Ecosystem ecology and sustainability in the Chinampa raised-field agriculture of Mexico City

Jorge Federico Miranda Velez

Studenteropgave: Speciale

Abstrakt

This thesis presents an analysis of the prehispanic and modern chinampas of central Mexico through the lens of ecosystem ecology and soil science, aimed at gauging the actual richness and sustainability of this agricultural practice. To do so, it makes use of historical accounts and modern archaeological findings to reconstruct a cohesive conceptual model of what the Chinampa agricultural system, as well as the chinampa raised fields themselves, likely looked like in the late 15th century A.D. Onto this conceptual model, the Chinampa’s original ecosystem ecology is overlaid by calculating pools and fluxes of carbon, nitrogen and phosphorus from known aspects of this agricultural system; and where detailed ecological knowledge is lacking, historical accounts and parallel ecosystems are brought in to fill in the gaps through extrapolation and inference.
These conceptual models and theoretical nutrient cycles are brought closer to the ground by the combination of field work performed in the late 2017 and early 2018 in the extant chinampas of Xochimilco, Mexico, and subsequent laboratory analyses of soil and sediment samples collected in the field.
The analyses, performed at Roskilde University in Denmark, focus around the quantification of carbon, nitrogen and phosphorus in the soil of the extant chinampas and sediment from the modern canals of Xochimilco.
Firstly, total carbon, nitrogen and phosphorus, as well as extracted nitrate and ammonium, were quantified in samples from a series of soil cores 1 m deep. Secondly, an experiment was carried out to estimate the biogeochemical changes in the canal sediment often used as soil amendment, a practice known as mucking. This experiment was run twice, once for 21 days and once for 64 days, and sediment samples were later analysed for total carbon and nitrogen, as well as nitrate and ammonium content and total, inorganic and Olsen phosphorus.
Finally, making use of the experimental results obtained and literature centred on the study of the present-day chinampa landscape, a new conceptual model and ecosystem ecology are discussed in a manner that considers present socio-environmental conditions and current agricultural practices that in the modern Chinampa landscape.
This thesis concludes with recount of the most important ecosystem processes and agricultural practices that can have important roles in the sustainability, and ultimately the survival, of Chinampa agriculture in Mexico.

UddannelserMiljørisiko, (Bachelor/kandidatuddannelse) Kandidat
SprogEngelsk
Udgivelsesdato29 aug. 2018
Antal sider85
VejledereNiels H. Jensen

Emneord

  • Chinampa
  • Nutrient cycle
  • Carbon
  • Nitrogen
  • Phosphorus
  • Agroecology