Since the dawn of agriculture, farmers have hit the reset button every year. That’s because most are dependent on annual crops, frequently working the soil to suppress weeds and nurture the season’s harvest. Ecologically, this cycle of production can be shocking, leading to soil erosion, nutrient runoff and carbon loss. That’s why some farmers are now championing a perennial revolution.
These crops could also be a potential tool for fighting climate change and provide more resilience to weather extremes. “Foodstuffs that don’t need to be planted every year are a total no-brainer. How can we not look at this and think perennials aren’t the future?” says Mandy Barber, co-founder of Devon-based perennial vegetable breeder, Incredible Vegetables.
Crops that come up year after year aren’t new, there are thousands from apples to strawberries, coconuts to grapes, olives to spinach. Yet 85 per cent of the global population’s food calories and the vast majority of planted farmland worldwide are based on annuals, where monocultures of wheat, rice and corn that require replanting every year dominate.
“These crops require a lot of land management, driving ten times per season with tractors over the land is not uncommon; with perennial crops this is reduced to three or less,” states Professor Lennart Olsson, from the Lund University Centre for Sustainability Studies in Sweden.
Perennial crops are now being developed across the globe. In the US, over 1,000 acres are planted with a crop called intermediate wheatgrass, producing a grain called Kernza, which is already being turned into breakfast cereals, even beer. In China, perennial rice was given to farmers in southern Yunnan province in late 2018.
“Even if we have two crops that are beginning to enter the commercial world, they still represent proof-of-concept,” says Professor Tim Crews, director of research at the Land Institute in Kansas, where researchers are developing Kernza and other perennials, such as oilseeds and legumes.
“The greatest practical barrier standing between the world's croplands being planted to perennial rather than annuals is the successful breeding of perennial varieties that will produce sufficient food of adequate quality to displace current annual species,” he adds.
Mankind has been breeding wheat and other grains for 10,000 years. In contrast, perennial Kernza is only decades old, and the grains that are harvested and eaten are a fifth of the size of most conventional wheat varieties. This means you need a much higher acreage to get the same yields as traditional wheat. It will take time to breed a variety with a bigger grain, says Crews, who adds: "some may be ready to trial in five to ten years, but most will take longer."
Already the benefits are obvious. Kernza roots extend three metres or more beneath the soil surface. This is greater than twice the depth of annual wheat roots; they are also in greater density.
“Currently, annual grain crops lose 50 per-cent of the nitrogen applied and this can even be the case in organic systems. Perennial grains leak almost no nitrogen. The savings on inputs including seed, fuel and labour will be hard to match compared to outdated annual agriculture,” Crews continues.
Because of their long roots, established over a number of seasons, perennial crops can also reduce erosion by as much as 50 per cent and improve soil structure. They also increase nutrient retention, carbon sequestration and are a lot better at conserving water. All great qualities for so-called climate-smart agriculture in the 21st Century.
“After the Beast from the East and the summer heat of 2018, our perennial vegetables survived and thrived in the worst of it,” explains Barber, of Incredible Vegetables. It’s not just wheat or rice that’s now a focus, research is ongoing to create perennial strains of oilseeds – silphium is promising – as well as sunflowers, sorghum, legumes and others.
“Even if you take a list of 20 common annual vegetables there are perennial alternatives for all of them. They are less well known, but they not only come into their own in the hungry gap, they are also some of the earliest to start growing and cropping at the start of the season,” explains Barber, who’s been busy working with perennial broccoli, kale and alliums.
So, what's holding perennials back? Understandably, there’s no money in it for seed producers, agricultural corporations and big business, who rely on selling new seeds every year. Try and get hold of perennial seed and plants and you will find them in short supply. What’s needed is a shot in the arm from governments, academic institutions and philanthropic sources.
“We think public funds will be key to transforming the agricultural sector to perennial systems. But we need sustained funding over decades, applied to multiple crop species,” explains Crews.
The end game is not to replace monocultures of annuals with perennials, but to create meaningful plant communities that achieve high levels of ecological intensification. For instance, the Land Institute is intercropping Kernza with the nitrogen-fixing alfalfa. The aim is to create agro-ecosystems that sustain their own fertility, suppress pests including weeds, insects and diseases and use minimal amounts of fossil fuels.
“In the future we will look back on this time and how the ‘perennial revolution’ averted a looming climate and food crisis and how perennial polycultures prevented an ecological collapse of many ocean areas where dead zones have spread since the 1970s,” says Olsson.
“In 2070, schoolchildren will read about the perennial revolution, like the nitrogen or the green revolution, as a period in the 2020s and early 30s when agricultural practices changed profoundly all over the world,” he predicts. Now, there’s a thought.