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 U.S. 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.

Red clover (foreground) grows alongside corn (background) in a crop rotation experiment at Iowa State University's experimental farm in Boone County. | (PAULA R. WESTERMAN/Courtesy Knowable Magazine)

"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.

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 U.K., 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 U.K. "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."

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. (FiBL 2011/Courtesy Knowable Magazine)

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 U.S., 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.

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). | (Adapted from V. Seufert/Science Advances 2017/Courtesy Knowable Magazine)

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. 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.

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 U.S. Department of Agriculture's Agricultural Research Service Farming System project, in Beltsville, Maryland. | (MICHEL CAVIGELLI/USDA-ARS/Courtesy Knowable Magazine)

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.

Read the rest of the story at Knowable Magazine. Knowable Magazine is an independent journalistic endeavor from Annual Reviews.