A middle path to sustainable farming

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.

“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.”

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.

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.

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.

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.

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.

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.

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.”