An Essay on Energetics: The Construction of the Aztec Chinampa System

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Introduction

All civilisations are dependent upon their ability to grow or access large amounts of food through exchange, trade, taxation and/or tribute. The archaeological and historical records demonstrate that hydraulic management in some form was an essential component of generating this supply (Wittfogel 1957). One form of hydraulic management involved the building of agricultural fields in low-lying swampy areas, which were otherwise unproductive and, therefore, outside the agricultural economy. This orchestrated dredging of muddy soil to form highly productive agricultural fields was practised by the Mexica, or Aztecs, of central Mexico during their imperial rule (AD 1428-1519). The fields, termed chinampas, have long been regarded as one of the most productive forms of agriculture in pre-Hispanic Mesoamerica. The most extensive region of reclamation was the swampy environs of the Chalco-Xochimilco lakebed which constituted the southern portion of Lake Texcoco (Figure 1), in close proximity to the Aztec capital of Tenochtitlan. Once this area fell under Aztec control through a series of sweeping military conquests, the orchestrated construction of chinampa fields was initiated. As a result of this reclamation project, a once agriculturally underused area was converted into the most economically productive region within the Basin of Mexico (Sanders et al. 1979; Parsons 1991).

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There are several goals for the present research. The first is to quantify, through the methodology of architectural energetics, the initial cost of construction of the Aztec chinampa system in the southern lake district. Although architectural energetics has been most frequently applied to Mayan architecture (Abrams 1994), it may be applied to intensive agricultural systems, which we deem horizontal monuments. The quantification is designed to better inform our estimates of the scale of initial construction. Sanders (1976: 131) noted that 'large areas along the lakeshore consisted of swampy land that could have been cultivated only with a considerable outlay of labour on the part of the individual farmer'. Parsons et al. (1982: 377) noted that 'the labour intensity of chinampa cultivation has never been adequately quantified, but it was certainly very demanding. Just as analyses have quantified both the labour expended in growing maize on chinampa fields (Sanders et al. 1979) and the productivity from such fields (Parsons 1976a), the current research generates baseline estimates of the scale of initial construction of the chinampa system. By doing so, we advance architectural energetic analyses by placing the quantified costs in the context of historical process, an application rarely done in archaeology (but see DeLaine 1997).

For comparative perspective, we then consider the quantified estimate of labour expended in chinampa construction relative to that expended in cloth production. Specifically, we examine the annual labour devoted to cloth production for tribute given by the Aztec village of Cihuatecpan in the Teotihuacan Valley. A major observation is that the annual allocation of labour in chinampa construction was in fact very demanding on households and that inferences regarding state imposition are well founded. We find, however, that cloth production was almost equally demanding in terms of time. Our overall conclusion is that incorporation of smaller polities into a unified Aztec state led directly to an increased level of household labour expenditure that affected all commoners, regardless of the product required wholly or in part by the state.

Environmental background to chinampa construction

The Chalco-Xochimilco drainage basin (Figure 1) is a unique environment in the highlands of Mexico. Here, adequate rainfall and prime soil conditions provide much agricultural potential (Sanders 1957: 30). Before the construction of large hydraulic control mechanisms, the Basin of Mexico contained an immense lake system. …