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Researchers at McGill, Univ. of Minnesota call for
combining best of both approaches
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.”
