Terraced agriculture in the adaptation to climatic variability in the Mixteca Alta, Oaxaca, Mexico

Terrace agriculture in Latin America has existed for millennia. It is the result of local, traditional knowledge on slope management, and has adapted to social and environmental change. Agriculture is being affected by climate variability, i.e. random changes of inter-annual variation of temperature and precipitation. This variability has increased with climate change, affecting food security and increasing poverty over peasant communities that rely on rainfed agriculture. For agriculture adaptation to climate change, most research attention has been paid to agroecology and agrobiodiversity management, while the role of agriculture terracing has been less studied as an adaptation strategy. The objective of this paper was to determine how terrace management contributes to the agriculture adaptation to climatic variability in peasant communities in the Mixteca Alta, Oaxaca. Located in southeast Mexico, this is a very diverse region in terms of geology, landforms and biotic resources where terrace agriculture has been practiced for at least 3400-3500 BP. Mixteca Alta is higher than 2000 m.a.s.l., and the climate is temperate with seasonal summer rainfall. The research method was qualitative, ethnographic and participative, using semi structured interviews as primary tool. The results of interviews were grouped in four categories: climate changes and their impact on the agriculture calendar; productive systems; characteristics of terraces for agriculture; and social and economic problems of peasant communities. Interviewees indicated that the main changes have been on quality and quantity of the precipitation, specifically a decrease in total rainfall but an increase in rainfall intensity, a delayed onset of the rainy season and an early start of the midsummer heat. These changes have resulted in a delay in maize sowing and in an increase in the potential exposure of crops to frost. Early cultivation of traditional cajete maize (using residual soil moisture) in terraces was acknowledged as an efficient practice facing these changes. Interviewees recognized that terrace flat terrains, with deeper soils and higher residual soil moisture than sloping soils, allowed for coping with climatic changes and water scarcity. Cajete maize is part of the cultural heritage of the indigenous communities in this region, but is being negatively affected by a double exposure: to climate change and to adverse agricultural policies that favor large scale market agriculture and neglect family farming. However, in a context of intense climate change processes, this traditional farming practice is an important staple source for the rural population in this region.