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."
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