorption by up to 55 percent (even higher when
agro-forestry is added into the mix), and water holding
capacity is increased by 10 percent.
• California
– study of 20 commercial farms found that organic fields
had 28 percent more carbon in the soil than industrial
farms.
Water cycle
• The resulting water
vapor mixes with the
atmosphere
• At high altitudes where
the air is cold enough it
condenses to form rain
and snow
• Falls back to Earth.
Water Cycle
• Water evaporates
from bodies of fresh
water and the oceans
• Much water is lost
from the leaves of
plants via transpiration.
• Also from respiration
of almost all living
species
Water
• In some areas, sufficient
rainfall is available for crop
growth, but many other
areas require irrigation.
•
For irrigation systems to
be sustainable they require
proper management (to
avoid salinization) and must
not use more water from
their source than is
naturally replenished
taken from an article by Robert Service in Science
Magazine. “Energy demands on water resources”
Indicators for sustainable water
resource development are:
• Internal renewable water resources.
– This is the average annual flow of rivers and groundwater generated
from endogenous precipitation.
• Can be expressed in three different units:
– in absolute terms (km3/yr),
– a measure of the humidity of the country (mm/yr)
– as a function of population (m3/person per yr).
• Global renewable water resources.
– sum of internal renewable water resources and incoming flow
originating outside the country.
– can vary with time if upstream development reduces water
availability at the border.
Indicators for sustainable water
resource development are:
• Dependency ratio.
– This is the proportion of the global renewable water resources
originating outside the country, expressed in percentage.
– It is an expression of the level to which the water resources of a
country depend on neighboring countries.
•
Water withdrawal.
– When expressed in percentage of water resources, it shows the
degree of pressure on water resources.
– A rough estimate shows that if water withdrawal exceeds a quarter
of global renewable water resources of a country, water can be
considered a limiting factor to development.
– Therefore, the pressure on water resources can have a direct
impact on all sectors, from agriculture to environment and fisheries.
The Soil
• The biggest ecosystem on
Earth!
• Animals:
– micro-organisms mix soils as they
form burrows and pores, allowing
moisture and gases to move about.
In the same way, plant roots open
channels in soils.
• Plants:
– deep taproots can penetrate many
meters through the different soil
layers to bring up nutrients from
deeper in the profile.
– fibrous roots that spread out near
the soil surface have roots that are
easily decomposed, adding organic
matter.
The Soil
• Micro-organisms:
– including fungi and bacteria, effect
chemical exchanges between roots
and soil and act as a reserve of
nutrients.
•
Humans:
– impact soil formation by removing
vegetation cover with erosion as the
result.
– Also mix the different soil layers,
restarting the soil formation
process as less weathered material
is mixed with the more developed
upper layers.
Soil Erosion
• Fast becoming one of the worlds greatest problems. It is
estimated that more than a thousand million tonnes of
southern Africa's soil are eroded every year.
– Experts predict that crop yields will be halved within thirty to
fifty years if erosion continues at present rates.
• Not unique to Africa but is occurring worldwide.
– The phenomenon is being called Peak Soil as present large scale
factory farming techniques are jeopardizing humanity's ability to
grow food in the present and in the future.
• Without efforts to improve soil management practices, the
availability of arable soil will become increasingly
problematic.
Soil Management techniques
• No-till farming
– soil is left intact and crop residue is left on the field.
– soil layers, conserving organisms and layers in their
natural state.
• Keyline design
– maximizes beneficial use of water resources of a piece of
land.
– refers to a specific topographic feature linked to water
flow
• Growing wind breaks to hold the soil
– Planting trees and hedges
– Prevent wind from blowing away top soil
Soil Management techniques
• Incorporating organic matter back into fields
– Composting! Puts Carbon, Nitrogen, Oxygen, Water and
microbes back into the soil!!! Can also add Urine –honest!!
• Stop using chemical fertilizers (contain salt)
– Remember Algal Blooms? Also, the salt kills natural
micro-organisms in soil – contaminates water!!!!!
• Protecting soil from water runoff
– Careful placement of rocks and trees.
• Soil Steaming
– sterilize soil with steam in open fields or greenhouses
– Destroys pathogens
– Destroys weeds, but dead plant material is left in soil as
compost
Nitrogen in the environment
• Present in many forms
• 78% of atmosphere is N2
– Most of this is NOT
available to living organisms
• Getting N2 for the atmosphere
requires breaking the triple
bond between N2 gas to
produce:
• Ammonia (NH3)
• Nitrate (NO3-)
• So, N2 has to be fixed from the
atmosphere so plants can use it
Nitrogen in the environment
• This occurs naturally
by:-Lightning:
– 8%: splits H2O: the free O
and H attack N2 – forms
HNO3 (nitric acid) which fall
to ground with rain
• Photochemical
reactions:
– 2%: photochemical reactions
between NO gas and O3 to
give HNO3
• Nitrogen fixation:
– 90%: biological – bacteria fix
N2 to ammonium (NH4+)
Nitrogen in the environment
• Once fixed in ammonium or
nitrate :– N2 enters biochemical cycle
– Passes through several
organic or inorganic forms
before it returns to molecular
nitrogen
– The ammonium (NH4+) and
nitrate (NO3-) ions generated
via fixation are the object of
fierce competition between
plants and microorganisms
– Plants have developed ways to
get these from the soil as
How do plants get their nitrogen?
• Some plant species are
Legumes.
• Legumes seedlings germinate
without any association to
rhizobia
– Under nitrogen limiting
conditions, the plant and
the bacteria seek each
other out by an elaborate
exchange of signals
• The first stage of the
association is the migration of
the bacteria through the soil
towards the host plant
How do plants get their nitrogen?
• Nodule formation results a
finely tuned interaction
between the bacteria and the
host plant
– Involves the recognition of
specific signals between
the symbiotic bacteria and
the host plant
• The bacteria forms NH3 which
can be used directly by the
plant
• The plant gives the bacteria
organic nutrients.
Bottom line
• Grow crops which are
best suited to local
environment
• Have a plentiful, and
renewable local water
supply
• Protect the soil
• Good crop management
techniques
Good crop management techniques
• Grow a variety of crops.
– spreads economic risk and are
less susceptible to the radical
price fluctuations associated
with changes in supply and
demand.
• Crop rotation
– used to suppress weeds,
pathogens and insect pests.
Good crop management techniques
• Cover crops
– stabilizing effects by holding soil
and nutrients in place
– conserving soil moisture with
mowed or standing dead mulches,
increasing the water infiltration
rate and soil water holding
capacity.
– The use of vineyards can buffer
the system against pest
infestations by increasing
beneficial arthropod populations
and can therefore reduce the
need for chemical inputs.
Bottom line
• Low cost and effective
local storage of food
stuffs
• Low environmental
impact transport
system
• Local market and a
steady and growing
customer base.
So what about backyard
Agricultural Sustainability?
• Grow only crops which mature within the local growing
season.
• Only grow crops selections which will work together in such
a limited space.
• Think about nutrient needs.
• Think about water demands.
• Think about long time storage of successful crops.
Water barrel
• Free (clean) water!!!!!!!
• Rain barrel kit
– www.earthminded.com
– Trash can
– $40.00!!!
• Set up next to garden. Fills up
fast!
– Melting snow will also fill it up.
– Can connect many together.
• Consider county, city, and
state laws!
Composting
• Turning kitchen waste into
natural fertilizer
• Any container will work
– Need air holes
•
Can buy bacteria cultures to add
to container.
– Can add worms to increase
efficiently
• When setting up, layer soil and
kitchen waste.
– Takes approx. one year to get
going from scratch.
Wood ash
• In addition to composting,
can use wood ash from a log
burning fireplace.
• Ash is full of the essential
nutrients required for plant
growth and development.
• Even contains a higher % of
these nutrients than
commercially available
growth supplements.
• Cheap, natural, and fantastic
for the environment and soil
health
Component
Normal agar (ppm)
Ash Agar (ppm)
Arsenic
<0.1
0.1
Barium
<0.1
3.3
0.1
2.2
Calcium
37.9
1409.9
Chlorine
2.1
2.1
Chromium
<0.1
0.1
Cobalt
0.1
0.1
Copper
0.1
2.2
Iron
0.5
27.4
Lead
0.1
0.2
Lithium
<0.1
0.2
Magnesium
11.6
107.6
Manganese
0.2
3.8
Molybdenum
<0.1
0.1
Nitrogen
21.5
21.5
Phosphorus
3.6
109.4
Potassium
35.6
552.1
Sodium
83.7
90.7
Sulfur
268.3
335.8
Tin
0.1
0.1
Zinc
0.1
1.1
Boron
Canning
• So, you grew hundreds of tomatoes.
What to do with them?
• Great preservation technique.
– Allows you to store food stuffs
outside of the growing season
– Can use them for cooking for the rest
of the year
– Better than just freezing food stuffs
• Can store ANYTHING by this
method.
• Not a new technology, just a (mostly)
forgotten one, which is making a
comeback.
Final Summary
• Sustainable Agriculture is:
– The practice of farming using principles of ecology, the study of
relationships between organisms and their environment.
– refers to agricultural production that can be maintained without
harming the environment.
• Not only does it address many environmental and social
concerns, but it:
–
–
–
–
–
offers innovative and economically viable opportunities for:
growers
Laborers
Consumers
policymakers.
The End!
Any Questions?