Is Polyculture The Key To Food Security?

Growing a single crop over vast amounts of land has become the norm. But in the face of a destabilising climate, plummeting biodiversity, and a rapidly growing human population – could growing multiple crops be a better way to approach farming?

Polyculture means growing more than one crop or livestock animal simultaneously, unlike monoculture, where farmers cultivate a single species. When well designed, polycultures minimise competition between species and the amount of management and harvest labour required.

For example, it would take nearly twice as much land to grow corn, beans, and squash in a monoculture instead of growing them together.¹ This is a sustainable farming technique known as “The Three Sisters”, which has been practised by Indigenous Peoples for centuries.² And it’s not a standalone example of how farming could be more diverse. For much of human history, polyculture was the norm.

The rise of monocultures

In the past, most farmers grew various crops and livestock to feed their families, with surplus food sold at local markets to earn a disposable income. Today, most of our food is grown in monocultures, and in many countries the size of the average farm has been steadily increasing.³ Farmers tend to produce fewer crops in larger amounts, which they often sell at distant markets. They then use the money earned through this work to meet their daily needs.⁴

The reasons for this shift to larger farms and monocultures are dizzyingly complex. But many of them are linked to market forces, specifically the emergence of market capitalism, an economic system that has been dominant since the breakup of feudalism.

If you’re anything like me, these terms can feel complex and intimidating. But here’s what you need to know, in simple terms.

Crops have become a product to buy and sell at global markets rather than simply food to nourish hungry bellies. We now have a global food market worth US$9.36tn, largely thanks to “cash crops” - a crop grown to sell rather than to feed the person who grew it.⁵ The cash crop might be bought directly by a consumer, fed to livestock, or processed into another product.

Theoretically, there are positive aspects of treating food like any other product. For example, if we’re not all farmers, some of us can specialise in other industries. We can become doctors, or teachers, or artists, to the benefit of all of society. Global markets also mean that if there is an extreme weather event in my sleepy mountain village, my family and neighbours aren’t going to starve - we’re going to buy food imported from somewhere else. Of course, that comes with the caveat that I live in one of the richest countries in the world, which gives me an opportunity to access more expensive, imported food. Not everyone is so lucky.

However, there are also problematic aspects to treating crops as a product. For example, feeding livestock with grain from the other side of the world. As supply chains get stretched, they can easily become less transparent. If imported grain is not traceable, it’s impossible to know whether that grain was produced ethically, sustainably, or even legally.^6,7 What’s more, when we grow a large amount of our food for global markets, countries that may need this grain for their own population can end up exporting their own staple crops to countries where people have more than enough food.^8,9 While there are economic benefits to international trade, that doesn’t mean much for the people going hungry.

Farmers harvesting Edamame, or fresh green soybeans, in Wenling, Taizhou City, China. (Photo Liu Zhenqing/VCG via Getty Images)

Natural limits

Professor Frank Uekӧtter has been working with the University of Birmingham and Ruhr-University Bochum on a 5-year research project looking into the history of monocultures, funded by the European Research Council.

According to Frank, growing for distant markets can indeed raise some concerns:

“Subsistence farming has a natural saturation point. Once your belly is full, you don't need to keep pushing for more harvest. But in market capitalism, there is no saturation point. When supplying to a faceless market, there is a constant push to produce more."

This drive to produce more can mean that natural limits are not respected, ultimately causing problems like soil erosion, water pollution, or disease outbreaks.

There are, however, some potential benefits to monoculture systems. For example, some argue that farmers can grow large amounts of a crop that will do best in their soil and climate, helping produce food more efficiently. Monoculture systems are easier to mechanise on a large scale because farmers can invest in large machinery specifically designed for a particular crop.¹⁰

Whereas some people see this increased efficiency as good for farmers and food security, others argue that it pushes farmers into increasing financial vulnerability as they must keep investing in new machinery to keep up with improved technology in other farming operations. Heavy machinery and increased use of synthetic inputs can also have social and environmental consequences.

Monocultures in crisis

Despite producing most of our food, Frank explains that monocultures operate in perpetual crisis mode.

“Monoculture comes down to magical thinking. It's a type of production that doesn't have a strong theoretical base, but we have been able to get away with it for a time under certain circumstances. But in the research we’ve carried out, we can see that monoculture isn't necessarily more efficient and certainly doesn't make people happier."

One of the crises that monoculture faces is a growing pest and disease burden, which can financially devastate growers and put food security at risk.

"In monoculture,” Frank tells me, “you concentrate many species into the same place. And that concentration breeds pest and disease problems. It’s just like with Covid: if you put many people on a bus, the disease will spread. Monoculture puts plants at risk of pest and disease, and farmers must invest in more technology and inputs to deal with them”.

In 2022, Spain's Andalusia region - the world's largest olive-oil producing region - saw yields slump by half the usual quantities as a result of extreme heatwaves and ensuing drought. (Photo Carlos Gil/Getty Images)

Benefits of polyculture

Diversifying crops and livestock is one possible solution to the problems that monoculture systems pose. Here are some of the benefits of polyculture systems:

Yield

Even though the yield of a single crop can be lower in polyculture, the combined yield from the system can be higher than that of individually growing the same crops.

For example, farmers growing timber trees amongst crops in France found they could produce the same yield in 100 hectares as they would be able to grow in 130 to 140 hectares of monoculture trees and crops.¹

Biodiversity and pest management

The increased yield in some polyculture systems can positively affect biodiversity because farming production can be increased on existing farms – rather than converting more natural spaces for agriculture.¹

On-farm biodiversity can also be higher in polyculture systems, thanks to a wide range of plants which attract different wildlife species. These wildlife species include predatory insects, which naturally help keep pest species in check and pollinating insects, which we at least partially rely on for 75% of crop species.^11,12

Soil health and fertility

Polycultures often use crops which complement one another. For example, certain legumes like peas and beans can boost nitrogen in the soil thanks to nitrogen-fixing bacteria. Farmers can reduce their reliance on synthetic fertilisers by working with nature's synergies, saving money and reducing the associated pollution.

Read about how synthetic fertilisers are feeding the world - and at what cost

Animal wellbeing

In polyculture systems, certain farm areas can be made into temporary grasslands so that the land can rest and recover from cropping. Small herds of animals can benefit from grazing on these temporary pastures, producing meat and dairy for the farmer and often experiencing a higher quality of life when compared to animals raised in restricted indoor spaces.

Resiliency

Growing multiple species of crops can help farmers keep producing food in the face of a rapidly changing climate. If unexpected weather wipes out one crop, having several others to sell that year can be a lifeline. Additionally, polycultures have been shown to outyield monocultures in droughts.¹ In the face of a changing climate and the increased frequency of extreme weather events, this is not to be overlooked.

Polyculture in practice

So, what does polyculture look like in practice? Here are a couple of examples of how diversity in farming can work at its best.

La Dehesa

La Dehesa is a Spanish agroforestry system which produces a wide range of materials on marginal land.

La Dehesa includes grassland for cattle, goats, or sheep, as well as cork oak trees to produce cork, a valuable and sustainable material. Acorns from oaks can also feed grazing pigs when their acorns fall in autumn. Other tree species provide shade to animals, as well as firewood or timber. Some farmers also choose to grow cash crops at certain times of the year.

This diverse approach to agriculture maintains a precious habitat for Black Shouldered Kites, Eagle Owls, the Iberian Lynx, and various endangered beetle species.^13,14,15 As farm animals graze between trees, they reduce the fire risk, particularly in a brittle environment, where plants like brambles and dry grasses can act as fuel for wildfires.¹⁶

Tropical Home Gardens

Another example of polyculture can be found in Southeast Asia, where people have grown tropical home gardens for up to 13 000 years.¹⁷ Food plants, cash crops, medicinal plants, energy crops, and building materials are grown near the home in a multi-layered system that looks and functions like a wild forest. There are many layers of plants, some covering the ground, some shrubs, some trees, and vines which climb and knit the forest together.¹⁷

Tropical home gardens sequester carbon much like the wild forest, provide habitat to wildlife, and provide sustenance and income for families. They are high-yielding systems, meaning they produce large amounts of crops useful to people, and are a crucial example of how wildlife and human needs can coexist.

Drawbacks of Polyculture

Polycultures can be more complicated to manage than monocultures, particularly when crops mature at different times. Diverse systems are also difficult to mechanise, making them more labour-intensive. It can also be more challenging for farmers to access subsidies and grants when they choose to produce food differently from the status quo.

But there are often solutions to these problems. For example, sheep can graze the “weeds” between vineyards to reduce time spent weeding – and farmers can then sell the associated meat, wool, or milk. As the biodiversity and climate crises continue to unfold, polyculture is a practical tool that we can use to keep producing food in more difficult circumstances.