By Ronnie Cummins
“Unsustainable land use and greenhouse gas emissions are delivering a one-two punch to natural ecosystems that are key to the fight against global climate change. And without sweeping emissions cuts and transformations to food production and land management, the world stands no chance of staving off catastrophic planetary warming.” (HuffPost, based on UN report)
Agave plants (the best known of which are blue agave, used to produce tequila), along with the nitrogen-fixing, often shrubby, companion trees such as mesquite, huizache, desert ironwood, wattle, and varieties of acacia that readily grow alongside agave, are among the most common, prolific, and yet routinely denigrated or ignored plants in the world. As India climate scientist Dr. Promode Kant points out:
“Agave is to the drier parts of the world what bamboo is to its wetter zones. Capturing atmospheric CO2 in vegetation is severely limited by the availability of land and water. The best choice would be species that can utilize lands unfit for food production and yet make the dynamics of carbon sequestration faster. As much as 40% land on earth is arid and semi-arid, largely in the tropics but also in the cool temperate zones up north. And on almost half of these lands, with a minimum annual rainfall of about 250 mm and soils that are slightly refractory, the very valuable species of agave grows reasonably well.” (Kant, P. 2010)
Agave plants and nitrogen-fixing trees densely intercropped and cultivated together have the capacity to draw down massive amounts of CO2 from the atmosphere and produce more above ground and below ground biomass (and fermented animal fodder) on a continuous year-to-year basis than any other desert and semi-desert species. Ideal for arid and hot climates, agaves and their companion trees, once established, require little or no irrigation to survive and thrive. Agaves alone can draw down and store above ground the dry weight equivalent of 30-60 tons of CO2 per hectare (one hectare equals 10,000 square meters or 2.47 acres). These naturally adapted succulents and deep-rooted trees are also basically impervious to rising global temperatures and drought.
Now, a new, agave-based agroforestry and livestock feeding model developed in Guanajuato, Mexico promises to revitalize campesino/small farmer livestock production while storing massive amounts of atmospheric carbon above ground. Scaled up on millions of currently degraded and overgrazed rangelands, these agave/agroforestry systems have the potential to not only improve soil health and pasture, but to enable countries like Mexico and regions like the Southwestern US (in conjunction with a transition to renewable energy) to achieve “net zero” greenhouse gas emissions over the next decade.
As international scientists, activists, and our own everyday experience tell us, we are facing a Climate Emergency. A “profit at any cost,” fossil fuel-supercharged economy, coupled with industrial agriculture and factory farms, destructive land use, and mindless consumption have pumped a dangerous load of CO2 and greenhouse gas pollution into the sky, bringing on global warming and violent climate change. Degenerative food, farming, and land use practices have de-carbonized and killed off much of the biological life and natural carbon-sequestering capacity of our soils, forests, and ecosystems. This degradation and desertification of global landscapes has oxidized and released billions of tons of greenhouse gases into the atmosphere, and eliminated much of the above ground biomass once stored in our forests and landscapes. This global degeneration has depleted so much of the carbon and biological life in our soils, trees, and plants that these natural systems can no longer draw down and sequester (through natural photosynthesis) enough of the excess CO2 and greenhouse gases in the atmosphere to maintain a balanced carbon cycle (between the atmosphere and terrestrial ecosystems) and stable climate.
The United Nations Convention to Combat Desertification (UNCCD) estimates that arid and semi-arid lands make up 41.3% of the earth’s land surface, including 15% of Latin America (most of Mexico), 66% of Africa, 40% of Asia, and 24% of Europe. Farmers and herders in these areas face tremendous challenges because of increasing droughts, erratic rainfall, degraded soils, overgrazed pastures, and water scarcity. Many of these areas are in danger of degenerating even further into desert, unable to sustain any crops or livestock whatsoever. To save ourselves from climate catastrophe we have no choice but to work with farmers and traditional communities to figure out how we can quickly restore these billions of acres of degraded drylands, greening and shading the desert and exponentially increasing the amounts of atmospheric carbon stored above ground and below ground in these areas.
Most of the world’s drylands are located in the economically under-developed regions of the Global South, although there are millions of acres of drylands in the US, Australia, and Southern Europe as well. Farming, ranching, and ecosystem conservation are becoming increasingly problematic in these drylands, especially given the fact that the majority of the farms and ranches in these areas do not have irrigation wells or year-round access to surface water. Poverty and civil strife are rampant. Crop and livestock production levels (unless irrigated) are deteriorating, trees and perennials have typically been removed or seasonally burned, and pastures and rangelands have been overgrazed.
The good news, however, coming out of Mexico, applicable to many other regions, is that if farmers and ranchers can stop overgrazing pastures and rangelands, eliminate slash and burn practices; and instead reforest, revegetate, rehydrate, and re-carbonize depleted soils, integrating traditional and indigenous water catchment, agroforestry, livestock, and land management practices, we may well be able to sequester a major portion of the excess atmospheric carbon dioxide that has destabilized the climate and made survival for the world’s 500 million smallholders and three billion rural residents increasingly difficult.
Although our “house is on fire” as Swedish climate activist Greta Thunberg warns us, now is not the time to give up hope. We still have time to turn things around, if we can carry out, to quote the IPCC, “sweeping emissions cuts and transformations to food production and land management…” Unleashing the power of agave and nitrogen-fixing trees is one way we can do this.
After decades as a food, farm, anti-GMO, and climate campaigner for the Organic Consumers Association in the US, I now spend a good part of my time managing an organic and regenerative farm and training center, Via Organica, in the high-desert, Bajio drylands of North Central Mexico. The semi-arid, temporal (seasonal rainfall) ecosystem and climate in the state of Guanajuato is similar to what you find in many parts of Mexico, and in fact in 40% of the world. In our valley, we typically get 20 inches or 500 millimeters of precipitation in the “rainy season” (July-October), greening the landscape, followed by eight months with little or no rain whatsoever.
At Rancho Via Organica, we’ve been trying to regenerate our high-desert (6300 feet elevation) environment, developing farming, livestock, and landscape management practices that produce healthy organic food and seeds, sequester carbon in the soil, preserve our monte or natural densely-vegetated areas, slow down and infiltrate rainwater (including runoff coming down the mountains and hillsides) to recharge our water table, and reforest and revegetate our still somewhat degraded corn fields and pasturelands. Looking across our mountain valley, the most prominent flora are cactus and agave plants (some of which are quite large) along with hundreds of thorny, typically undersized, mesquite, huizache, and acacia shrubs/trees. In order to grow our vegetable and cover crops, maintain our olive, mulberry, citrus, and pomegranate trees, and provide water and forage for our animals, we like most small farmers and ranchers in Mexico, irrigate Via Organica with only the rainfall that we can collect and store in cisterns, ponds, and soils. Eighty-six percent of Mexican farmers and herders have no well or source of irrigation, other than seasonal rainfall, and therefore struggle to grow their milpas (corn, beans, and squash) and raise their animals in their arid or semi-arid landscapes.
Greening the Drylands: A New Agroforestry Model
Recently Dr. Juan Frias, a retired college professor and scientist, came up to me after attending a workshop at our farm. As we discussed regenerative agriculture, soil carbon sequestration, and climate change, Juan told me about a new system of drylands agroforestry and livestock management (sheep and goats), based upon agave plants and mesquite trees in the nearby community of San Luis de la Paz. They call their agroforestry system Modelo Zamarripa.
By densely planting, pruning, and inter-cropping high-biomass, high-forage producing, fast-growing species of agaves (1600-2000 per hectare) amongst preexisting deep-rooted, nitrogen-fixing tree species such as mesquite, or amongst tree seedlings, (supplemented with fermented agave/mesquite silage), these farmers are transforming their landscape and their livelihoods.
As part of their agroforestry or silvopasture system, the Zamarripa farmers integrate rotational grazing of sheep and goats across their ranch, supplementing the pasture forage their animals consume with fermented silage. The fermented forage also appears to provide an excellent silage for other livestock as well, including cattle, pigs, and chickens.
The revolutionary innovation of these farmers has been to turn a heretofore indigestible, but massive and accessible source of biomass, the agave leaves, into a valuable animal feed, using the natural process of fermentation to transform the plants’ indigestible saponin and lectin compounds into digestible carbohydrates and fiber. To do this they have developed a relatively simple machine, hooked up to a tractor, that can chop up the very tough leaves of the agave. After chopping the agave they then anerobically ferment large quantities of the plant’s otherwise indigestible leaves (ideally along with the protein-rich pods of the mesqiuite tree) in a closed container. The fermented end-product, after 30 days, is a nutritious but very inexpensive silage or animal fodder, that costs less than one Mexican peso (or five cents US) per kilo to produce. According to Dr. Frias, lambs readily convert ten kilos of feed into one kilo of body weight. At less than 5 cents per kilo (2.5 cents per pound) this forage can make the difference between survival and bankruptcy for the tens of millions of the world’s small farmers and herders.
The Zamarripa system of drylands afforestation and silvopasture generates massive amounts of plant biomass on a continuous basis, improves soil fertility, rejuvenates grass and forage on previously overgrazed rangelands, and meanwhile draws down massive quantities of CO2 from the atmosphere. One scientist estimates that certain varieties of agave can produce up to 43 tons per hectare of dry weight biomass per year, on a continuous basis (Kant, 2010). Other agronomists have told me that high-biomass varieties of agave should do well wherever any type of agave are already growing.
Species of agave and complementary nitrogen-fixing trees such as mesquite can be found in most arid and semi-arid regions of the world. Mesquite grows readily not only in Texas and the Southwestern US, Mexico, Central America, Argentina, Chile, and other Latin American nations, but also “thrives in arid and semi-arid regions of North America, Africa, the Middle East, Tunisia, Algeria, India, Pakistan, Afghanistan, Myanmar (Burma), Russia, Hawaii, West Indies, Puerto Rico and Australia.” (Ramos, 2007)
Along with a growing number of farmers and agronomists, I believe that this new agroforestry and holistic grazing system has the potential to be a game-changer, to draw down and sequester millions of tons of excess atmospheric carbon into soils and aboveground plant and tree biomass every year, while producing massive amounts of fermented animal feed and raw materials for alcoholic beverages, fiber, wood, fuel, and and biochar from the agave plant and its companion trees.
At Via Organica, outside San Miguel de Allende, Guanajuato, we are utilizing moveable, solar-fenced paddocks for our grazing sheep and goats in order to protect tree seedlings, prevent overgrazing or under-grazing, eliminate dead grasses and invasive species, and to concentrate animal feces and urine across the landscape in a controlled manner. At the same time that we are rotating and moving our livestock on a daily basis, we are transplanting, pruning, finely chopping (by machine), and fermenting (in closed containers) the heavy biomass leaves or pencas of the agave salmiana plants. Some individual agave pencas or leaves can weigh (wet) as much as 40 kilos or 88 pounds.
The bountiful harvest of this regenerative, high-biomass, high carbon-sequestering system includes not only extremely low-cost, nutritious animal forage, but also high-quality organic lamb, mutton, cheese, milk, aquamiel (agave sap), pulque (a mildly alcoholic beverage) and distilled agave liquor (mescal), all produced organically with no synthetic chemicals or pesticides whatsoever, at affordable prices, with excess agave biomass and fiber available for textiles, compost, biochar, and construction materials.
Massive Potential Atmospheric Carbon Drawdown
From a climate crisis perspective, what is Earth-shaking is the enormous impact that this agroforestry system, scaled up widely on the Earth’s arid and semi-arid lands, can have on mitigating and eventually reversing global warming. Forty-three tons of above ground dry weight biomass production on a continuing basis per hectare per year ranks among the highest rates of drawing down and storing atmospheric carbon in the world, apart from intact old-growth and tropical rainforests. Imagine the carbon sequestration potential if rural farmers and pastoralists can establish agave-based agroforestry systems over the next decade on just 10% of the worlds five billion degraded acres (500 million acres), areas unsuited for crop production but areas where agave plants and suitable native nitrogen-fixing companion tress (such as acacia varieties in Africa) are already growing, or could grow. Conservatively estimating an above ground biomass carbon storage rate of 10 tons of carbon per acre per year on these 500 million acres, (counting both agave and companion trees, aboveground and below ground biomass) we would then be able to cumulatively sequester five billion tons of carbon (18 billion gigatons of CO2e) from the atmosphere every year. Five billion tons of additional carbon sequestered in the Earth’s soils and biota equals nearly 50% of all human Greenhouse Gas emissions in 2018.
The Power of an Agave-Based Agroforestry System
To better understand the potential of this agroforestry/holistic grazing system, a little more background information on agave plants, and nitrogen-fixing or trees such as mesquite, huizache, or other fodder and food producing trees such as moringa may be useful. Various varieties of agave plants (along with their cactus relatives and companion nitrogen-fixing trees) are found growing on approximately 20% of the earth’s lands, essentially on the half of the world’s drylands where there is a minimum annual rainfall of approximately 10 inches or 250 mm, where the temperature never drops below 14 degrees Fahrenheit. One scientist has described the tremendous biomass production and carbon-storage potential of agaves in dry areas:
“Agave is to the drier parts of the world what bamboo is to its wetter zones. Capturing atmospheric CO2 in vegetation is severely limited by the availability of land and water. The best choice would be species that can utilize lands unfit for food production and yet make the dynamics of carbon sequestration faster…[A]gave can … be used for carbon sequestration projects under CDM [the Clean Development Mechanism of the Kyoto Climate Protocol] even though by itself it does not constitute a tree crop and cannot provide the minimum required tree crown cover to create a forest as required under CDM rules. But if the minimum required crown cover is created by planting an adequate number of suitable tree species in agave plantations then the carbon sequestered in the agave plants will also be eligible for measurement as above ground dry biomass and provide handsome carbon credits. This makes agave an excellent CDM crop for bioethanol as well as for afforestation over poor quality arid lands giving both permanent carbon credits for bioenergy and temporary credits of forestry for carbon sequestration. It causes no threat to food security and places no demand for the scarce water and since it can be harvested annually after a short initial gestation period of establishment, and yields many products that have existing markets, it is also well suited for eradication of poverty…”(Kant, 2010).
Agaves, of which there are 200 or more varieties growing across the world, can thrive even in dry, degraded lands unsuitable for crop production because of their Crassulacean Acid Metabolism (CAM) photosynthetic pathway (cacti and other related desert plants also have a CAM pathway) that essentially enables these plants to draw down moisture from the air and store it in their thick tough leaves during the nighttime, while the opening in their leaves (the stomata) close up during daylight hours, drastically reducing evaporation. Meanwhile its relatively shallow roots below the soil surface spread out horizontally, taking in available moisture and nutrients from the topsoil, especially during the rainy season. In addition, its propagation of baby plants or pups, (up to 50 among some varieties) that grow out of its horizontal roots makes the plant a self-reproducing perennial, able to sustain high biomass growth, and carbon-storage and sequestration on a long-term basis. Even as a growing agave plant is pruned beginning in year three (to produce fermented silage) and the entire mature agave plant (the pina) is harvested at the end of its lifespan, in order to make mescal, in our case after 8-10 years, it leaves behind a family of pups that are carrying out photosynthesis and producing biomass (leaves and stem) at an equal or greater rate than the parent plant. In other words, a very high level of above ground carbon storage and below ground sequestration (10-17 tons of carbon sored per acre) can be maintained year after year. All with no irrigation, and no synthetic fertilizers or chemicals required, if intercropped in conjunction with nitrogen-fixing tree such as mesquite, huizache, moringa, or other dryland species such as the acacias that grow in arid or semi-arid areas.
Agaves and a number of their tree companions have been used as sources of food, beverage, and fiber by indigenous societies for hundreds, in fact thousands of years (Álvarez-Fuentes et al, 2015). However, until recently farmers had not been able to figure out how to utilize the massive biomass of the agave plant leaves, which, unless they are fermented, are basically indigestible (filled with saponins and lectins) and even harmful to livestock. In fact, this is why, besides the thorns and thick skins of the leaves, animals typically will not, unless starving, eat them. According to Dr. Juan Frias, once their massive leaves (which contain 30% sugar) are chopped up and fermented in closed containers, after a short period of adjustment, grazing animals (pigs and poultry) will gobble up this sweet, nutritious forage like candy.
Developing a native species/agroforestry/livestock system on 5-10 million acres of land unsuitable for food crops in a large country like Mexico (which has 357 million acres of cropland and pastureland, much of which is degraded) could literally sequester 37-74% of the country’s net current fossil fuel emissions (current net emissions are 492m tons of CO2e). Moreover, in a number of other nations with extensive arid and semi-arid lands, and lower GHG emissions than Mexico, it’s possible that some countries could literally reach net zero emissions utilizing similar drylands agroforestry systems. And of course wherever these agave/agroforestry/holistic grazing systems are deployed, farmers and ranchers will also be restoring the fertility and moisture holding capacity of millions/billions acres of pasturelands and rangelands, thereby promoting rural food self-sufficiency and prosperity.
Scaling up best regenerative practices on the world’s billions of acres of croplands, pasturelands, and forest lands—especially those degraded lands no longer suitable for crops or grazing can play a major role, along with moving away from fossil fuels to renewable energy, in stopping and reversing climate change.
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