Biomimicry

by Janine M Benyus

  Three-Story Farming in Costa Rica

  Succession is also at the heart of a Costa Rican version of Natural Systems Agriculture. The tropical forests here are paradises—cornucopias of irrepressible vegetation and edible foods ripening under a natural heat lamp and mister. It’s therefore all the more ironic, and perhaps telling, that jungles like this have made such poor sites for growing conventional crops. The first few years after clear-cutting and/or burning a primary forest, crop yields are good, but then they drop precipitously. It makes sense if you realize that the same force that creates the jungle—deluges of rain—can also leach nutrients from unprotected jungle soil after clearing, when there are no plants around to soak up water. Crop harvests also remove even more nutrients from the site. After a few years of this nutrient extortion, the soil quickly tires.

  Natural clearings in the jungle meet an entirely different fate. They are quickly revegetated by a parade of species that take over one after another, sinking roots, spreading canopies, shedding leaves, and restoring fertility to the site. Nutrients in the system are kept in play in the green growing biomass—nutrients “on the stump.”

  John J. Ewel, a botany professor at the University of Florida, Gainesville, hypothesized that if you could simulate a natural regrowth of jungle using domestic crops as stand-ins for the wild species, you could achieve the same fertility-building phenomenon and actually improve the system rather than deplete it. The trick is to start with crops that mimic the first successional stage (grasses and legumes), and then add crops that mimic the next stage (perennial shrubs), all the way up to the larger trees—nut crops, for instance.

  To test their hypothesis, Jack Ewel and colleague Corey Berish cleared two plots in Costa Rica, letting them naturally reseed to jungle. In one of the plots, every time a jungle plant sprouted, they would dig it up and replace it with a human food crop that had the same physical form. Annual for annual, herbaceous perennial for herbaceous perennial, tree for tree, vine for vine—it was as if nature were guiding the hands of the agronomists. The parade of volunteers to the natural system (Heliconia species, cucurbitaceous vines, Ipomoea species, legume vines, shrubs, grasses, and small trees) were replaced by plantain, squash varieties, yam, and (by the second or third year) fast-growing nut, fruit, and timber trees such as Brazil nuts, peach, palm, and rosewood.

  This domestic jungle of crops looked and behaved like the real jungle in the plot next door. Both plots had similar fine root surface area and identical soil fertility. The researchers also put in two control plots: a bare soil plot and a plot planted in a rotating monoculture—maize and beans followed by cassava, followed by a timber crop. While the bare soil and the rotating monoculture lost their nutrients very rapidly, the “domestic jungle” remained fertile.

  Several years before Ewel’s paper came out, British permaculturalist Robert Hart also published some concrete recommendations for cropping systems that would mimic the jungle ecosystem. They included cassava, banana, coconut, cacao, rubber, and lumber crops such as Cordia species and Swietenia species. At the end of its succession, Hart’s cropping system would be a three-tiered canopy, mimicking the structure of the jungle as well as its nutrient cycling, natural pest control, and water-purging function. The trick to keeping the soil fertile, says Hart, is to choose perennial crops with lots of leaves and roots, so they can protect the soil from hard rains, store nutrients in biomass, and put organic matter back into the soil when they shed. Hart also found it important to use plants that form symbiotic associations, as well as deep-rooted plants that pumped nutrients from different depths of the soil. In this way, the ground was kept continually covered, yields were provided throughout the year, and each set of new crops prepared the soil physically and even chemically for the next stage. Once the succession progressed to tree crops, farmers could selectively harvest timber and burn the perennials every few years to start the cycle again. Besides supporting local farmers, this sustained usefulness may also help to slow the relentless clearing of primary jungle.

  The New England Hardwood Forest

  Radical as it seems now, mirroring ecosystems is not a new concept. Sir Alfred Howard, whom many credit with the invention of organic agriculture, talked about farming to fit the land in his 1943 book, An Agricultural Testament, as did J. Russell Smith, in his 1953 book, Tree Crops: A Permanent Agriculture. Smith wanted to see eastern hillsides replanted with tree crops, which seemed to suit the hills better than the erosion-causing row crops planted after the great green wall of New World forest was torn down.

  Smith looked to the eastern deciduous forest as a model of diversity and stability. He described the great number of niches provided by the various tree-canopy levels as well as shrubby and herbaceous understories. Thanks to the diversity, he wrote, pests are kept under control and birds and browsing animals are given many places to make a living. Fine fibrous roots of woody understory plants act like a prairie’s sod to hold soil and retain nutrients. Fallen leaves and debris are slowly and steadily recycled into new plant life, preventing leaching and downslope loss of critical nutrients. The organic litter also encourages the growth of mycorrhiza—fungi that form associations with roots and further extend their water-searching power. Every now and then, wind or disease or lightning takes out a tree, creating a gap where succession and renewal can begin again.

  Early agriculture on these soils, practiced by Native Americans, was also successional in nature. The tribes practiced small-patch agriculture, raising beans, squash, corn, and tobacco on twenty-to two-hundred-acre plots. After eight to ten years, the native farmers would move on and allow the land to lie fallow. In the twenty-year hiatus before the farmers returned, succession would resume and fertility would be restored. This shifting method required tribes to be nomadic, but it mimicked the natural forest dynamism by creating small patches that were allowed to revert to forest.

  In his book, Smith bemoaned the loss of soils and productivity that occurred when white settlers began to farm more permanently on these sites, deforesting hillsides and planting row crops. The farming didn’t fit the land, he claimed. Instead, he proposed planting structural analogues—nut-and fruit-bearing trees as the only fitting crops for forest-growing land. One scheme that bore out his dream was a farm of honey locust trees (which bore seed crops) with an understory of Chinese bush clover (a perennial legume suitable for grazing and haying). This system yielded crops and supported animals, all with minimal labor, low management costs, and good weed control. He reported returns of 4,500 pounds of hay per acre per year, 2,920 pounds of honey locust nuts per acre per year on average, with a peak of 8,750 pounds of nuts per acre in eight-year-old trees.

  The features that made the hardwood forest sustainable in the wild were repeated here: a tree crop in the overstory, a stable understory to protect the soil and retain nutrients, a biological nitrogen source, and a grazing or browsing animal component. Unfortunately, Smith’s recommendations fell largely on deaf ears when his report was first issued. The fact that his work has been republished by Island Press recently, with a foreword by Wendell Berry, is a hopeful sign that the idea of nature-based farming is sprouting once again.

  The Desert Southwest

  Where prairies and forests fear to tread, the model for farming is an unlikely one—the scrubby, spiny desert of the American Southwest. Across the Sonoran, the Chihuahua, and the Mojave, rainfall is erratic and strongly seasonal, and soils may vary every few feet. These uneven conditions lead to a patchiness of vegetation—plants cluster in fertile alluvial fans, while on more barren stretches, they space themselves out to get all the water they can. Besides dividing up the space, they also divide up the season. Many species bloom and set seed only when water is available, becoming dormant as the summer blisters on.

  These strategies, which allow plants to take advantage of ephemeral resources and to endure long dry spells, were mirrored in the farming methods of original peoples who flourished here for thousands of years. The Papago and C
ocopa peoples continue to live here, gathering their foods from both wild plants and cultivated desert plants and legumes, all of which are native to the place, thus adapted to making the most of limited resources. Ethnobotanist Gary Paul Nabhan made readers aware of their agricultural practices in his book Gathering the Desert.

  To the extent possible, writes Nabhan, the Papago synchronize their agriculture with the local seasonal clock. Planting, for instance, is timed to the emergence of desert annuals—right before or after nourishing rains. By planting only on flood-watered alluvial fans, they avoid having to intensively irrigate, which in that climate of excessive evaporation would leave poisoning salt in the upper registers of the soils. Besides annuals, the Papago also sow succulents, grasses, and woody plants for food and fiber. Interspersed with the crops are wild mesquite trees, left in the fields because they can fix nitrogen and gather deeply stored soil nutrients. Long before agronomists knew why this companion planting worked, the Papago were practicing it, having taken their cue from the “genius of the place.”

  Rodale’s Regenerative Agriculture

  No talk of organic agriculture would be complete without a mention of the Rodale family, whose legacy includes the Rodale Press as well as such publications as Organic Gardening Magazine, New Farm, and Prevention, a magazine devoted to health issues. Like Mollison’s permaculture, Rodale’s “regenerative agriculture” uses biological structuring to increase the efficiency of nutrient and energy flows so that low-energy inputs are leveraged into high productivity. Succession is also used strategically. Crops are carefully chosen to change the soil flora and fauna in a way that anticipates the needs of the next crop. For instance, practitioners may plant a crop that causes the weed community to shift toward species that are not a problem for the next crop. Or they might emphasize nitrogen and soil-carbon buildup in one part of the rotation cycle to increase the productivity of subsequent crops. Finally, researchers at Rodale have spent some time, as Jackson has, looking for perennial replacements for annuals such as wheat, rice, oats, barley.

  Letting the Cows Out in the Midwest

  Crop growers are not the only ones caught in the box canyon of industrial farming. For years now, dairy farmers in the upper Midwest have been cutting hay with machines instead of letting the cows graze it. They’ve been tractoring the fifty-pound bales into their artificially lighted and heated suction-milking barns.

  Now all that is changing. Dairy farmers are opening the doors to both their minds and their barns in a nature-based movement called “grass farming.” Dairy farmers who have switched to grass farming are now letting their cows munch at least three of the five hayings in the field. They report that they enjoy the work of bringing the cows to their food rather than the other way around. Grass farmers also find that their cows are healthier and their bills are slimmer. Manure in the fields means they can pare back their fertilizer bills, and because they hay with machinery only twice, they also save money on fuel and machine wear.

  After a few years, many of the farmers are shifting to an even more natural cycle. Instead of milking their cattle year-round, they “dry them off” during the winter, so they can calve all at once in April and be ready to go back to the grass in the spring. This dry-off allows the grass farmers to do what had been unthinkable in the old system—take a vacation.

  The term grass farming signals a change in how the farmers see themselves. “They consider themselves solar harvesters now—turning sunlight into grass and then into meat and milk,” says Stephanie Rittmann, who wrote her 1994 master’s thesis (University of Wisconsin-Madison) on the swelling movement and how and why it is spreading. “What’s interesting to me is what grass farming has done to community life in the rural Midwest,” says Rittmann. “Because these farmers are trying something completely new, they are all at the entry level in terms of know-how. No one is a complete expert on managing grass pasture for their herds. In fact, one of their only guides is a book called Grass Productivity, written by French agronomist André Voisin in 1959. Beyond this, they turn to one another for advice, and have formed a long-distance support community.” They visit one another’s farms periodically to share what they’re learning and they produce a monthly newspaper called The Stockman Grass Grower that is filled with candid dialogue between producers.

  To grow good pasture, grass farmers face many of the same challenges that prairie restorers face. They begin with an alfalfa field, then sow in about four species of grass. As the years wind on, wild plants infiltrate, some that the farmers have never seen before. As Rittmann says, they are watching succession on their lands and comparing notes, learning what the land might have looked like before the plow.

  They are also using new ways to assess the health of their pasture, and here’s where the farmer becomes a naturalist. One man was at first puzzled and then absolutely thrilled to hear a strange crackling noise in his fields—the sound of hundreds of thousands of earthworm holes opening back up after a rain. “Finally I realized: That’s what a healthy pasture is supposed to sound like,” he told Rittmann. Another farmer said it took three years of grass farming before he finally heard birdsong returning to his pastures. Now he counts and catalogs the bird diversity around his pastures as a way of assessing their health. Other grass farmers look to cowpies—a cowpie in a healthy microfauna and microflora should break down in three weeks’ time in midsummer. If it’s around any longer, the farmers tell Rittmann, they start to worry.

  “What they are doing is learning how to read nature instead of simply relying on the word of a pesticide salesman,” she says. “I tell them they are starting to act like ecologists, and they just shake their heads and smile. ‘Nah. It’s just farming,’ they tell me.” Smart farming.

  RADICAL DEPARTURES: HOW DO WE GET OFF THE TREADMILL?

  The spread of the grass-farming idea should be studied carefully for clues. Just how does an idea “take” in the imagination of a group that is culturally and economically entrenched in a certain way of doing things? How will The Land Institute sell its idea to farmers who are already treading water as fast as they can just to keep up? How do you spring the mind free from its fears?

  Wes Jackson is well aware of all the things our minds have to overcome. For starters, he describes the mind shaped by reductionist science, the American experience, evolution, and affluence. “We have convinced ourselves that the universe is comprehensible in small separate pieces, that there is always more frontier, that any new technology is adaptive, and that there are, as author Wallace Stegner says, ‘things once possessed that cannot be done without.’ ” This mind conditioning makes it tough for us to think of the whole, respect nature’s limits, or pass up what technology promises, be it convenience, wealth, power, predictability, or cheap food. How, then, will the Breadbasket become a domestic prairie?

  “Not all at once,” says Piper. “We’ll begin by offering Natural Systems Agriculture as an alternative on Conservation Reserve Program lands.” The Conservation Reserve Program (CRP) was begun in 1985 to heal the hemorrhaging scars from the fencerow-to-fencerow era. Farmers are paid an average of $48 an acre to retire their erodible lands and plant them to perennial grass. So far, 36.5 million acres have been planted through CRP (if you add the land set aside in previous programs, it comes to over 100 million acres of grassy slopes). Unfortunately, many of those acres were planted in exotic grasses that are of limited use to wildlife and offer “focused” farmers (who abandoned their livestock) no way to make an income.

  Perennial polycultures on those same lands would offer farmers an income in addition to holding down their soils. They could collect their income in one of three ways. They could hay the domestic prairies, harvest the seed for human consumption, or, if they have livestock, simply graze them. This way, the income would come back to the farmer, instead of being shipped off to the manufacturers of pesticides and fertilizers. The time is right for this sort of transition, Piper feels, because the CRP is due to sunset soon, and it may not be re
newed. In a survey conducted by the Ohio Soil and Water Conservation Association, 63 percent of farmers said they were planning, for economic reasons, to plow up their CRP lands if subsidies dry up. Perhaps, if they hear about The Land Institute’s work, they can hold out for a whole new idea—that of healing the soil while growing food. To a culture accustomed to causing damage, that sounds sweet to the ear.

  But perennial polycultures won’t take over the whole farm landscape, predicts Piper. There are some noneroding bottomlands that are perfectly suitable for planting in row crops—under an organic regime, of course. “But that’s only one eighth of our cropland,” he says. “The other seven eighths consists of erodible soils and sloping ground, and it suffers when row-cropped. On these lands, Natural Systems Agriculture makes more ecological sense.” But will it make sense to farmers?

  Ultimately, the strongest persuader is likely to be changing economic conditions. When the way farmers (or anyone else, for that matter) have been doing things becomes economically uncomfortable, they will be eager to try something new. This may happen when fossil fuels begin to run out, making farm inputs such as gasoline, fertilizer, and pesticide prohibitively expensive. When that time comes, we’ll do what any species does under the pressure of change. We’ll start shopping around for alternatives and adopt the most creative one, jumping to the next evolutionary level.

  At The Land, they call this next level “the sunshine future.” If you ask, staff members will indulge in a dream of what a farm in the sunshine future would look like: The new Breadbasket farmers would tend domestic prairies—seed-producing perennial mixtures—which would build soil instead of squandering it. Because of its chemical diversity, the farm would naturally protect itself from most pests, tamping down populations before they reach epidemic levels. Weeds would be managed by the chemical interaction of plants and by shading. Nutrients would be held in the soil instead of leaching out. Pesticide and fertilizer use would be minimal, maintenance light, and plantings infrequent. A farmer could start over with a new crop of perennials every three to five years, but would do so by choice, not by necessity.