Agaves basically require no irrigation, literally drawing moisture directly from the air and storing it in their thick thorny leaves (pencas) and stem or heart (piña) utilizing their Crassulacean Acid Metabolism (CAM) photosynthetic pathway, which enables the plant to grow and produce significant amounts of biomass, even under conditions of severely restricted water availability and prolonged droughts. Agaves reproduce by putting out shoots or hijuelos alongside the mother plant, (approximately 3-4 per year) or through seeds, if the plant is allowed to flower at the end of its 8-13 year (or more) lifespan.
A number of agave varieties appropriate for drylands agroforestry (salmiana, americana, mapisaga) readily grow into large plants, reaching a weight of 1400 pounds to one ton in the space of 8-13 years. Agaves are among the world’s top 15 plants or trees in terms of drawing down large amounts of carbon dioxide from the atmosphere and producing plant biomass. Certain varieties of agave are capable of producing up to 17 tons of biomass per acre or more per year on a continuous basis. In addition, the water use of agaves (and other desert-adapted CAM plants) is typically 4-12 times more efficient than other plants and trees, with average water demand approximately 6 times lower.
Agave’s nitrogen-fixing, deep-rooted companion trees or shrubs such as mesquite and acacias have adapted to survive in these same dryland environments as well. From an environmental, soil health, and carbon-sequestering perspective, agaves should be cultivated, not as a monoculture, as is commonly done with agave azul (the blue agave species) on tequila plantations in Mexico (often 1200-1600 plants per acre), but as a polyculture. In this polyculture agroforestry system, several varieties of agave are interspersed with native nitrogen-fixing trees or shrubs (such as mesquite or acacias), pasture grass, and cover crops, which fix the nitrogen and nutrients into the soil which the agave needs to draw upon in order to grow and produce significant amounts of biomass/animal forage. If grown as a polyculture, agaves and their companion trees and shrubs can be cultivated on a continuous basis, producing large amounts of biomass and sequestering significant amounts of carbon above ground and below ground, without depleting soil fertility or biodiversity.
In addition to these polyculture practices, planned rotational grazing on these agroforestry pastures not only provides significant forage for livestock, but done properly (neither overgrazing nor under-grazing), further improves or regenerates the soil, eliminating dead grasses, invasive species, facilitating water infiltration (in part through ground disturbance i.e. hoof prints), concentrating animal manure and urine, and increasing soil organic matter, soil carbon, biodiversity, and fertility.
Although agave is a plant that grows prolifically in some of the harshest climates in the world, up until now this plant has been largely ignored, if not outright denigrated. Apart from producing alcoholic beverages, agaves are often considered a plant and livestock pest, along with its thorny, nitrogen-fixing, leguminous companion trees or shrubs such as mesquite and acacias.
Moving beyond conventional monoculture and chemical-intensive farm practices, and combining the traditional indigenous knowledge of native desert plants and natural fermentation, an innovative group of Mexico-based farmers have learned how to reforest and green their drylands, all without the use of irrigation or expensive and toxic agricultural inputs.
They have accomplished this by densely planting, pruning, and inter-cropping high-biomass, high-forage producing species of agaves (average 2000 per hectare, 810 per acre) among pre-existing deep-rooted, nitrogen-fixing tree or shrub species (500 per hectare) such as mesquite and acacia, or alongside transplanted tree seedlings. These agaves naturally produce large amounts of plant leaf which can then be chopped up and fermented, turned into silage. Agave’s perennial silage production far exceeds most other forage production (most of which require irrigation and expensive chemical inputs) producing approximately 40 tons per acre of fermented silage, annually.
The agave silage of the three most productive varieties has a considerable market value of $100 US per ton (up to $4,000 US per acre gross profit, with 50% of this amount being net profit after subtracting production and labor costs). This system, in combination with rotational grazing, has the capacity to feed up to 60 sheep, lambs or goats per acre/per year. Once certified as organic, lamb production can easily increase net profits to $5,000 US per acre annually.