An organic food market |
ScienceDaily, April 25, 2012
Can organic
agriculture feed the world? Although organic techniques may not be able to do
the job alone, they do have an important role to play in feeding a growing
global population while minimizing environmental damage, according to
researchers at McGill University and the University of Minnesota.
A new study
published in Nature concludes that crop yields from organic farming are
generally lower than from conventional agriculture. That is particularly true
for cereals, which are staples of the human diet -- yet the yield gap is much
less significant for certain crops, and under certain growing conditions,
according to the researchers.
The study, which
represents a comprehensive analysis of the current scientific literature on
organic-to-conventional yield comparisons, aims to shed light on the often
heated debate over organic versus conventional farming. Some people point to
conventional agriculture as a big environmental threat that undercuts
biodiversity and water resources, while releasing greenhouse gases. Others
argue that large-scale organic farming would take up more land and make food
unaffordable for most of the world's poor and hungry.
"To achieve
sustainable food security we will likely need many different techniques --
including organic, conventional, and possible 'hybrid' systems -- to produce
more food at affordable prices, ensure livelihoods to farmers, and reduce the
environmental costs of agriculture," the researchers conclude.
Overall, organic
yields are 25% lower than conventional, the study finds. The difference varies
widely across crop types and species, however. Yields of legumes and perennials
(such as soybeans and fruits), for example, are much closer to those of
conventional crops, according to the study, conducted by doctoral student
Verena Seufert and Geography professor Navin Ramankutty of McGill and Prof.
Jonathan Foley of the University of Minnesota's Institute on the Environment.
What's more, when
best management practices are used for organic crops, overall yields are just
13% lower than conventional levels. "These results suggest that today's
organic systems may nearly rival conventional yields in some cases -- with
particular crop types, growing conditions and management practices -- but often
they do not," the researchers write. Improvements in organic management
techniques, or adoption of organic agriculture under environmental conditions
where it performs best, may help close the yield gap, they indicate.
"Our study
indicates that organically fertilized systems might require higher nitrogen
inputs to achieve high yields as organic nitrogen is less readily available to
crops. In some cases, organic farmers may therefore benefit by making limited
use of chemical fertilizers instead of relying only on manure to supply
nitrogen to their crops," Seufert says. "At the same time, conventional
agriculture can learn from successful organic systems and implement practices
that have shown environmental benefits, such as increased crop diversity and
use of crop residues."
Yields are only
part of a set of economic, social and environmental factors that should be
considered when gauging the benefits of different farming systems, the
researchers note. "Maybe people are asking the wrong question," Prof
Ramankutty says. "Instead of asking if food is organically grown, maybe we
should be asking if it's sustainably grown."
The
results point to a need to get beyond the black-and-white, ideological debates
that often pit advocates of organic and local foods against proponents of
conventional agriculture, Prof. Foley adds. "By combining organic and
conventional practices in a way that maximizes food production and social good
while minimizing adverse environmental impact, we can create a truly
sustainable food system."
Story Source:
The above story is reprinted from materials provided by McGill University, via Newswise.Note: Materials may be edited for content and length. For further information, please contact the source cited above.
Journal Reference:
- Verena Seufert, Navin Ramankutty, Jonathan A. Foley.Comparing the yields of organic and conventional agriculture. Nature, 2012; DOI: 10.1038/nature1106
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