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July, 2007
Source:
Renewable Agriculture and Food Systems (2007), 22: 86-108
Cambridge University Press
doi:10.1017/S1742170507001640
Published online by Cambridge University Press 04Jul2007
Organic agriculture and the global
food supply
Catherine Badgleya1, Jeremy Moghtadera2a3, Eileen Quinteroa2,
Emily Zakema4, M. Jahi Chappella5, Katia Avilés-Vázqueza2,
Andrea Samulona2 and Ivette
Perfectoa2
a1 Museum of Palaeontology, University of Michigan, Ann Arbor,
MI 48109, USA.
a2 School of Natural Resources and Environment, University of
Michigan, Ann Arbor, MI 48109 USA.
a3 Department of Horticulture, Michigan State University, East
Lansing, MI 48824, USA.
a4 School of Art and Design, University of Michigan, Ann Arbor,
MI 48109, USA.
a5 Department of Ecology and Evolutionary Biology, University of
Michigan, Ann Arbor, MI 48109, USA.
ABSTRACT
The principal objections to the proposition that organic
agriculture can contribute significantly to the global food
supply are low yields and insufficient quantities of organically
acceptable fertilizers. We evaluated the universality of both
claims. For the first claim, we compared yields of organic
versus conventional or low-intensive food production for a
global dataset of 293 examples and estimated the average yield
ratio (organic:non-organic) of different food categories for the
developed and the developing world. For most food categories,
the average yield ratio was slightly <1.0 for studies in the
developed world and >1.0 for studies in the developing world.
With the average yield ratios, we modeled the global food supply
that could be grown organically on the current agricultural land
base. Model estimates indicate that organic methods could
produce enough food on a global per capita basis to sustain the
current human population, and potentially an even larger
population, without increasing the agricultural land base. We
also evaluated the amount of nitrogen potentially available from
fixation by leguminous cover crops used as fertilizer. Data from
temperate and tropical agroecosystems suggest that leguminous
cover crops could fix enough nitrogen to replace the amount of
synthetic fertilizer currently in use. These results indicate
that organic agriculture has the potential to contribute quite
substantially to the global food supply, while reducing the
detrimental environmental impacts of conventional agriculture.
Evaluation and review of this paper have raised important issues
about crop rotations under organic versus conventional
agriculture and the reliability of grey-literature sources. An
ongoing dialogue on these subjects can be found in the Forum
editorial of this issue.
(Accepted June 09 2006)
RELATED NEWS RELEASE
Ann Arbor, Michigan
Source:
University of Michigan
Organic farming can feed the world, University of Michigan
study shows
Organic farming can yield up to three times as much food on
individual farms in developing countries, as low-intensive
methods on the same land—according to new findings which refute
the long-standing claim that organic farming methods cannot
produce enough food to feed the global population.
Researchers from the University of Michigan (U-M) found that in
developed countries, yields were almost equal on organic and
conventional farms. In developing countries, food production
could double or triple using organic methods, said Ivette
Perfecto, professor at U-M's School of Natural Resources and
Environment, and one the study's principal investigators.
Catherine Badgley, research scientist in the Museum of
Paleontology, is a co-author of the paper along with several
current and former graduate and undergraduate students from U-M.
"My hope is that we can finally put a nail in the coffin of the
idea that you can’t produce enough food through organic
agriculture," Perfecto said.
In addition to equal or greater yields, the authors found that
those yields could be accomplished using existing quantities of
organic fertilizers, without putting more farmland into
production.
The idea to undertake an exhaustive review of existing data
about yields and nitrogen availability was fueled in a
roundabout way, when Perfecto and Badgley were teaching a class
about the global food system and visiting farms in Southern
Michigan.
"We were struck by how much food the organic farmers would
produce," Perfecto said. The researchers set about compiling
data from published literature to investigate the two chief
objections to organic farming: low yields and lack of
organically acceptable nitrogen sources.
Their findings refute those key arguments, Perfecto said, and
confirm that organic farming is less environmentally harmful yet
can potentially produce more than enough food. This is
especially good news for developing countries, where it’s
sometimes impossible to deliver food from outside, so farmers
must supply their own. Yields in developing countries could
increase dramatically by switching to organic farming, Perfecto
said.
While that seems counterintuitive, it makes sense because in
developing countries, many farmers still do not have the access
to the expensive fertilizers and pesticides that farmers use in
developed countries to produce those high yields, she said.
After comparing yields of organic and non-organic farms, the
researchers looked at nitrogen availability. To do so, they
multiplied the current farm land area by the average amount of
nitrogen available for production crops if so-called "green
manures" were planted between growing seasons. Green manures are
cover crops which are plowed into the soil to provide natural
soil amendments. They found that planting green manures between
growing seasons provided enough nitrogen to replace synthetic
fertilizers.
Organic farming is important because conventional
agriculture—which involves high-yielding plants, mechanized
tillage, synthetic fertilizers and biocides—is so detrimental to
the environment, Perfecto said. For instance, fertilizer runoff
from conventional agriculture is the chief culprit in creating
dead zones—low oxygen areas where marine life cannot survive.
Proponents of organic farming argue that conventional farming
also causes soil erosion, greenhouse gas emission, increased
pest resistance and loss of biodiversity.
For their analysis, researchers defined the term organic as:
practices referred to as sustainable or ecological; that utilize
non-synthetic nutrient cycling processes; that exclude or rarely
use synthetic pesticides; and sustain or regenerate the soil
quality.
Perfecto said the idea that people would go hungry if farming
went organic is "ridiculous."
"Corporate interest in agriculture and the way agriculture
research has been conducted in land grant institutions, with a
lot of influence by the chemical companies and pesticide
companies as well as fertilizer companies—all have been playing
an important role in convincing the public that you need to have
these inputs to produce food," she said. |
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