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A middle path to sustainable farming

This story was originally published by Knowable Magazine.

Alfalfa, oats and red clover are soaking up the sunlight in long
narrow plots, breaking up the sea of maize and soybeans that
dominates this landscape in the heart of the US farm belt. The
18-by-85-meter sections are part of an experimental farm in Boone
County, Iowa, where agronomists are testing an alternative approach
to agriculture that just may be part of a greener, more bountiful
farming revolution.

Organic agriculture is often thought of as green and good for
nature. Conventional agriculture, in contrast, is cast as big and
bad. And, yes, conventional agriculture may appear more
environmentally harmful at first glance, with its appetite for
synthetic pesticides and fertilizers, its systems devoted to one or
two massive crops and not a tree or hedge in sight to nurture
wildlife. As typically defined, organic agriculture is free of
synthetic inputs, using only organic material such as manure to
feed the soil. The organic creed calls for caring for that soil and
protecting the organisms within it through methods like planting
cover crops such as red clover that add nitrogen and fight
erosion.

But scientists bent on finding ways to produce more food
globally with as little environmental impact as possible are
finding that organic farming is not as green as it seems. In a
simple contest of local environmental benefits, organic
wins hands down. That doesn’t hold true on a global scale, though,
because organic farming can’t match the high-yield muscle of big
agriculture. A widespread shift to organic would leave billions
hungry, researchers predict, unless farmers put more land to work
by turning now-unfarmed habitats into food-producing fields — doing
more harm than good to natural ecosystems.

Photograph shows a field of red clover growing next to a field of corn in a crop rotation experiment at Iowa State University’s experimental farm in Boone County.

Red clover (foreground) grows alongside corn (background) in a
crop rotation experiment at Iowa State University’s experimental
farm in Boone County.

CREDIT: PAULA R. WESTERMAN

“Organic farming is often seen as synonymous with sustainable
farming, but it is not the Holy Grail of sustainable agriculture,”
says Verena Seufert, an environmental geographer at VU Amsterdam
who studies sustainable food systems. But the strategies being
tested in those fields in Iowa, and similar methods finding their
way onto hundreds of millions of acres of farmland globally, might
just be. In experiments in Europe and across North America,
agronomists are testing hybrid approaches that weave together the
green touch of organic farming with a dash of chemical fertilizer
and pesticide applied only when needed — an approach known as
low-input agriculture. They hope that this cocktail of farming
techniques will steer future farming to a truly sustainable
footing.

This shift toward fusion farming comes at a time of increasing
political interest in greener, more productive agriculture. Heads
of state and governments will meet in September at the United
Nations in New York for a summit to discuss progress toward 17
global sustainability targets
to be met by 2030. Producing more
food with fewer impacts is key to reaching many of these goals,
which include ending hunger and slashing water pollution. That’s
also in line with meeting a separate set of targets that countries
party to the Convention on Biological Diversity are working
toward.

Many experts worry that little progress has been made,
particularly on saving biodiversity. But others are confident that
a greener agricultural revolution is not far off. “It’s optimistic,
but it’s not a pipe dream,” says Jules Pretty, an agroecologist at
the University of Essex in the UK, who studies sustainable
agriculture. “Agriculture could be at a turning point.”

And turn it must, says Andrew Balmford, a conservation scientist
who studies farming’s impacts on biodiversity at the University of
Cambridge in the UK. “Agriculture is by far the biggest threat to
biodiversity, and that will only get worse as we try to feed 10
billion people in the future.”

Graphic shows the number of studies revealing organic farming’s positive, negative or neutral effects on the abundance of organisms like spiders, earthworms, butterflies and plants. Organic farming can be beneficial to biodiversity, especially for creatures like birds, spiders and soil-dwelling insects. The effect is less pronounced for animals like butterflies and uncertain for some animals like beetles, which have shown a mix of negative, positive or no effect, depending on the study.

Many studies show that organic farming is beneficial to
biodiversity, especially for creatures like birds, spiders and some
soil-dwelling insects. The effect is less pronounced for animals
like butterflies. Outcomes for other critters, such as beetles, are
more uncertain, with individual studies showing a breadth of
effects.

Organic aims

Over the next 30 years, agricultural economists estimate, food
production will need to at least double to feed billions of extra
bellies as the global population grows. But the current farming
system cannot carry on as it is without wreaking great damage,
experts conclude. The International Union for Conservation of
Nature, a science-based conservation organization, says that of the 8,500 threatened species it has
studied, agriculture alone imperils 62 percent
, ranging from
the elegant African cheetah to California’s lovable Fresno kangaroo
rat. Fertilizers running off farmland and into rivers and lakes are
fueling toxic algal blooms across the world, suffocating fish and
damaging ecosystems. And agriculture has its hand in around
80 percent of global deforestation.

The organic movement was sparked, in part, from similar
environmental concerns in the early twentieth century. With its
roots in Europe and the US, organic farming grew from the idea that
soils nurtured with compost rather than synthetic fertilizers could
safeguard the soil and biodiversity while producing more nutritious
food. Today, organic produce is a must-have stock on the shelves of
many major Western supermarkets, and organic farming is practiced
in more than 180 countries, on more than 172 million acres of
farmland. Although this is still just 1.4 percent of global
agricultural land, land farmed organically has increased more than
sixfold since 1999 and is rising.

Organic farming could easily spread further and help put more
food on the global dinner table, says John Reganold, an
agroecologist at Washington State University. “In many ways,
organic farming is leading the way towards food security and
sustainability because it is a well-recognized farming system that
is economically successful — and so more farmers want to try it. I
think we owe credit to organic for that,” he says. But he and many
others who have studied the issue say that without a massive change
in diet, organic could never grow enough food globally on existing
farmland despite its demonstrated pluses.

Many studies have shown that organic farming has benefits for
biodiversity on farms. For example, in an assessment comparing organic and conventional
farming
published in Science Advances in 2017, Seufert
reported that organic farms host up to 50 percent more organisms
such as bees and birds than conventional farms. They nurture
greater biodiversity largely because they don’t use synthetic
herbicides and pesticides, allowing plants, insects and other
animals to thrive. Farm workers also benefit from lower pesticide
exposure, Seufert says.

Graphic shows two red circles with petals extending outward. The petals represent different variables affect by organic and conventional farming, such as organism abundance and nitrogen loss. The red circle indicates the point at which organic performance equals that of conventional, petals that extend outside the red circle organic outperforms conventional, and where petals are inside the red circle, organic performs worse. For a variable like low pesticide residues, organic farming has clear benefits over conventional farming. But for a variable like low nitrogen loss, organic farming’s benefit diminishes when output is assessed rather than area.

The benefits of organic farming depend a lot on what is being
measured. For a variable like low pesticide residues, organic
farming has clear benefits over conventional farming, as indicated
by the petal extending beyond the red circle, which demarks where
organic performance equals that of conventional farming. But for a
variable like low nitrogen loss, organic farming’s benefit
diminishes when output is assessed (right) rather than area
(left).

Organic farms also take better care of soil than average
conventional farms, studies show. Enriched with compost from rotted
animal manure or plant matter, organic soils can contain up to 7 percent more
organic matter than their chemically enhanced counterparts
,
according to Matin Qaim, an agricultural economist at the
University of Goettingen in Germany, and colleague Eva-Marie
Meemken, writing in the 2018 Annual Review of Resource
Economics
. Organic matter, rich in diverse microbes, is key to
the health and structure of soil, helping it hold on to water and
reducing erosion.

Qaim and Meemken report that, acre for acre, organic farming
consumes less energy largely because it doesn’t use synthetic
fertilizers. It also releases lower levels of some greenhouse gases
such as carbon dioxide and methane, and leaches fewer polluting
nutrients such as nitrates from fertilizers into rivers and
groundwater. Organic fields are also an experimental ground for
greener farming techniques, such as planting cover crops including
the leguminous hay crop red clover (Trifolium pratense).
Cover crops help suppress weeds and guard against erosion.

Yield is the one crucial feature where organic farming falls
short, Qaim concludes. Organic yields are on average up to 25
percent lower than conventional farming yields. Some crops grow
better than others under organic conditions: Legumes, which fix
nitrogen from the air and thus can meet some of their own nitrogen
needs, tend to produce deficits of just 10 to 15 percent. But
yields of nitrogen-thirsty cereals are 21 percent to 26 percent
lower on organic soils, due to limited nutrient supply as well as
greater susceptibility to pest outbreaks and encroachment by weeds,
Qaim says.

“The facts are not in favor of organic — the observation that
organic yields are lower than in conventional practices cannot be
denied,” he says.

Photograph shows strips of corn growing alongside alfalfa and soybeans in test plots at the USDA’s Agricultural Research Service Farming System project, in Beltsville, Maryland. Different crops grown in the same field at the same time can boost yields and help control weeds and pests.

Different crops grown in the same field at the same time can
boost yields and help control weeds and pests. Here, strips of corn
grow alongside alfalfa and soybeans in test plots at the US
Department of Agriculture’s Agricultural Research Service Farming
System project, in Beltsville, Maryland.

CREDIT: MICHEL CAVIGELLI / USDA-ARS

Small yields add up to a big problem. Switching all the world to
organic would mean turning 24 percent more natural habitats into
agricultural land
 to meet future demands, researchers
calculate. Small yields also drive up greenhouse gas emissions
produced by organic farming because land must stay working rather
than being allowed to regularly go fallow. Organic’s land-use costs
would undo much of the ecological good that organic brings locally,
Qaim says.

Organic advocates, however, question the size of yield gaps
reported in much of the scientific work. The Rodale
Institute
, an organic advocacy and research center in Kutztown,
Pennsylvania, says its own work shows that under certain conditions
organic farming can match or exceed conventional yields. Andrew
Smith, the institute’s chief scientist, acknowledges that organic
yields are overall lower. But he says they have plenty of scope to
grow if greater investment is made in developing crop and animal
breeds better suited to organic’s challenges, and in doing more
research on best practices. Global funding for research on organic
farming is less than 1 percent of that spent on conventional
farming and food, according to a 2017 report from the International Federation of
Organic Agriculture Movements.

Conventional farming’s failures

The researchers who conclude that organic could not feed the
globe’s growing population also recognize that conventional
agriculture can’t carry on as it is, either. So agronomists are
doubling down on the middle road, testing a fusion of techniques
where farmers use green practices topped with synthetic inputs when
necessary. Many of these green techniques, such as planting cover
crops and growing different crops in the same field one year to the
next, were once routinely used in agriculture to manage weeds and
soil health but fell out of favor after World War II when the cost
of synthetic fertilizers and herbicides dropped. These methods are
now making a supercharged comeback in the low-input agriculture
movement.

Studies are starting to show that low-input fusion farming comes
up trumps for both yields and the environment. After an eight-year
experiment ending in 2016, agronomists at the universities of
Minnesota and Iowa State reported promising results from three-crop rotation
systems on a 22-acre experimental farm at Iowa State. The crops
were switched over periods of two, three or four years and assessed
for yield, profit and environmental effects such as soil erosion
and nitrogen leaching into rivers and groundwater.

Graphic shows a bar graph comparing the average yields for alfalfa, corn, oats and soybeans grown in crop rotation experiments and grown without crop rotation. Crop rotation yields are slightly higher than non-crop rotation.

Average yields in the Marsden Farm crop rotation experiments are
higher than that of conventional commercial farms in Boone
county.

In the two-year crop rotation, researchers planted maize and
soybeans in alternating years, but added a mixed crop in the
three-year rotation, planting oats and red clover together for year
three. They planted oats along with a different legume, alfalfa, in
year three of the four-year rotation field, then let the alfalfa
keep growing into the fourth year, after the oats were
harvested.

The team was able to slash the input of synthetic chemicals.
Researchers added fertilizers in the two-year rotation plots at
rates typical of conventional farms, but used substantially less in
the three- and four-year rotation plots: on average 85 percent and
91 percent less synthetic nitrogen (13 and 8 kilograms per hectare
per year, respectively). The researchers added manure to boost
nitrogen but it contained about half the amount of nitrogen that a
full application of synthetic fertilizer supplies. They also added
substantially less herbicide active ingredient to the low-input
maize and soybean crops: 94.8 percent (0.06 kg/ha) and 92.5 percent
(0.12 kg/ha), respectively. Herbicide application did not differ
across the longer and shorter rotations.

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Yields rose as the number of rotations increased and were
unaffected by the lower herbicide use in the longer rotations. On
average, maize yields were 4.5 percent higher and soybean yields 25
percent higher in the three- and four-year rotations compared with
the two-year rotations. The alfalfa and clover steps are key for
this effect, says Matt Liebman, an agronomist at Iowa State and one
of the study’s authors. “You begin to see big changes in nutrient
dynamics because the hay crops like alfalfa and clover take
atmospheric nitrogen and put it into the soil” for the crops that
follow, he says. “So you don’t have to have anywhere near as much
fertilizer.”

Problems with weeds and disease also looked somewhat better.
Despite a lower use of herbicide in the three- and four-year
rotations, weeds intruded equally in the two- and four-year
rotation plots. And soybeans grown in the longer rotations
succumbed less often to soybean sudden death syndrome, a fungal
infection common to the Midwestern farm belt. “The crop rotations
typically result in much more effective management of insect
disease and weed pests with much lower investment in chemical
pesticides because you disrupt the life cycles of many of the pests
that are specialized for particular crops,” Liebman says.

Finally, the low-input, longer rotation strategies also had
environmental benefits. The potential harm to freshwater ecosystems
caused by the herbicide (known as toxicity load) was 99.9 percent lower in the low-input maize plots than
in the conventional maize plots. And though the longer rotations
required more labor, profits for all three rotation systems were
similar overall.

Aerial photograph shows narrow plots of corn, soybeans, oats and alfalfa growing at Iowa State University’s Marsden Farm where agronomists are testing how crop rotations and low levels of synthetic inputs affect yields. The more diverse crop rotations had yields that were equal to or better than the conventional system, despite receiving fewer synthetic inputs like herbicides and fertilizers.

Narrow plots of corn (m), soybeans (sb/s), oats (g), and alfalfa
(a) grow at Iowa State University’s Marsden Farm where agronomists
tested how crop rotations and low levels of synthetic inputs, like
herbicides and fertilizers, affect yields. All three crop rotations
(2-year, 3-year and 4-year) were tested in four replicate blocks
(1, 2, 3, 4). The more diverse crop rotations had yields that were
equal to or better than the conventional system, despite receiving
fewer synthetic inputs.

CREDIT: A. DAVIS ET AL / PLOS
ONE
 2012

Balancing yields and pollution

Other studies in Europe and across the US are reporting similar
results. A meta-analysis of 15 studies done in the US, Canada,
France, Sweden, Switzerland and Norway concluded that yields of
maize grown under low-input conditions were equal to those produced
under conventional conditions, and 24 percent higher than organic
crops. Wheat yields were 12 percent lower than conventional, but 43
percent higher than organic, according to the analysis, published in 2016 in Agronomy Journal.
On average, crops grown under low-input conditions received less
than half the synthetic pesticide applied to conventionally grown
crops and were often cultivated as part of a crop rotation that
included more plant species than in conventional systems.

Agronomist Laure Hossard of the Montpellier campus of the French
National Institute for Agricultural Research, a coauthor of the
meta-analysis, says it’s unclear why wheat yields dropped but maize
yields didn’t under low-input conditions. Perhaps wheat succumbed
more to uncontrolled disease or needed more fertilizer. Still, the
low-input wheat yield losses were small, and the study’s overall
conclusion is that low-input farming can dramatically cut back on
pesticide use without drastically harming yields.

There are some potential downsides to low-input farming, Hossard
says. Money spent on pesticides and fertilizers may not always
compensate for lost income from slightly lower yields. Although
studies have shown that it is possible to cut pesticide use by around 30 percent without
reducing farmers’ income
, these calculations may vary from year
to year as prices for crops and synthetic inputs fluctuate. Also,
low-input crops don’t command higher prices like organic products
do, so they may be less profitable than conventional products, she
says.

Even as researchers fine-tune low-input strategies in
experimental plots, farmers are beginning to apply these tactics in
their own fields. It’s unclear how many farmers are taking on a
fusion farming approach, but a survey of 2,012 farmers across the
US found they are increasingly using green techniques, such as
planting cover crops, and that acreage planted in cover crops
nearly doubled between 2012 and 2016.

Photograph shows tall organic corn stalks growing in a field.

Organic crops such as corn (pictured) typically produce lower
yields than their conventionally grown counterparts. That casts
doubt on the ability of organic farming to feed the world’s growing
population. But fusion farming techniques, which combine organic
and conventional approaches, have higher yields, providing a path
to feed more people while reducing environmental impacts.

CREDIT: PHOTO BY BOB NICHOLS / USDA-ARS

And in an analysis of 400 global sustainable farming programs
published last year,
Pretty and colleagues  found that 47 of
the initiatives are running on a large scale, meaning they are
practiced on more than 10,000 farms or the same number of hectares
(almost 24,700 acres) of farmland globally. Some 163 million farms
— 29 percent of global farmland — are now solidly on sustainable
ground, Pretty says, meaning that outcomes such as yields are at
least maintained while doing at least no further harm to the
environment. Many of the programs achieved this feat not by pure
organic practices but through a plethora of low-input fusion
farming practices such as agroforestry, where trees are planted in
crop fields to help fertilize soil without the need for synthetic
nitrogen, or by integrated pest management, where natural predators
are used instead of synthetic pesticides to control pests.

Sustainable systems are “popping up at scale all over the
place,” Pretty says — momentum is building as farmers see
sustainable practices working. “We are at a turning point. We can
produce more with less impact. We are moving towards greater
sustainability,” he says.

Eco-friendly future

None of this means that eco-minded eaters should stop buying
organic produce, Seufert says. On local scales, organic farming is
an important part of the movement toward producing more food with
fewer impacts. But the global larder won’t ever be stocked with
just organic produce — doubling or even tripling organic farmland
is a more realistic and environmentally desirable target, she
suggests. The challenge is to ensure that the remaining global
farmland gets onto a more sustainable footing, and she and others
see low-input fusion farming as a promising path.

But this future won’t hinge just on farmers adopting greener
techniques, analyses conclude. Researchers who study food security
and sustainable agriculture say that our diets must change, too
(cutting back on red meat is key). A broader move to greener
pastures would also require new government policies that ban toxic
pesticides and remove unhelpful subsidies.

For now, research is making strides by enabling a deeper
understanding of what eco-friendly farming actually is. Says
Balmford, “We can’t afford to be ideological about what sustainable
systems look like.”

This story was originally published by Knowable Magazine. Knowable Magazine is an independent journalistic endeavor from Annual Reviews.

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