ABSTRACT. Three case studies from Mexico are presented in which the impacts of the recent introduction of jatropha cultivation for biodiesel production are examined. In Chiapas and Michoacan, local social and environmental impacts were assessed using interviews with key informants and questionnaires directed at three groups of stakeholders: jatropha cultivators, farmers in the same areas who are not cultivating jatropha, and laborers on jatropha farms. Results show that the farmers are primarily motivated to participate by the subsidies offered in a government program in the first 2 years, rather than any proven economic benefit. Our farm budget study indicated that profits would be marginal for these farmers. However, no cases of land alienation were involved, and impacts on food security and deforestation are currently not significant. Employment opportunities for landless laborers have increased in areas where jatropha is now grown. The program is only in its third year currently, so these outcomes would need to be reexamined as it develops. In Yucatan, production is mainly in the hands of commercial companies, using estates formerly under low-intensity grazing and secondary forest. A carbon balance analysis indicated that there may be a significant loss of carbon stocks associated with jatropha plantation establishment on these estates. Depending on the maturity of the forest regrowth and the intensity of jatropha production, the carbon payback period varies from 2 to 14 years, although, in some scenarios, the carbon debt may never be recovered.
This study aims to answer the question if and how biofuels can be produced in Mexico without aggravating water scarcity, reducing greenhouse gas (GHG) emissions and avoiding indirect land-use changes. We analyzed environmental impacts of six potential maize-bioethanol production systems in Mexico on water resources, land use, and GHG emissions by using a life cycle assessment approach. Three irrigated high-input maize systems and three rain-fed low-yield systems were analyzed. Inventory data was acquired by soil sampling and interviews with farmers. For the water footprint, fi eld water balances were modeled using the Food and Agriculture Organization (FAO) AquaCrop Model. For the carbon footprint, the BioGrace tool was used. Based on the results of status-quo analysis, scenarios with improved agricultural management were defi ned to identify optimization potential. Additionally, the producible amount of biofuels was estimated on a national level. The analyses showed that improving management in rain-fed agriculture offers the best opportunities for biofuel production without compromising regional water availability and without unwanted indirect effects on food prices and GHG emissions. Around 3.4% of Mexican gas consumption could be produced from maize bioethanol in Mexico without the above mentioned unwanted effects. By optimizing green water use in rain-fed maize production, around 3 billion m 3 of non-productive soil evaporation would be put into productive use. This is around 10% of the total water extracted from aquifers in Mexico. From this we conclude that unproductive soil evaporation is an underestimated water resource which should be considered in water management.
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