Are perennial intercrops of arid-adapted plants the answer to the agriculture of the future?

A man in a blue shirt, blue jeans, and hat prepares a fire pit to roast fresh agave at Mission Gardens.
Fire roasting agave at Mission Gardens.

As heat waves, drought, and disease challenge food security in the Southwest U.S. and Mexico, scientists set their sights on a novel model for desert farming.

Just as the U.S. National Weather Service warns that a heat wave spreading across the southwestern United States is of a “magnitude rare, dangerous, and deadly” to food producers and consumers, a team of scientists has generated a new vision aimed at reducing climate disruptions to food security, human health and rural economies.

Fourteen scientists from the U.S. Southwest and Mexico present a climate-smart model for farming in arid landscapes designed to simultaneously benefit land health, reduce disease risks, and restore economic well-being to desert communities. The researchers propose restructuring desert food production from the ground up by selecting wild food crops already adapted to extreme conditions. The desert food plants will be intercropped in designs that not only reduce heat stress in the plants, but among the farmworkers who care for them as well. 

The new article, titled “An Aridamerican model for agriculture in a hotter, water scarce world,” was just released in the journal Plants, People, Planet. It calls for a dramatic paradigm shift to move desert food production in the opposite direction of the high-input annual cropping systems that now appear to be failing worldwide. Conventional agriculture attempts to reshape land and water resources to buffer crop monocultures from adversity, a strategy that is is becoming increasingly costly and unsustainable under rapidly changing climate and soil conditions. Instead, this vision selects crops from wild, resilient native species already adapted to aridity.  

“Desert plants have evolved a remarkable number of strategies to cope with heat, drought, unpredictable rainfall, and poor soils” said Erin Riordan, the principal scientist coordinating the binational research team anchored at the University of Arizona’s Desert Laboratory on Tumamoc Hill. She points out that such stressful agronomic conditions are predicted to dominate over half of the world’s land surface in the coming century.

The interdisciplinary team of prominent ecologists, anthropologists, ethnobotanists, restoration ecologists, and public health professionals marries elements of high-tech energy and water harvesting solutions with the traditional ecological knowledge of desert foragers from the dry regions of North America called “Aridamerica.”

A map showing the dry regions of North America called "Aridamerica" in yellow including the Sonoran Desert area, and the beginnings of Mesoamerica shown in blue.
A map of the dry regions of North America called “Aridamerica” including the Sonoran Desert.
A man in a t-shirt, blue jeans, and a hat plants rows of agave at the Mission Garden.
Agave planting at Mission Garden.

“We see today’s deserts not as wastelands but as laboratories for the future of agriculture,” said Gary Paul Nabhan, the lead co- author, a MacArthur award-winning agroecologist who convened the new study. Nabhan is the Endowed Chair in Food and Water Security at the University of Arizona.

By combining ancient and cutting-edge strategies for dealing with rising temperatures, water scarcity, and diseases exacerbated by heat stress, the scholars hope to make food production less daunting, dangerous, and deadly for future desert dwellers. The new model co-locates renewable energy production, rainwater harvesting, and no-till food cropping of hardy perennials in the same spaces. The placement of desert food plant polycultures in the “understory” of shade trees and photovoltaic panels simultaneously allows for partial shading, soil moisture retention, soil microbe proliferation, and carbon sequestration.

By relying on heat- and drought-adapted food species such as agaves, cacti, and nitrogen-fixing legume trees, these agroforestry systems can provide reliable, nutrient-dense yields with minimal inputs in the face of climate uncertainty.

“Cacti and agaves have functioned in many traditional cultures in Aridamerica as a form of insurance against environmental vagaries and annual crop failures,” says Exequiel Ezcurra, a University of California ecology professor globally renowned for both his desert research and conservation of biodiversity.

A man in a t-shirt, blue jeans, and a hat plants rows of agave plants of various sizes at Mission Gardens.
Planting rows of agave at Mission Gardens.

Desert food plants not only benefit land health, but human health as well. Unlike corn, sorghum and sugar cane that produce simple sugars that aggravate obesity and adult-onset diabetes, perennial desert crops offer multiple means to prevent these diseases. The 17 genera of desert plants highlighted in the study reduce blood sugar levels and provide a diversity of anti-oxidants that are essential to buffering humans from the negative consequences of chronic illnesses that are being exacerbated by heat stress. Rather than investing most health care dollars in costly end-of-life hospitalizations, the authors propose shifts in public investments to producing chemo-preventive foods and medicines to deal with health risks upfront.

To be sure, these water-efficient succulents and nitrogen-fixing tree legumes may take five to 12 years to produce their first nutritional harvests. Nevertheless, they can produce more edible biomass over a decade with far less water than that used by conventional annual crops, while sequestering carbon into the soil to mitigate climate change.

“We call such steadily-producing arid cropping systems slow agriculture, because they are like the desert tortoises who will ultimately win the race,” said Nabhan. “They require few inputs other than patient capital and innovative farmers to restore food production potential to marginal lands that have been salinized, compacted, or depleted of their microbial diversity.”

In Metro Tucson, where much of the research of this interdisciplinary team has emerged over four decades, more than 120 new desert food and beverage products have emerged from 40 start-up microenterprises. Most of these “slow foods and drinks” have appeared in the marketplace since Tucson was designated as the first UNESCO City of Gastronomy in the U.S. six years ago.

The timing of this work is critical. With accelerating climate change and new pandemics, the research team warns that food security in arid regions will dramatically deteriorate over the coming decades unless new strategies are put in place. Pilot projects to test this proposal are now underway in both the United States and Mexico. At the Via Organica Farm in Guanajuato, mesquite, agave and cacti are intercropped for food, drink and carbon sequestration. The agrivoltaic component of this study, where perennial crops are grown under solar panels, is being tested at Biosphere 2 and three public schools in southern Arizona, and is being installed in the Comcaac (Seri People) village of Desemboque in Sonora, Mexico.

This photo shows intercropping of agave and columnar cacti near Las Canoas in Jalisco, Mexico.
Intercropping of agave and columnar cacti near Las Canoas in Jalisco, Mexico.
Image credit: Bill Hatcher.

Read the full article here: https://nph.onlinelibrary.wiley.com/doi/10.1002/ppp3.10129

This guest blog was authored by Dr. Gary Paul Nabhan and Dr. Erin Riordan

Dr. Gary Paul Nabhan

W.K. Kellogg Endowed Chair in Food and Water Security

Southwest Center

University of Arizona

gpnabhan@arizona.edu

Dr. Erin Riordan

Postdoctoral Research Associate

Desert Laboratory on Tumamoc Hill

Laboratory of Tree Ring Research

University of Arizona

For further information contact Jesús García, jgarcia@desertmuseum.org.


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