it was already almost noon, and the sun beat down like a cudgel.  the forest was silent except for the incessant band saw buzz of a cicada.  i picked up a limestone block from a tangle of tree roots and studied it as i rested at the side of the trail.  earlier that morning, i had arrived in lacanja chansayab, a small lacandon maya community in the heart of the lacandon rainforest of chiapas, mexico.  it was also near the center of the maya empire which once dominated mesoamerica.  the brick i held was almost certainly a remnant of one of the hundreds of ruins that dotted this landscape.  a millennium ago, these sites glittered white in the sun, contrasting the dark green of the rainforest.  over the centuries, the forest reclaimed them and tore many down brick by brick. 

historians once thought the lacandon were the direct descendants of the maya who built these now-ruined palaces and pyramids.  while the lacandon are certainly maya, the romantic theories of 20th century scholars have been largely disproven.  recent archaeological and anthropological evidence suggests they descended from several maya groups which sheltered together in the lacandon rainforest to escape the spanish conquistadors.  but while the ancient maya edifices have crumbled, other aspects of their life have remained intact. lacandon maya culture is expressed, in part, in their cultivation of traditional forest gardens.  these agroforests, probably based in large part on the agroforestry management of the ancient maya, allow them to conserve the surrounding tropical wet forest while still obtaining the resources they need.

entering a forest garden, or milpa, can be overwhelming, as it does not resemble gardens with neatly spaced rows of vegetables.  towering corn blocks out the sky.  squash vines sprawl across the ground.  bean plants spiral up cornstalks.  small trees dot the milpa, blurring the boundary between the forest and the garden.  despite seeming chaotic, the lacandon milpa is carefully designed; each crop plays a role. 

corn is the primary milpa crop.  in one of many maya creation myths, a pair of twins defeating the lords of the underworld, allowing their father to be reborn from his earthen tomb as maize.  thus, maize is the first father of the maya‒the wellspring of humanity.  the energy stored in corn kernels planted in little pits, like miniature earthen tombs, is channeled into vertical growth after germination.  this rapid growth requires a large amount of nutrients, especially nitrogen.  left alone, the corn’s growth plateaus in short order so lacandon famers apply their knowledge of environmental processes to solve the problem of nitrogen limitation. 

nitrogen is the most abundant gas in the atmosphere, but plants cannot utilize it to develop new tissues.  to overcome this, lacandon farmers plant leguminous beans near the corn.  legumes have a symbiotic relationship with rhizobium bacteria.  rhizobium can convert nitrogen gas to chemical forms plants can utilize.  unfortunately, the enzymes it uses to perform this conversion cannot function in the presence of oxygen.  so, legumes form a nodule around the bacteria to provide an oxygen-free workplace to repay the favor.  rhizobium then deposits the biologically available forms of nitrogen in nearby soil.  in turn, corn provides a trellis for the beans to reach higher for sunlight in return for the gift of nitrogen. 

squash completes the trinity.  the squash’s leaves shade the ground as a token of gratitude for the beans’ nitrogen, retaining soil moisture and shading weeds that might try to take advantage of the nitrogen-enriched soil. 

while corn, squash, and beans are the main three milpa crops, lacandon farmers plant dozens of crop species in their milpas, having developed a thorough ecoagricultural knowledge over centuries of observation and experimentation.  they burn vegetation to deposit carbon into patches of soil near tomatoes.  they plant moisture-tolerant crops like chayote in areas that pool water.  rather than removing trees which may shade out milpa crops, some are allowed to grow to attract birds and pollinators. 

milpa production eventually depletes soil nutrients, so lacandon farmers halt crop cultivation and leave it to become fallow.  lacandon farmers continue to manage these fallows by planting and clearing areas around desirable plants.  they even pin branches against timber trees so their grain stays straight, creating a sort of bonsai.  eventually, and in no small part due to the management of lacandon farmers, forests reclaim these fallows and soil nutrient levels recover.  at this point, the stand can be cleared and replanted as a milpa or left as a forest.

i dropped the brick and continued through the forest, which probably was a long-abandoned milpa. just as lacandon farmers care for their land, the milpa and forest care for the lacandon.  milpa crops provide plentiful and nutritious food.  fallows permit the lacandon gather medicinal and edible plants, cut timber and firewood, fish in streams, and hunt for wild game.   such indigenous cultures live still directly rely upon the land.  their ecosystem management conserves the environment by maintaining biogeochemical cycling and biodiversity.  they are both ecologically sustainable and productive, guaranteeing subsistence and preserving natural resources for future generations.  

a few miles away, farmers and ranchers are clearing the lacandon rainforest at an annual rate of five percent to raise corn and cattle commercially.  this form of agriculture is a war of attrition on the land: felling any trees that might shade crops, controlling weeds with harmful herbicides, spraying pesticides that kill any insect that might steal some yields, and dumping chemical fertilizers that leach into and pollute nearby water.  agriculture can be one of the most intimate ways in which we connect with nature, but industrial agriculture deforms this covenant by abusing land.  sustainability is forsaken in the name of profit.  indigenous cultures, like the lacandon, recognize that land is more than a source of resources we need to live; it is life itself.  perhaps they can teach us that our relationships with nature, including agriculture, must be based on reciprocity and goodwill rather than exploitation and control.