Growing Food in a Hotter Drier Climate

An Interview with Gary Paul Nabhan

Gary Paul Nabhan, Ph.D., a world-renowned, Arizona-based Agricultural Ecologist, Ethnobotanist, Ecumenical Franciscan Brother and author whose work has focused primarily on the interaction of biodiversity and cultural diversity in the arid, bi-national Southwest, is considered a leading pioneer in the local food and heirloom seed-saving movements.

Among many other achievements, he co-founded Native Seeds/SEARCH (which hosted the first-ever national conference on community-based seed banks and heirloom seed-saving); served as Director of Conservation, Research and Collections at both the Desert Botanical Garden and Arizona-Sonora Desert Museum; was founding Director of the Center for Sustainable Environments at Northern Arizona University; and founded the Center for Regional Food Studies. His many prestigious awards include a: MacArthur Fellowship, Pew Scholarship in Conservation and Environment, John Burroughs Medal for Nature Writing, Southwest Book Award, Lannan Literary Award, Society for Conservation Biology Distinguished Service Award, etc.

Arty Mangan, Bioneers Restorative Food Systems Director, interviewed Gary Paul Nabhan in October 2019 at the Bioneers Conference.

ARTY: With climate change, drought is already a major issue particularly in the North American West. You’ve done a lot of work in the Southwest, a traditionally arid region; what are some of the strategies that have potential for broader use in agriculture as the climate gets hotter and drier?

GARY: There is a need to have greater reliance on rainwater harvesting. For 100 fruit trees of about 45 species, growing on my five-and-a-half-acre property, a primary source of water is rainwater that we gain through micro-catchments and diversion from hillsides into sunken beds. Secondly we get rooftop runoff. And thirdly we use micro-olla irrigation. Far more efficient than drip irrigation is a number of micro-aspiration techniques that slowly provide the same amount of water that a drip emitter would, but over four to five hours instead of 20 minutes. The yields under those conditions are about twice as high as conventional drip irrigation.

Secondly we’re really interested in our new experiments with agro-voltaics, something that started in Portugal and Southern France when they began to see a temperature spike there. We now have four pilot sites where we’re growing solar radiation and heat sensitive vegetables and herbs under photovoltaic arrays that are eight to 15 feet above the beds. They use the concept of biomimicry from Janine Benyus. Solar collectors act as nurse plants. Most desert plants begin their life under an ironwood tree or mesquite tree protected from harsh heat. The solar collectors not only shade young plants, but they can also be used to catch rainwater. That system co-locates renewable energy, renewable water use, and food production. 

There’s one more benefit. The highest spike in emergency room visits in Arizona and New Mexico and Southern California is from farm workers and other outdoor workers dealing with heat exhaustion, heat stroke, dehydration, and six other maladies that are increasing in severity and frequency because of high temperatures. If farm workers work 60 percent of the time in the shade of solar collectors, their work productivity goes up. Their risk to emergency room visits and long-term problems, like muscle wasting and other issues that are becoming more common with climate change, is buffered greatly. We get better worker health, a higher brix in our vegetables, fruits and herbs, and we’re not depleting the environment by using fossil fuel and fossil water. Instead, we’re using rainfall and solar energy to drive our agro-ecosystems.

ARTY: What kind of crops can you grow in that system?

GARY: We’re focusing primarily on summer, warm season crops – vegetables and fruits that require multiple harvests, because those are the ones that can really help the farm workers have better occupational health conditions. Mint, stevia, basil, a number of culinary herbs, and many of the vegetables that require multiple picking like green beans and squash do really well with just 60 percent of the ambient light that we would get if they were grown out in the open. Their yields go up and their brix content or nutritional density goes up at the same time that there is better farm worker comfort. 

ARTY: Are there other strategies for heat stress on crops?

GARY: In addition to using the photovoltaics to buffer crops from heat, I’m using the oldest concept in desert ecology that was discovered right where my office is at the 120-year-old Carnegie Desert Laboratory on Tumamoc Hill in Tucson, and that’s nurse plant ecology.  We’re using nature as a model – like Miguel Altieri and his work here in California on agroecology, and Wes Jackson is at the Land Institute – to look at the structure, function, and composition of desert plant guilds. Shade-providing trees help reduce the urban heat island effect with an understory of crops, wild or domesticated, grown underneath them. Much of my own orchard and gardens are set up that way. We have mesquite, elderberries, wild plums, and other trees as an overstory that helps shade the crops part of the day.

From my predictions, about 30 percent of all the crops that we’ll grow on 40 percent of the land surface of this planet over the next 50 years will be cacti and succulents, dragon fruit, prickly pear fruit. Purslane, a wild green, is also a cam pathway succulent with high water use efficiency. Agaves, sotol, yuccas have an eight-fold higher water use efficiency than conventional crops that use the C3 pathway Plants [about 95 % of all plants], like most of our vegetables, or sugar cane and corn that use a C4 pathway. [Comparing C3, C4 and Cam Plants]

Within the next 50 years we’re going to see, even as far north as Central to Northern California, a radical shift from herbaceous annuals and woody perennials to succulents. Luther Burbank’s garden in Santa Rosa, with his Burbank prickly pear, culturally appropriated from our Mexican friends, will be the norm rather than the exception as far north as Napa Valley and the great Napa Valley wine varietals will be grown from Eugene northward.

ARTY: Louise Jackson at UC Davis and has done research on crops in Yolo County to understand, with climate change, which crops currently grown will no longer be viable to grow commercially and which crops may present new opportunities for farmers. What is the role of research in helping to figure out how to change crop schemes to accommodate the changing climate? 

GARY: When people like Peter Warshall and I were associated with the office of arid land studies, we thought who cares about desert agroecology. People think they have all the water they need. Now desert agroecology is a growth industry because we’re making 40 percent of the land surface of the world into a desert. 

A team of about 20 of us are evaluating about 90 genre or groupings of plants with about 180 species. What our evaluations are telling us that mesquite and desert elderberry, and columnar cacti like saguaros and organ pipe, and understory plants like wild chilies, oregano, and wild tepary beans are going to be the crops that help us weather the extreme climatic stresses that we’re already beginning to face more so than plants that were domesticated into pampered crops.

ARTY: With the dramatic change of climate, the old knowledge may not be as useful as it used to be even for people who have been on the same land their whole life. How do we approach food production while dealing with a new set of conditions?

GARY: That’s such an interesting question, because it demands a rebalancing. It doesn’t mean the traditional ecological knowledge of Indigenous Peoples or other ethnic groups is obsolete, but we do have to drill down on the principles that underlie it. The crops may change, and they’ve always changed. Our heirloom crops have never been static. They’re dynamic. Participatory plant breeding by Indigenous People to continue to evolve their crops, to adapt them is better than abandoning traditional crops and their own knowledge. But we may need to draw on a broader reach of traditional desert knowledge because it will have implications for 40 percent of our terrestrial arable lands. 

I wrote in my books Gathering the Desert and Growing Food in a Hotter, Drier Land, about when I went and saw how the Moors or Amazigh people of Morocco and the people who live in the valley where my grandfather’s from, including my cousins on the Lebanon/Syria border are adapting their agriculture to hotter, drier conditions. In the US, we have refugees who know how to farm in deserts, but we’re disparaging them rather than welcoming them into our agricultural community. 

But there’s great exceptions to that. There’s a project in North Carolina called Transplanting Traditions that welcomes every refugee farmer who wants to land in North Carolina and adapt their knowledge to the current local markets. This issue of cultural diversity and agro-biodiversity are never two separate silos. We need the people with different ways of looking at desert farming even more than we need their desert-adapted crops. It’s not about culturally appropriating their crops and leaving them behind; those people are our future. The way that we’ve conceived what agricultural communities are through the narrow lens of the Farm Bureau is going by the wayside.

ARTY:  But crop breeding is still going to be an important element of this. Can breeding crops be bred fast enough to keep up with the changing conditions driven by climate change?

GARY: The survey that I’ve been doing with people in botanical gardens in desert institutes has identified about a third of our potential crop candidates from wild relatives of crops. 50 years ago, we didn’t have the tools to rapidly domesticate them. The Land Institute has shown that within about 15 years you can select from the wild variation in a native species and develop it into a crop.

About 30 percent of our prime candidates are in the genres like chilies, elderberry, beans, and squashes, that we have incredible diagnostic genomics. I’m not talking about genetic engineering. If we had five domesticated crops in the same genus as chilta beans or oregano or tepary beans, we would have a head start in bringing those fully into domestication. But we must not make the mistake that former plant breeders did of breeding out the secondary chemicals that have antioxidant activity or growing them in monocultures where they get diseases and pests. In polycultures with healthy communities of rich microbial allies, they will not have that degree of insect or disease infestation. 

We don’t have to do this work by ourselves. We have to think of the microbes and the pollinators as co-farmers with us, just as we think of consumers now as co-farmers with community supported agriculture projects. We don’t have to think that within the next 30 years we have to try to do all the work of the last 10,000 years. A lot of that’s already been done in related species that now, with the beauty of the Internet, we can draw on that knowledge of how other people have domesticated plants in that same plant genus. But instead of looking for one-size-fits-all crop, we’re looking at different prickly pears that fit every niche in the arid Southwest rather than one kind that goes from Taos all the way down to Las Cruces or El Paso. 

ARTY: That brings to mind the work of Salvatore Ceccarelli and the mixed varieties of wheat that he’s working with. Occidental Arts and Ecology Center and Santa Rosa Junior College are doing something similar – sowing the same field with many varieties of wheat to make sure some or most will resist stresses from extreme weather, insects, etc. The multiple varieties have a broad range of plant genetics to be able to evolve and adapt. I tasted bread from a field of a mix of 30 different species of wheat, and it was delicious. So, it seems like there’s a commercial viability to approaching things in that way.

GARY: Let’s look at that with two beautiful success stories in Arizona and our neighboring state of Sonora. First of all, with heritage grains, eight years ago we started with the oldest soft white bread wheat introduced to North America – White Sonora. It had been the major wheat grown in the Southwest until about 1950, and then with the green revolution, it was forgotten. 

I collected some of the seed of that. I harvested it and sowed it with traditional farmers, but there was no market for it. The seeds stayed with them. 

Thirty years later we had this explosion of artisanal bread makers in the Southwest, as you’ve seen in California. We looked for the desert-adapted wheats and barleys, recovered them from seed banks, and now we have eight farmers growing about 300 acres of White Sonora wheat in Arizona and Sonora.  White Sonora wheat is a low-gluten wheat. The bread, crackers, beers, and other products made from that desert-adapted wheat are in our food system every day. 

Legumes are really cereal grains just as much as grasses are. Mesquite is a legume and the most important staple food plant in the deserts for the last 8,000 years. We now have about eight hammer mills in Arizona and three more in Sonora making mesquite flour and mesquite syrup available every day of the year in many communities. We see mesquite products in coffee shops and microbreweries, in school lunches. Mesquite is an anti-diabetic staple that controls diabetes. The health benefits of these foods are part of the driving force to bring them back into our food system.

ARTY: Are there other opportunities to help face the erratic and extreme climate?

GARY: My wife and I have worked for over 20 years in the Seri Indian or Comcaac communities of Sonora along the coast of the Sea of Cortez looking out across 70 miles of water to Baja, California. Ocean level rising is radically changing their environment. Their fishing village is falling into the ocean because of sea level rising. It’s changing the configurations of marshes and estuaries that are the nursing grounds for their fish. I’m not against animal protein. I think we should get animal protein from environments like upland ranges and estuaries that we can manage better than we have in the past, in places where we can’t grow other kinds of food.

The big opportunity that we have in the coastal waters of the Sea of Cortez is open water aquaculture with adapted oysters and clams. Nearly every time that they’ve tried to bring in exotic fish or oysters from other parts of the world, they brought along diseases that have wiped it out and cost millions of dollars of losses. The Packard Foundation funded a pilot project with native oysters, scallops, and fish native to local estuaries that do extremely well even in hot, hyper-saline waters, and have great taste and great nutritional content.

We also need those coastal mangrove estuaries as buffers against the increasing frequency of hurricane fringe storms that are more intense and more frequent than ever before. They need to be the living greenbelt buffers between vulnerable coastal villages and the rising sea and greater frequency of tropical storm damage. We’re supporting a project in bringing in funders to help the Seri community do mangrove planning well beyond where the mangroves occurred over the last 100 years, to create that buffer and create broader, more stable nursery grounds. 

About 400 people in those coastal villages– based on a program we started 25 years ago of first responders for climate change food sustainability – have been employed seasonally or year-round, in sustainable fisheries and shell fish propagation that are a part of a restorative economy rather than an extractive economy. That’s a third of all the adults in those villages. The restorative economy is the second most important income now in those communities after fishing. 

I’m hopeful that we can do this in impoverished rural communities and reservation communities around the binational Southwest, but the projects have to be led by the people from those communities and the technical assistance follow their lead. In our case with the Seri, three of our former students have been tribal governors, and they call the shots. We don’t. Many of the women are teachers and have gone off to the Barefoot University in India to learn how to solarize and bring wind power into their villages, and we’re simply helping facilitate them getting to those training opportunities rather than the ideas or the leadership coming from us. 

ARTY: Your life’s work has been the celebration and integration of culture, biology, economics, and ecology. If any one of those elements are neglected, ultimately the work will not succeed.

GARY: No. The Indigenous People and the immigrants of this world – and sometimes those are one in the same groups – have been the ones most marginalized by how our current food system works. They are the ones most deserving of a better chance and a larger say in how our food systems work in the future. They have ideas and insights that if they are not recognized and given a place at the table, we will all be impoverished. Every time that we marginalize someone else on this planet, we are the ones who lose the most, because they enrich our lives and they enrich our possibilities, and we should be humbled and grateful for their presence rather than what the Trump administration did, which is marginalizing just about every ethnic group, race, persuasion, and gender that doesn’t fit a narrow definition of what is acceptable.