Why did Maya slash and burn stop?

Answer 1

The Maya of Mexico's Yucatan peninsula did not stop using slash and burn agriculture. They still use it today. Many scholars think it was the original and most common form of agriculture in the area during PreColumbian times. It was described by Diego de Landa in the mid 1500s in a book he wrote concerning Maya customs. It was also described in detail by Robert Redfield and Alfonso Villa Rojas in their book about Chan Kom, which is part of the collection of publications that came out of the Carnegie research program of the early 20th century. This agricultural system has more recently been described in Spanish by Silvia Teran and Christian Rasmussen (1994) in a book published by the State of Yucatan and DANIDA of Denmark. I also describe it in my 1998 book on Maya traditions and Mexican Rural Development. N. Bassols-Barrera and V. M. Toledo have also described it in a recent journal article.

Ideally the slash-and-burn is done cyclically, with twenty or more years of fallow between periods of two to three years of use. Maya farmers maintain that when the fallow is reduced, the yield is also reduced. However, in conditions of dense populations, farmers do not have enough land available for this cycle and thus they reduce fallow. The immediate problem of reduced fallow which has been noted by a number of researchers is weed growth. Allowing forest to grow for long periods reduces weeds (grasses etc.) on the forest floor and thus the availability of seeds that sprout and compete with the maize for nutrients when the land is cleared. The higher and denser the forest cover, the fewer weeds. Another advantage is that tree roots bring up trace minerals from the subsoil replenishing these at the level reached by maize roots. Falling leaves also contribute to soil organic matter, important for maintain tilth and soil moisture. Today, weed growth is often controlled by the application of herbicides and soil fertility is augmented by the use of fertilizers. Some weed growth is also controlled by tractor tillage.

During the 1970s and 1980s, the Mexican government introduced tractors and a version of the "Green Revolution" in those areas where the soil was sufficiently deep for tractor cultivation. Gradual compacting of soils and depletion of organic matter and changes in pH are some of the problems said to be associated with this program. Some areas cleared for tractor cultivation are no longer used for crops but rather for pasture, supplying the demands for beef and lamb among urbanites in Mexico as well as abroad.

A related issue is that in the past ten to fifteen years, the price paid to farmers for dried maize has been very low (see NAFTA). Given the costs of tractor use, hybrid seeds, herbicides and fertilisers many farmers have stopped planting in the ways recommended by Green Revolution agronomists. A few have returned to slash and burn methods, but most have abandoned farming to search for work in cities or tourist zones or in the US as agricultural workers, factory hands, or in the service sector.

Nowadays most slash-and-burn farmers are over 50, with little formal schooling and insufficient strength to be hired for construction work in cities. They provide for their families in rural communities, including their adult children and grandchildren when these are unemployed and return home. Thus, the slash-and-burn farmer is a part of the safety net of Mexican capitalism.

In addition, there are some ecological advantages to slash-and-burn. It rejuvenates forest patches and leaves a mosaic of patches in different stages of succession. These may well reduce the risk of catastrophic forest fires while helping maintain high biodiversity and thus good habitat for fauna. The impact of these fires on the local forest ecosystem has to be evaluated over time. Current government policies restrict burning, encourage mechanized agriculture and cattle raising while setting aside some protected areas for endangered species. This mix of single-purpose plots is new to the Maya forest and is an experiment. What we know to be highly resilient throughout the climate shifts of 3,000 years is Maya slash-and-burn which has not resulted in the extinction of any species of flora or fauna, to my knowledge. Although it is important to clarify that this system always included respect for certain areas of sacred forest and habitually left corridors of uncut areas between milpas of only 1 to 2 hectares. Thus forest conservation was an integral part of agriculture.

It is important to add that environmental knowledge in this area depends on use for its transfer. Farmers are also hunters and gatherers. Their wives and children participate in harvest, weeding, and gathering, and in some cases in hunting and felling brush. Gathering includes medicinal plants, plants for domestic animal use, and dead tree limbs used for cooking fires, as well as forest fruits, seeds, and roots. Farmers know the soils, which vary considerably across the peninsula. They also know well the animals they hunt and those that compete with them for their crops. In fact they plant more than they need in order to entice deer and pecarry and wild turkeys which they both feed and hunt. These are important sources of animal protein for many families. Thus, slash-and-burn is part of forest management and game management. The straight poles used to build traditional Maya houses grow best in a cleared plot allowed to fallow, not under the shade of big old trees. Palm thatch is also found in regrowing milpa plots. Regrowth occurs faster than one would imagine because the roots and trunks of trees and bushes are not removed nor are they permanently damaged by the fires. In addition, seed rain comes in from the fringes of high forest around the agricultural plots.

These are all advantages to traditional slash-and-burn which recommend it to subsistence farmers, who also tend to have traditional tastes and to not care for the hybrid maize grown with tractors and fertilizers.

As the economy has worsened, some people have left tractors and returned to slash-and-burn, as this system does not require investment in costly inputs. The harvest is free of debt. However, the biggest problem for many farmers in Yucatan today is drought and flooding, probably a result of a combination of global warming and extensive forest clearing by green revolution projects and cattle ranchers. Irrigation and drainage are critical. The regular rains of the agricultural season are now frequently interrupted by two to three week droughts which damage the forming ears of maize or kill the plants. In addition, more frequent and more intense storms are coming out of the Caribbean. These frequently flatten the maize plants in mud or rot the roots of the plants. Thus, farmers are looking more and more to irrigation systems and well drained soils. Cattle ranching has been popular but in the summer of 2009 many cattle died of hunger as there simply was not enough grass for them to eat due to the drought. Owners frequently transport water for cattle to drink during dry season but providing enough food is more difficult as droughts lengthen and spread over large areas.

Thus, the answer to this question is that the Maya continue to use their traditional slash-and-burn systems for food security despite increasing risk to all agriculture that does not include adequate irrigation and drainage. The expense of irrigation depends in large part on the depth of the water table from the surface. Drainage tends to be relatively good in the peninsula given the young karst subsoil, but the areas of flat, deep soils necessary for tractor cultivation tend to have a large percentage of clay and thus to drain more slowly than the uplands which is where traditional slash and burn is normally done.