Photograph by James L. Amos, Nat Geo Image Collection
Read Caption
A wasp and a copper butterfly pollinate thistle on the Dumbbell Ranch in Wyoming.
Photograph by James L. Amos, Nat Geo Image Collection
The Plate

To Grow More Crops, Cultivate the Birds and Bees

There’s a point of view about raising crops that you hear a lot: if we’re going to feed the nine billion people who are expected to be inhabiting this planet in the year 2050, we will need to expand and intensify the farming we do now. That means producing at least twice as much food, at a time when the yields of major food crops are falling.

And doubling down on production is a problem, because there is not much land left. Most of what could be cultivated to grow food is already being worked; more than a third of the world’s ice-free surface is devoted to crops. Finding new spaces to farm could mean carving workable land out of forests and prairies, habitats that are essential for animal, bird and insect species to survive. Yet doing that sacrifices biodiversity—which could harm farming yields in turn as populations of pollinators and pest-eaters shrink.

How to solve this conundrum? A team in England, writing recently in the journal Proceedings of the Royal Society B, contends that we are looking at the problem backwards. They say that making room for habitat on farms not only protects biodiversity, it also improves crop yields—and does it without sacrificing growing space, because the habitats are built on small, low-yield parts of the farm.

View Images
A strip of farmland planted with wildflowers. Photograph by Richard Pywell

“This study provides more evidence that nature provides multiple benefits to people, including aiding food production. This is great news for both farmers and nature conservation, and is counter to common practices of removing natural habitat to boost yields or reduce pests,” Paul C. West, co-director and lead scientist of the University of Minnesota Institute on the Environment’s Global Landscapes Initiative, who is not connected to the research, tells The Plate.

“Several studies have now shown cases where natural habitat helps either increase or maintain yields,” West says. “In some places, yields are improved because there is good nearby habitat for pollinators; in other cases, yields are maintained or even improved by an abundance of species that provide natural pest control. Natural habitat on farmlands provides many other benefits too, like soil conservation, improved water quality, and carbon storage.”

To prove their assertion that less but better-managed land improves yield, the team conducted an experiment on a conventional commercial farm in southwest England that grows grains and fodder crops in rotation, primarily wheat, oilseed rape and field beans. On two-thirds of its fields, they took either 3 percent or 8 percent of the growing area out of production, choosing the already low-performing edges and corners where tractors do not fit well and fertilizers and pesticides cannot reach. (The remaining third was managed normally, to provide a comparison.) They sowed the unproductive areas with grasses and flowering plants that provide food for birds, bees and other insects. Then, over five years, they measured the fields’ productivity, and took censuses of the new habitats as well.

“The original idea was to ask whether we could have profitable farming but at the same time support farm wildlife,  birds, bees, butterflies that have declined due to intensive farming,” Richard F. Pywell, the lead author and a senior principal scientist at the UK government-supported NERC Centre for Hydrology and Ecology, tells The Plate. It turns out, if you do wildlife-friendly farming right, you will actually increase profits, he says.

View Images
A bee visits the flower of a field bean plant. Photograph by Lucy Hulmes, NERC Centre for Ecology & Hydrology

The “business as usual” approach, Pywell says, would have been to pour effort and chemicals into the unproductive field edges, which costs money and increases the effort the farmer puts in, but seldom has much result. Giving those areas back to wildlife, and supporting the wildlife with their preferred plants, cut out that effort and cost, while encouraging birds and insects that are natural enemies of farm pests such as aphids and weevils. For two of the crops, wheat and rape, the yield in the fields remained the same even though some of the square footage had been subtracted for habitat. For the third crop, beans, yield actually increased from the untreated fields, and was highest on the fields where the largest amount of habitat was created.

The effect was not immediate, he cautioned: It was at least four years before populations in the habitats picked up enough to have an impact on pests. But once they did, “the farm family really began to engage with the project,” Pywell said. “They liked seeing all these birds that they had not seen in so long. Whereas they were quite skeptical at first: ‘Flowers, what’s the point of that?'”

The beauty of this result, Pywell said, is that it can be replicated wherever farming is done; each area will have its own pollinators to be encouraged and pests to be combatted. In fact, a similar technique—planting belts of flowers to provide food and shelter for bees—has already improved yields in blueberry fields in Michigan and mango orchards in South Africa, and some European countries now encourage farmers to plant wildflower strips alongside any intensively cropped area.

Using small parcels such as field edges and corners to create habitat could help solve an ongoing dispute between agriculture and conservation: whether land must be set aside to protect biodiversity.  The international agriculture research consortium CGIAR argues that such “land-sparing” schemes increase competition for land, because the best land for farming may also be the land that wildlife would prefer. “Land-sharing,” though, allows the two uses, for food and for biodiversity, to occupy almost the same space—and, as the British experiment shows, to the benefit of both sides.

And since a key focus of World Food Day this year is ending hunger through promoting agriculture, the land-sharing solution may help us nudge us closer to that goal of increasing crop yields.

But at the University of Minnesota, West cautions that there may be some limitations. “The findings likely don’t hold up everywhere since there are so many types of farming practices, crops, and natural habitat. Ideally, studies like these can be translated into a sets of regional guidelines that farmers can use to boost production and provide other benefits.”

He adds, “It’s critical that we keep in mind that not all species thrive in small patches within farmlands. Practices like these can complement, but not replace, larger reserves or managed areas that meet the needs of species that require large areas or specific habitats.”