permaculture

[Lawrence London <lfljvenaura@gmail.com>]

Investigating Chinampa
Farminghttp://www.sscnet.ucla.edu/ioa/backdirt/Fallwinter00/farming.html


Fall/Winter 00

Investigating Chinampa Farming
by Virginia Popper
Excellent preservation at CH-AZ-195 provides information on plant use and
farming activities for the two hundred years of occupation

Maize growing on chinampas

How the Aztec Empire fed the burgeoning population of its capital,
Tenochtitlan, has long intrigued researchers. Most of

Tenochtitlan’s estimated 150,000 to 200,000 inhabitants at the time of
Spanish contact were not food producers. The

system, known as chinampas, of draining swamps and building up fields in
the shallow Basin of Mexico lakebeds, was a

remarkable form of intensive agriculture that Jeffrey Parsons of the
University of Michigan suggests provided one-half to

two-thirds of the food consumed in Tenochtitlan.

At the time of Spanish contact, shallow lakes covered approximately 1000
km2 of the Basin of Mexico. Archaeological

surveys show that large expanses of the lakes were converted into
chinampas. Today the lakes are almost completely drained

and covered by urban growth, but a few pockets of chinampa agriculture
survive, including the popular tourist attraction,

the “Floating Gardens of Xochimilco.”

Several ethnohistoric and ethnographic sources describe a range of building
techniques, agricultural practices, and crops

grown on chinampas. In general, chinampas are rectangular fields 2 to 4 m
wide and 20 to 40 m long, surrounded on three or

four sides by canals. Chinampa farmers pile up layers of vegetation and mud
or dirt to raise the field surface to about 1

m above the water level.

This type of construction and the labor-intensive methods of chinampa
agriculture help overcome the main limits to

agriculture in the Basin of Mexico: variable rainfall, frosts, and soil
fertility. The proximity of the field surface to

the water table usually provides adequate soil moisture for crops. If not,
irrigation water is readily available in the

canals. The water also ameliorates nighttime temperatures, reducing the
chance of frosts. In the past, soil fertility was

maintained by periodically adding vegetation, household refuse, and
organic-rich silt dredged up from the canals to the

field surface. Among their labor-intensive practices, chinampa farmers
plant seeds in specially prepared seedbeds, later

transplanting the seedlings into the fields. In its most intensive form,
cultivation is year–round.

We know little about the origins and development of chinampa agriculture.
Although some researchers suggest that chinampa

agriculture began as early as the Formative period, around 1400 bc, no
fields have been securely dated prior to the Early

Aztec/Middle Postclassic period (ad 1150–1350). In 1981, Jeffrey Parsons
directed excavations at several archaeological

sites in the Chalco and Xochimilco lakebeds to explore the development of
chinampa agriculture.


Chinampa agriculture

My research uses plant remains excavated from an Early Aztec site
(Ch-Az-195) to address the issue of the development of

chinampa agriculture and, more specifically, to address questions about the
economy and land use at what, from its

location in the lakebed, appears to be a small hamlet associated with
chinampa farming.

Ch-Az-195 is a small mound that lies approximately 1 km southeast of Xico
Island and 1.8 km from the eastern shore of Lake

Chalco. Eight small mounds on top may be households and one larger
rectangular mound may be a public building. One

excavation unit revealed remarkably rich and finely stratified deposits
that extended down 370 cm before hitting the high

water table. This area of the site served at different times as a midden of
domestic refuse, an area of fill, and a

habitation or patio area. The unusually wet conditions in the lower
two-thirds of this excavation unit prevented the decay

of plant matter and preserved a rich array of plant remains.


Excavating Ch-Az-195

These plants represent a number of activities at the site: food production
and preparation, collection of useful weedy

plants, and craft production. Food plants include the major cultigens
(maize, beans, squash, and chile), all of which are

recorded as growing in chinampas. Fruit trees are represented by the hard
pits of Mexican cherry, Mexican hawthorn, and

prickly pear. These generally grow on the Piedmont slopes ringing the
lakes, although some may have grown on Xico Island.

The abundance of seeds from plants exploited for their edible green leaves
(quelites) show that these plants were readily

available and probably eaten. These grow as field weeds on chinampas. Many
of the plants recovered from Ch-Az-195 have

recorded medicinal uses. Various grasses and bulrush were used for baskets,
mats, and other items. Cotton (the only plant

found at the site that does not grow in the Basin of Mexico) and maguey
were used for clothing. The charcoal—primarily oak

and pine collected from the Piedmont forests—represents wood that served as
fuel, building material, and material for

canoes and tools.

The excellent preservation at Ch-Az-195 provides information on plant use
and farming activities over the approximately

two hundred­year span of the occupation. The plant remains suggest it was a
farming site rather than a mound built in the

lakebed solely for fishing or mat making. Chinampa crops occur in all
levels, and the presence of maize stalks suggests

that at least some maize was grown nearby and not imported as cobs or
kernels to the site. In addition, the abundance of

seeds from edible greens from the lowest levels of the site implies that
these common field weeds grew on fields near the

settlement or on the site. Not all of the plants, however, were necessarily
grown on nearby chinampas. Perennial fruits,

and perhaps even some crops, came from the lakeshore, the Piedmont slopes,
or Xico Island. It is unclear to what extent

the Ch-Az-195 farmers cultivated fields in these zones, collected in these
zones, and/or traded for produce from these

zones. Some evidence points to increased intensification of agriculture and
a decrease in the use of Piedmont resources

over the span of the site.


Carbonized maize cobs, maize kernels, and beans

My research examines the diversity of plant use and farming at chinampa
settlements. The data from Ch-Az-195, however, are

not representative of the entire chinampa system. Plant use and agriculture
will vary with local environmental, economic,

social, and political conditions and with the population characteristics of
a particular settlement. To document and

understand this variation, I am planning additional excavations from other
locations and time periods.


Virginia Popper is director of the Paleoethnobotany Lab at the Cotsen
Institute of Archaeology at UCLA.




-- 
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