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Section C: Organic Agriculture in the Agroecoystem
Projected
Outcomes
- Students will begin to apply ecological
analysis to organic production systems.
- Students will learn about some key organic
practices for both crop and livestock production.
- Students will learn how to get technical
information about organic agriculture.
Background
/ Lessons
Introduction
Organic production. A production system that
is managed in accordance with the Act and regulations
in this part to respond to site-specific conditions
by integrating cultural, biological, and mechanical
practices that foster cycling of resources, promote
ecological balance, and conserve biodiversity.
From the definitions section of the National
Organic Standards, Electronic
Code of Federal Regulations (e-CFR), Title
7: Agriculture, Part
205. Accessed December 2006.
See also expanded
definition by the National
Organic Standards Board
Like natural ecosystems, agro-ecosystems are
characterized by nutrient flows and cycles,
energy flows, and the interactions of living
organisms with each other and the physical
environment. However, agro-ecosystems differ
from natural ecosystems in two key ways:
•
First, we expect them to export particular
biological goods for our use.
•
Second, we deliberately manipulate them to
get them to produce those goods in abundance.
These two special qualities of agro-ecosystems
in turn affect their key ecological processes.
As the definitions above show, organic agriculture
seeks to work with ecosystem processes to achieve
its production goals. Because crops and sites
and farming systems are so variable it is a
major challenge to create organic standards
that meet the ecological goals and are still
workable for farmers.
This section begins with a quick look at the
role of the soil in the organic agro-ecosystem
and then encourages students to think about
the ecology of organic production by posing
four ecological questions.
1) What are the water and nutrient flows in
the system?
2) What are the sources and sinks of pollutants
in the system?
3) What are the interactions of living organisms
in the system?
4) What are the energy flows in the system?
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The
Ground Beneath Our Feet
“Organic and low-input farmers pay
attention to their soils. In one interview
after another,
the first thing farmers talked about was how
they managed soils.”
From The Real
Dirt: Farmers Tell about Organic and Low-Input
Practices in the Northeast, 2nd
edition, edited by Miranda Smith and Elizabeth
Henderson, Northeast Organic Farming Association
and Northeast SARE, Burlington, VT, 1998.
Look
at almost any text about organic farming, and
soil management will be a dominant theme.
All farmers value their soil (though they may
feel forced to abuse it), but organic farmers
are particularly passionate.
One way to look at soils is as a physical medium.
It needs to serve a variety of mechanical functions:
provide a substrate for plant roots to grow
in, allow water to drain so plant roots have
access
to oxygen, but hold on to enough water that
roots have access to water. The soil is also
where
plant nutrients are stored, transferred to
roots, and sometimes lost.
Organic farmers
also think about soils as a living system.
They value the mechanical functions
of
soil, but they look beyond those properties
to biological and ecological services. Organic
standards
seek to build and maintain good soil health,
rather than simply avoiding damaging the
physical structure of the soil.
See Module II, Section C and
the Soil Ecology Powerpoint Presentation (Microsoft
PPT) or
(Adobe PDFMicrosoft PPT) for a brief
introduction to soil biology.
The producer must select and implement
tillage and cultivation practices that maintain
or improve
the physical, chemical, and biological condition
of soil and minimize soil erosion. Section 205.203(a)
of the USDA organic regulations.
Since the 1980s one of the main advances in
protecting agricultural soils has been the development
of minimum-till and no-till systems for growing
crops. No-till systems can significantly reduce
both erosion and fuel consumption associated
with tillage, but they almost always rely on
herbicides for weed control. Because the use
of synthetic herbicides is prohibited in organic
agriculture, organic farmers face special challenges
in trying to control weeds and minimize erosion
at the same time.
However, there are a number of practices organic
farmers use to minimize erosion and improve soil
quality while managing pests, including:
•
conservation tillage (including ridge-till and
zone-till)
•
cover crops
•
conservation of crop residues
•
mulching
•
extended crop rotations including perennial crops
and small grains
•
strip cropping
•
application of compost and manure
These multiple strategies may be at least as
effective as no-till in preventing soil erosion
and improving soil quality. To date there has
been little research directly assessing the impact
of organic agriculture on soil conservation and
quality. The Organic Center and the Agricultural
Research Service have embarked on a two year
study to assess soil quality in organic agriculture http://www.organic-center.org/reportfiles/Soil_Quality_Report.pdf
In addition, some organic farmers are beginning
to experiment with no-till in at least part of
their rotation. For example, one organic dairy
farm in Wisconsin planted no-till soybeans (Jodi,
link to Miller Farm pdf) into a standing rye
cover crop in 2006. The rye was killed when the
planter went over the field, weed control was
good over most of the field, and yield was 44
bushels/acre. This yield is about 15% lower than
the 52 bushels/acre soybean yield from similar
fields on the same farm, using normal tillage
practices. However, the farmers think they can
probably improve yields as they gain experience
with managing organic no-till, and they plan
to increase their no-till soybean acreage in
2007.
Activity
1: Soil building practices
For more information on soil conservation in
organic production see
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Ecological question
1: What are the nutrient and water flows in the
system?
In a sustainable system, nutrients will be recycled
to the extent possible and obtained from renewable
sources.
Organic standards encourage nutrient cycling
and use of nutrients from renewable sources by:
- requiring producers to manage soil fertility
through use of rotations, cover crops,
and the application of plant and animal materials.
Section
205.203(b) of the USDA organic regulations.
- prohibiting use of many fertilizers derived
from non-renewable sources, including synthetic
nitrogen
(anhydrous ammonia, urea) and superphosphate
Most organic farmers in Iowa and Wisconsin rely
primarily on green manure crops, local animal
manure, and compost to replace nutrients lost
by the removal of harvested crops. And good certifiers
will seek to ensure that an organic farm’s
nutrient management plan will emphasize on-site
cycling of nutrients. However, the standards
do allow use of some non-renewable fertilizers,
such as rock phosphates. In addition, plant and
animal-based fertilizers are not necessarily
sustainable. For example, manure can be applied
in such a way that it pollutes. Or materials
such as seaweed could be harvested in an unsustainable
manner for use as fertilizer. Thus, how the certifier
and farmer interpret the requirement to “promote
ecological balance” can influence the sustainability
of nutrient management on organic farms.
Conventional farmers and researchers think about
providing nutrients directly to the plants. Organic
farmers and researchers think of building up
healthy and fertile soils, which will then take
care of the plants. To date, relatively little
research has been done based on the organic paradigm.
One interesting organic paradox is that in established
organic fields, crops often attain higher yields
than would be predicted for conventional systems
based on the same available nitrogen levels.
A number of organic soil amendments and supplements
have
not been tested by university researchers. This
does not necessarily mean these products are
not effective, but marketing claims should be
treated with caution.
Activity 2: How will you feed your
crop?
Organic standards strongly encourage the use
of compost, and they also have strict criteria
for the production of compost. For more information
on compost see the discussion and associated
activities in Module
IV, Section C http://www.cias.wisc.edu/curriculum/modIV/secc/mod_iv_secc.htm#composted
and Cornell’s
Composting in Schools website.
These materials cover composting in general.
Refer to the organic standards in the How will
you feed your crop? worksheet for specific requirements
for organic composting.
For an overview of manure and compost use in
organic agriculture see ATTRA publication Manures
for Organic Crop Production.
Organic standards do not directly address use
and cycling of water. However, organic farmers
often observe that as their soil quality increases
under organic management, the ability of their
fields to absorb rainfall and retain moisture
during droughty conditions increases significantly.
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Ecological question 2: What are the sources
and sinks of pollutants in the system?
(c) The producer must manage
plant and animal materials to maintain or improve
soil organic matter content in a manner that
does not contribute to contamination of crops,
soil, or water by plant nutrients, pathogenic
organisms, heavy metals, or residues of prohibited
substances.
Section 205.203(c) of the USDA organic regulations.
A sustainable system will minimize the amount
of pollutants introduced into the environment.
What is a pollutant? It is a chemical that is
damaging to human health or the environment.
Just as a weed is a “plant out of place,” so
whether something is a pollutant depends in part
on context. For example, soil particles are a
valuable resource in the crop field. However,
if those same soil particles are carried from
the field to a stream or river by erosion, they
become sediment—a pollutant that can severely
damage aquatic communities.
Activity 3: Resource or Pollutant
Although the sources of many agricultural pollutants,
such as synthetic fertilizers and pesticides,
are prohibited in organic agriculture, allowed
inputs can also be pollution sources. For example,
soil or manure turn into pollutants when mismanaged
and displaced. A sink is where the pollutant
winds up. Surface waters, including rivers, lakes,
and the ocean, are a common sink for agricultural
pollutants.
Organic standards are designed to minimize the
risk of pollution, but regulations alone cannot
prevent pollution. Good management is required
to implement the practices appropriately, and
sometimes unpredictable weather can cause even
well-managed agroecosystems to result in some
pollution.
The best-known aspect of organic agriculture
is that it prohibits the use of synthetic pesticides
and fertilizers. What is a synthetic pesticide
or fertilizer? A synthetic product is one that
has been created by some kind of human manipulation
and is not otherwise found in nature.
Are all natural pesticides and fertilizers allowed?
In fact, many natural products are also prohibited.
For example, arsenic occurs naturally and was
historically used as a fungicide, but its use
is prohibited in organic agriculture. The National
List of Allowed and Prohibited Substances sets
forth in general terms the prohibited materials
that cannot be used; those that are allowed;
and restricted materials that may be used in
limited circumstances. However, agricultural
inputs are often sold under brand names that
do not make it easy for farmers to know what
the exact ingredients are. In addition, many
products contain so-called inert ingredients
that they do not have to specify on the label.
In order to help farmers and certifiers identify
which products meet organic standards, the Organic
Materials Review Institute (OMRI), a non-profit
organization, reviews products
on the markets and certifies them as Acceptable
or Restricted, if they can be used in organic
production. Unfortunately, there are more products
on the market than have been reviewed by OMRI,
so there are probably products in the market
that would qualify as organic but are not included
in the OMRI list.
Activity 4: Check it out!
Soil
Management: National Organic Program Regulations
published by ATTRA provides an overview of
practices organic farmers can use to meet
the requirements of Section 205.203 (a) through
(d) of the USDA organic regulations.
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Ecological question 3: What are the interactions
of living organisms in the system?
Sustainable agro-ecosystems will
try to work with species interactions and will
favor species diversity.
Everything in an ecosystem affects other parts
of the ecosystem. Typically, production agriculture
has focused on the negative impacts of organisms
other than the crop. In this worldview, all non-crop
plants are seen as weeds that compete for water,
nutrients, and sunlight, and all non-crop animals
from insects to birds and mammals are seen as
useless at best and crop-destroying pests or
disease carriers at worst.
There is some truth to this outlook. Weeds do
compete with crop plants, and many types of animals
eat parts of the crop and can cause substantial
yield losses. Agro-ecosystems differ from natural
ecosystems in that we require them to export
a good portion of their production for off-site
human consumption. So we cannot afford to give
weeds, crop predators, and diseases a free hand.
On the other hand, it turns out that many non-crop
organisms benefit crop production in a variety
of ways, such as by improving nutrient cycling
and availability to the crop, eating crop pests,
providing habitat for beneficial species, and
reducing disease. Organic practices such as crop
rotation, cover cropping, planting trap crops,
and encouraging beneficial insects use biological
diversity to support the farm
Organic agriculture now goes further and requires
farmers to protect and increase biodiversity
on their farms, even in ways that do not contribute
to crop production. However, implementation
of this requirement is still evolving. The
Wild Farm Alliance has developed guides to
help farmers and certifiers improve biodiversity
at http://www.wildfarmalliance.org/resources/organic_BD.htm.
Recommended practices include
- identifying
critical habitats such as riparian areas
and wetlands, wildlife corridors,
native
grasslands, hedgerows, etc. on the farm
map
- identifying
areas of concern such as invasive species
and erosion
- managing water use to benefit wildlife
as well as crop production
- preserving and restoring
native habitat
- scheduling farming practices to benefit
wildlife (for example, timing haying to allow
ground-nesting
birds to fledge)
- managing predation by non-lethal means such
as use of guard animals
Activity
5: take stock
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Ecological question 4: What are the energy flows
in the system?
In the past two hundred years,
our agriculture has made tremendous gains in
the amount of food produced per hour of human
labor. In large part, these gains have been made
by substituting energy from fossil fuel for energy
from human work. On average in the US it takes
about 2 kcal of fossil fuel to bring 1 kcal of
food energy to harvest (in general grain crops
have a positive energy balance, vegetable crops
are roughly neutral, and meat products have a
negative energy balance).
As we begin to recognize the problems caused
by releasing CO2 into the atmosphere, and as
the cost of fossil fuels begins to rise, agriculture
is faced with the challenge of improving fossil
fuel energy efficiency without unacceptable increases
in labor and cost. To what extent can organic
farming contribute to this challenge?
At present, the standards for organic agriculture
do not address energy use directly. Like conventional
farmers, organic farmers use fossil fuels to
power their tractors and other farm machinery.
However, there is one big difference in energy
use between organic and conventional agriculture:
organic agriculture prohibits the use of synthetic
nitrogen fertilizer, which accounts for roughly
20 to 30 percent of the fossil fuel energy input
for many crops.
There are other differences between organic
and conventional agriculture that have energy
use implications, but it is not clear whether
overall they add up to energy savings for the
organic or conventional system. For example,
organic agriculture does not use synthetic pesticides,
which account for a little over 10 percent of
the fossil fuel energy used to produce conventional
corn. On the other hand, organic farmers often
manage weeds with added cultivation and other
practices that consume fossil fuels, such as
flame weeding.
Like conventional farmers, organic farmers can
reduce their consumption of fossil energy by
•
Recycling nutrients and resources on the farm
•
Minimizing transportation costs by using feed
on-farm or selling to and buying from local sources
•
Choosing energy-efficient equipment and buildings
•
Allowing animals to graze (including strip-grazing
of standing crops) to avoid energy use involved
in harvesting, drying, and storing feed crops.
In fact, if the crop will be used to feed livestock,
consider switching from row crops to pasture.
(See energy data from the Wisconsin Cropping
Systems Trials, especially Table 3.)
•
Using renewable energy sources such as wind,
solar, or biomass-fueled power
More than half
of the energy in our food system is used not
on the farm, but in transportation,
processing, storage and packaging, and home
cooking. Organic agriculture does not offer
any energy efficiencies in this important area.
Sustainable practices for the organic consumer
•
Buy local foods, when possible
• Avoid excess packaging
• Use energy-efficient appliances and techniques when possible and minimize
car travel
• Use renewable energy sources, if possible (solar and wind power)
• Consider eating lower on the food chain or sticking to grass-fed meat
and dairy products. (Most of the food energy contained in grain is used by livestock
to sustain their own life and only a small amount is stored as meat. Thus
it
takes 4 lbs of corn to produce 1 lb of pork and 10 lbs of corn to produce
1 lb of beef) For more information on energy see Impacts
of Organic Farming on the Efficiency of Energy
Use in Agriculture.
Conclusion
Organic standards are designed to promote the
ecological sustainability of agriculture, with
particular emphasis on soil and water quality,
and increasing attention to natural habitat preservation.
The requirements of organic agriculture go far
beyond a prohibition on pesticide use.
There are two agro-ecological issues, however,
that the current organic standards do not
address explicitly: quantity of water use and
energy use. Many organic farms are highly efficient
in both energy and water use, but that is a result
of the farmer's personal values rather than a
requirement of the standards.
As the organic standards continue to evolve,
perhaps these important ecological concerns will
be addressed
more directly.
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