Carlos González-Esquivel

Assessing the Sustainability of Small Farmer Natural Resource Management Systems. A Critical Analysis of the MESMIS Program (1995-2010)

Sustainability assessment oriented to improve current systems and practices is urgently needed, particularly in the context of small farmer natural resource management systems (NRMS). Unfortunately, social-ecological systems (SES) theory, sustainability evaluation frameworks, and assessment methods are still foreign not only to farmers but to many researchers, students, NGOs, policy makers/operators, and other interested groups. In this paper we examine the main achievements and challenges of the MESMIS Program (Spanish acronym for Indicator-based Sustainability Assessment Framework), a 15-year ongoing effort with impact in 60 case studies and 20 undergraduate and graduate programs mainly in Ibero-America that is attempting to cope with the stated challenges. The MESMIS experience shows that it is possible to conduct sustainability assessments in the context of small farmers through a long-term, participatory, interdisciplinary, and multi-institutional approach that integrates a solid theoretical background, a field-tested operational framework, learning tools specifically devised to facilitate the understanding of sustainability as a multidimensional and dynamic concept, and a growing set of case studies to apply to and get feedback from users. Specifically, through the dissemination of the MESMIS assessment framework in a large set of case studies in a contrasting set of social-ecological contexts, we have been able to: (a) characterize the NRMS, their subsystems, and their main interactions; (b) link attributes, i.e., general systemic properties, with sustainability indicators to assess critical socioeconomic and environmental aspects of the NRMS; (c) integrate indicators through multicriteria tools and to expose the multidimensional aspects of sustainability; (d) propose an initial multiscale assessment to articulate processes and actors at different spatial scales; (e) develop multimedia learning tools, i.e., Interactive-MESMIS, to help users understand dynamic concepts, trade-offs, and counter-intuitive behavior; and (f) promote participatory processes through role-playing games and agent-based simulation models. Key challenges are related to the need to conduct long-term longitudinal studies that fully capture system dynamic properties while at the same time actively involving relevant stakeholders through creative and lasting participative processes. We outline an improved assessment framework that should help move the program in this direction.

Environmental and socio-economic sustainability of chinampas (raised beds) in Xochimilco, Mexico City

The chinampas (raised beds) of Xochimilco, Mexico City, are highly productive, traditional wetland agricultural systems, which were able to feed most of the population in pre-hispanic times. There is a strong trend to substitute chinampas with plastic greenhouses for flower production, which creates negative impacts in the landscape, environment and culture. This study compares the environmental and socio-economic sustainability of chinampas and greenhouses, at both the farm and regional levels, using the MESMIS framework. Even though the results show that greenhouses are more profitable, the contribution of chinampas to ecosystem services cannot be substituted by greenhouses, as tree cover is lost, canals are filled and food is not provided. Greenhouses had a higher diversity, but also a higher agrochemical use and are heavily dependent on external inputs and subsidies. Chinampas have shifted from staple crops to commercial horticulture in order to remain a technically viable and economically feasible option for local farmers. However, compensation mechanisms for the provision of ecosystem services are urgently needed if this ancient system is to be maintained. The framework allowed the integration of indicators at both farm and regional scales, combining on-farm surveys with GIS techniques, which could assist in ecosystem service valuation.

Ecosystem service trade-offs, perceived drivers, and sustainability in contrasting agroecosystems in central Mexico

The ability of agroecosystems to provide food ultimately depends on the regulating and supporting ecosystem services that underpin their functioning, such as the regulation of soil quality, water quality, soil erosion, pests, and pollinators. However, there are trade-offs between provisioning and regulating or supporting services, whose nature at the farm and plot scales is poorly understood. We analyzed data at the farm level for two agroecosystems with contrasting objectives in central Mexico: one aimed at staple crop production for self-subsistence and local markets, the other directed to a cash crop for export markets. Bivariate and multivariate tradeoffs were analyzed for different crop management strategies (conventional, organic, traditional, crop rotation) and their underpinning socioeconomic drivers. There was a clear trade-off between crop yield and soil quality in self-subsistence systems. However, other expected trade-offs between yields and soil quality did not always occur, likely because of the overall good soils of the region and the low to medium input profile of most farms. Trade-offs were highly dependent on farm-specific agricultural practices; organic, traditional, and rotation management systems generally showed smaller trade-offs between yield and soil quality, pest control, and biodiversity than did conventional management systems. Perceived drivers reported by farmers included increasing prices for cash crops, rising costs of inputs, and extreme climatic events (e.g., drought, hail, frost). Farmers did not identify the regulation of soil quality, water quality, soil erosion, pests, or pollinators as important constraints. Although acceptable yields could be maintained irrespective of key regulating and supporting services according to these perceptions, current levels of soil erosion and nutrient runoff are likely to have important negative effects at the watershed scale. Sustainability in both agroecosystems could be increased substantially by promoting alternative practices aimed at maintaining biodiversity, soil quality, and soil retention.

Biotic interactions in the rhizosphere in relation to plant and soil nutrient dynamics

The rhizosphere is the interface between roots and the soil where nutrient absorption for plant growth in agroecosystems is facilitated. An abundant and diverse rhizosphere biome is involved in biogeochemical processes, including bacteria, fungi and soil fauna, driving soil C, N and P dynamics. Plant carbon photosynthates allocated to the root and rhizosphere are priming microbial activities important for plant nutrition such as organic matter decomposition, P solubilization, N fixation, mycorrhizal nutrient transport and biocontrol of root pests. While substantial information is available on the role of individual groups of the rhizosphere microbiome in biogeochemical processes, less attention has been given to the interactions between different beneficial rhizosphere microorganisms. Also, interactions between soil fauna and rhizosphere microorganisms still remain relatively unexplored. In order to improve our knowledge on the role of the rhizosphere in C, N and P biogeochemical processes a more holistic and functional approach is required. In this review, state of the art information on the role of biotic interactions in the rhizosphere on C, N and P biogeochemical processes relevant for plant nutrition in agroecosystems is presented.

Back to the roots: understanding current agroecological movement, science, and practice in Mexico

ABSTRACT In the middle of the last century, there were two types of agronomic scientists in Mexico. One group perceived traditional agriculture as backward and in need of modernization with advanced technologies. The other group, engaged in intensive fieldwork, studied and found inspiration in peasant and indigenous systems. This latter group of researchers who studied and described the biocultural richness of these systems provided the foundations for the development of agroecology in Mexico. Mexican indigenous systems also inspired many of the pioneers of agroecology at the global level. In this review, we strive to describe the historical landmarks of the development of agroecological education and research in the past and present in Mexico, while elaborating on the challenges that this discipline faces today and in the future.