2017/04/01 by Beth H. Baker · 1 citation
Agricultural and Biological Sciences · #Agriculture #Agriculture, Land Use, Rural Development #Agroforestry #Archaeology #Business #Environmental science #Geography #Sustainable agriculture
paper · pdf · doi:10.1093/biosci/bix018
openalex publication_date 2017/04/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/30
A Kernza perennial grain field, grown by farmer Charlie Melander near Salina, Kansas. Photograph: The Land Institute. In October, a flurry of news articles hailed the arrival of a new beer produced by Patagonia Provisions, an offshoot of the outdoor clothing company. Long Root Ale is the first beer to be made from Kernza, a perennial grain bred from intermediate wheatgrass (Thinopyrum intermedium) by the Kansas-based Land Institute. Dubbed “an ecologist's dream” by a Washington Post food writer, Kernza is on the leading edge of a global effort to develop perennial crops as a way to make agriculture sustainable and to support ecological intensification. Plant geneticists, evolutionary biologists, agronomists, food scientists, and agroecologists are collaborating to develop perennial crops, among them rice, wheat, sorghum, pigeon pea, barley, and sunflowers. A 2013 United Nations Food and Agriculture Organization expert workshop on “Perennial Crops for Food Security” concluded, “As feeding 9 billion people in 2050 with increasingly scarce and degraded natural resources is the main challenge faced by humankind, reinvigorating agriculture in a sustainable and productive way on a large scale will take nothing short of a significant shift in agriculture as we know it.” That effort has been the Land Institute's mission since it was founded in 1976. Its goal is to transform farming from annual monoculture to perennial polyculture. “We’re trying to develop an agriculture that functions more like the ecosystem that agriculture replaced,” says Tim Crews, director of research and lead scientist of the Land Institute's ecology program. “In order to develop that ecosystem, you need perennial crops. They are not the goal, per se, but a central component of a more functional ecosystem. That will include transformation of the soil microbiome, and it will involve numerous crop species on the landscape.” For millennia, humans have bred plants to grow faster and have higher nutrient value. Agricultural production accelerated dramatically during the “Green Revolution” of the 1970s, with farmers urged to use chemical fertilizers and pesticides and to intensify the mechanization of planting and harvesting. Productivity rose at astonishing rates. Today, in the Midwest, rows of soybeans and corn dominate much of the landscape that was once prairie. Lee DeHaan, lead scientist with the Land Institute's Intermediate Wheatgrass Program, with interns and graduate students, collecting data and hand threshing Kernza perennial grain. Photograph: The Land Institute. In Malawi, Sieglinde Snapp, of Michigan State University, uses a participatory research approach to work with local farmers who plant perennial pigeon pea along with maize, the staple crop. “These mixtures fit well in the marginal areas,” says Snapp. “It's providing options to improve overall productivity along with these other ecological benefits. We’re looking at yield sustainability and quantifying environmental benefits under different conditions.” The project, which is supported by the government of Malawi and USAID Africa RISING (Research in Sustainable Intensification for the Next Generation), allows scientists to use weather-station data linked up to crop modeling to develop extension recommendations for farmers. “The farmers are using perennial pigeon pea in polycultures, an approach we have systemized and are now testing at scale to see the impact on environmental properties across the landscape,” says Snapp. Polyculture, as it turns out, has been practiced all along by many small farmers in Malawi. “It took a while to find them,” says Snapp. “We evaluate what farmers are actually doing. We’re discovering you can combine modern varieties of pigeon pea with these historic practices, and the combination makes it a lot more sustainable.” “Modernizing was all about yields,” says Sieglinde Snapp, professor of soils and cropping systems ecology at Michigan State University, who leads a project to bring perennial grains to Africa (see the box at right). “If you just compare crops on yield, then you can’t beat fertilized corn. But if you also want green cover for the Earth and nitrogen fixation and clean water, you have to measure them and give the plant credit for that.” Agriculture, she argues, should be directed toward both ecological services and food production. Kernza and other long-lived crops have much longer root systems than annuals do, allowing the plants to survive for several years without disturbing the soil. By planting perennial grains along with cover crops, such as alfalfa, farmers can reduce the need for tillage and for fertilizers and pesticides while fixing nutrients into the plants. As Lee DeHaan, lead scientist of the Land Institute's Intermediate Wheatgrass Program, and colleagues noted in the August 2006 BioScience, “The superior capacity of perennial plants to store carbon, manage resources, and stop soil erosion is widely recognized among ecologists and soil scientists, yet in 2006, only a handful of plant breeders are working to develop perennial grain crops.” The pace is now picking up, thanks to advances in genome sequencing and in understanding the role of the soil microbiome. Support has come from the Gates Foundation, the US Agency for International Development (USAID), dozens of research institutes, and others. Also spurring the research in the Midwest is growing concern over change in climate and over water quality degradation, says Craig Sheaffer, professor of agronomy and plant genetics at the University of Minnesota who collaborates with the Land Institute. “In the last 10 years, the issue of carbon sequestration has become more important,” he says. “Likewise, in Minnesota, there has been much greater emphasis on water-quality issues.” State agencies have documented sediment loading of rivers from field runoff, and there are a growing number of wells and streams whose waters exceed federal drinking-water standards for nitrate. How climate change might affect perennial polyculture, on one hand, and how perennial polyculture might help mitigate the adverse effects of a warmer, drier climate, on the other hand, are big questions. “We’re interested in how much carbon can be sequestered in a perennial grain system,” says Crews. “There are all sorts of approaches people talk about to mitigate atmospheric carbon dioxide with land-use changes…. Most tilled lands have lost between 30 and 60 percent of their soil organic matter. How do you get that back?” By replacing annual crops with perennials, he says, carbon, over time, can be re-sequestered. “Over decades, it should be possible to approach where the ecosystem was to begin with, as long as the soil had not been too degraded from annual cropping,” says Crews. John Mai, former technician for The Land Institute's perennial wheat breeding program, working with wheat hybrids. Genome sequencing has accelerated progress in perennial plant breeding. Photograph: The Land Institute. As the climate becomes hotter and drier, researchers are breeding plants that can survive in tough conditions. The Land Institute, for example, is domesticating silphium as a substitute for annual oilseed crops. A native prairie perennial, silphium survived the Dust Bowl and other extreme events by extending its taproot, several meters long, deep into the ground for water. “Ultimately, we’re looking to be able to grow these [perennial] crops profitably on lands in order to result in improved ecosystem services—improve soil quality, reduce runoff and nitrogen leaching, and improved water quality and wildlife habitat,” says DeHaan. For now, “the breeding program is focused primarily on grain yield, because it is essential to the economic success of perennial grain systems.” The Land Institute use two strategies to breed plants: domesticating wild species, as it did with Kernza, and crossbreeding perennials with annuals. Advances in genome sequencing have been “a game changer in what we can do in terms of genetics of any of our crop plants,” says DeHaan. The wheat genome, for example, is nearly complete. “We don’t know what all the genes are and what they do—but the complete sequence is there, and that serves as a reference. Now, we can pull in the information from other model species and organisms. We’ve studied many genes for decades, and now we can look for those same genes in our crops.” DeHaan's team is identifying genes that confer superior yield, shatter resistance, seed size, and grain quality. “We can plant thousands of seedlings in a greenhouse, take their DNA, sequence these small portions, and predict which will be the best without growing them to maturity, based on these genetic markers,” says DeHaan. “By the next spring, we can select again—we can do much more rapid cycling.” The research that led to Kernza began in 1983, with plant breeders at the Rodale Institute experimenting with intermediate wheatgrass. Twenty years later, the Land Institute took up the baton. In the last decade, DeHaan's team has doubled Kernza's seed size and yield. DeHaan is optimistic that within two decades, Kernza will be nearly as economically viable and high yielding as traditional annual wheat. To speed up the development of perennial polyculture, the Land Institute collaborates with partners around the globe. At the Swedish University of Agricultural Sciences, biologist and plant geneticist Anna Westerbergh has been working since 2011 on developing perennial barley, an important cereal in Scandinavia. “We are using two different breeding strategies to develop cultivars for northern conditions,” she says. One is wide hybridization, crossing annual barley with its closest wild perennial relative, Hordeum bulbosum. The other is domesticating a perennial wild barley. “In addition, we have developed mapping populations as a first step to investigate the genetic basis of traits associated with perennial growth habit,” Westerbergh explains. “We have crossed annual and perennial species. We look at the diversity in traits and genotypes in offspring populations and try to associate the phenotypes with the variation in the genotype.” Comparison between annual wheat (Triticum aestivum; top) and perennial Kernza (Thinopyrum intermedium; bottom). The photograph was taken at spring growth, when the annual wheat is ready for harvest and Kernza is still flowering. Photograph: The Land Institute. Anna Westerbergh, of the Swedish University of Agricultural Sciences, studying a plant hybrid between wheat and a wild perennial relative. Photograph: Jenny Svennås-Gillner. Westerbergh is also involved with a multisite comparative study of Kernza and more than 20 wheat cultivars, along with the Land Institute and other researchers in the United States, Canada, China, Australia, Turkey, and Italy. “We are studying the interaction between the genotype and the environment to see how they behave in these different climates,” says Westerbergh. “We will be able to select which do the best, for example, here in Sweden for further breeding.” In China, geneticist Fengyi Hu of Yunnan University and colleagues have successfully improved through breeding a cross between Oryza sativa, an annual rice, with a wild African perennial, O. longistaminata. The cross, known as PR 23, is now being grown in test paddies, where, after 3 years, it is proving to be nearly as productive as annual rice. Papers are forthcoming, according to Crews, who collaborates with Fengyi Hu. Andrew Paterson, director of the Plant Genome Mapping Laboratory at the University of Georgia, is crossing wild and agricultural sorghums, seeking to transfer the perenniality trait while retaining high yield. In 2013, a team led by Paterson was awarded a nearly 5 million grant from USAID to develop a more drought- and heat-resistant sorghum for farmers in Africa and India. A secondary goal is to develop a semiperennial crop, with farmers getting a second crop out of a single planting. “Our notion is to try to combine the high level of productivity that's been accomplished through hundreds of years of breeding with the ability to survive a cold or dry season,” says Paterson, who led the genome sequencing of sorghum in 2009. “We have experimental materials that can do this in Kansas, where it's cold, and in Mali, where it's hot and dry. They don’t yet recover the high yield of elite sorghums, and they don’t necessarily have the quality factors that would be desired in Africa, where sorghum seed is substantially consumed by people. We have quite a lot of work to do, but we have proof of concept that this can be done.” Other researchers are focusing on the soil microbiome and its relationship to annual and perennial plantings. “We’re just beginning to appreciate the importance of microbes in plant fitness and in the structure of plant communities in land-managed systems,” says Jim Bever, distinguished professor of ecology and evolutionary biology at the University of Kansas. “There has been an appreciation for plant pathogens but less of plant mutualists. As we move to perennial agriculture, there are opportunities for exploiting mutualists and minimizing the effects of pathogens.” A single teaspoon of soil may contain a billion individual microbial cells from up to a million different taxa (left). Photograph: Ben Sikes, University of Kansas. To the right is a collection of spores from 9 different species of arbuscular mycorrhizal fungi from tallgrass prairie. How soil microbes affect perennial crop growth is a growing field of inquiry. Jim Bever. Bever's lab has found that longer-lived plants are more dependent on arbuscular mycorrhizal (AM) fungi that help the plants take up phosphorus and nitrogen. Perennial plants also are more particular than annuals as to which fungi species are in the soil. In conventional annual monocultures, tillage and fertilization damage these beneficial fungi. “What we’ve found in prairie restoration in fields that were tilled for many years is that when we reintroduce the native fungi, these perennial plants do much better,” says Bever. In a study published in the Journal of Applied Ecology in 2016, Liz Koziol, now a postdoc at the University of Kansas, and Bever found that test plots “inoculated with certain AM fungal treatments were dominated by desirable prairie plants, whereas plots inoculated with other AM fungal species and the noninoculated control were dominated by nondesirable plants, including weeds and exotic species.” Future research by Bever's lab will investigate whether Kernza and other perennial plants will respond favorably to these fungi. “We’re excited about the possibility of developing management applications to what we’ve been finding in unmanaged [prairie] systems,” he says. One unexplored area, says Bever, is the soil microbiome's role in improving the nutritional quality of perennial grains. “The arbuscular mycorrhizal fungi improve plant uptake of a lot of soil resources, such as phosphorus and nitrogen, and of course that gets packed into the grain,” says Bever, “so it will affect the nutritional quality. We haven’t looked at that in particular, and it's an interesting direction to go.” Bever's colleague at the University of Kansas, Ben Sikes, a soil microbial ecologist, studies the soil microbiome and its relationship to perennial polyculture. Among the big questions his lab is investigating, says Sikes, are the following: “What happens to the soil microbial community when you have no tillage? What happens when you have a plant that's there for more than one year, when the root system has more things accumulating over time than an annual plant? How does the polyculture or mitigate benefits that you might you have a higher diversity of plants, you have higher diversity of beneficial greater in growth and production. We don’t have any of the importance of those To his team the microbiome in of fields the Land Institute had one in annual wheat that is in perennial wheat and a that is prairie. 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