Environmental Impact of Intensive Cultivation of Blue Agave
Intensive Cultivation by the Tequila Industry
In 1999 there were over 90,000 acres of Blue Agave under cultivation in Guadalajaa Mexico and the Tequila industry has grown substantially since then (Valenzuela 2011; Mohr 1999). Growth has been especially strong in the last 15 years, leading to a 19.82% annual increase in the industry between 1995 and 2008 (Valenzuela 2011). As a result, cultivation has been intensified and industrialized leading to the danger of erosion in germplasm diversity among agave plants used for the production of mescals in west-central Mexico. While traditional non-industrial growers in southern Jalisco cultivate up to 20 varieties of agave, the only variety that can be cultivated to produce Tequila legally recognized by the Mexican government is Agave tequilana Weber. var. azul, Blue Agave (NOM-006-SCFI-2012; Valenzuela 2011; Colunga-GarcíaMarín & Villarreal 2007).
Trends in Cultivation and Biodiversity Concerns
Because of the industry's efforts to meet growing demand, mono-crop plantations are replacing small traditional farmers with increasing speed. In 1950, nearly 50% of total Tequila produced was made from Blue Agave grown in mono-crop plantations while the rest was produced by farmers in river canyons using agaves from different species and varieties grown in milpa plots or collected from wild populations (Zizumbo-Villarreal et al. 2013). When Tequila acquired international protection under the 1978 Appellation of Origin the name “Tequila” became restricted to agave spirits (mescal) which were made with Agave tequilana Weber var. azul in 5 Mexican states: Nayarit, Jalisco, Michoacan, Tamaulipas & Guanajuanto (NOM-006-SCFI-2012; Valensuela Zapata & Nabhan 2003). The industry then pressured the government into supporting growth of Blue Agave by financing small producers(Zizumbo-Villarreal et al. 2013).
This led to a raw material surge that resulted in a market crash which made growing agave unappealing to many small growers who then abandoned cultivating the crop. This boom and bust cycle plays out every 8-10 years alongside the plant’s life cycle(Valensuela Zapata & Nabhan 2003). During short falls the industry has often resorted to using other species of agave including wild populations which has resulted in some wild populations being severely depleted by this activity, and an overall decrease in biodiversity (Valenzuela 2011).
To combat short falls the industry changed its strategy begining in 2000 (Zizumbo-Villarreal et al. 2013). It began renting land from small producers to increase crop density and intensify cultivation itself, applying agrochemicals (herbicides, fungicides, pesticides and fertilizers) and expanding cultivation to areas outside its optimum climate, topography and soil range (Valenzuela 2011). This has resulted in the displacement of traditional food crops and Agave landraces in the designated Appellation of Origin zone for Tequila as well as soil erosion and soil, air and water pollution (Zizumbo-Villarreal et al. 2013; Valensuela Zapata & Nabhan 2003).
Traditional, non-industrial farmers tend to maintain high levels of agro-biodiversity which is helpful to biodiversity conservation. In Mexico’s central western region near the south of the state Jalisco (where mescal originated) multiple landraces of Agave angustifolia Haw. are still cultivated for mescal production (Vargas-Ponce et al. 2009). Traditional cultivation practices, which include in situ management of wild populations, are being replaced as commercial Blue Agave monoculture plantations expand (Vargas-Ponce et al. 2009). Loss of landraces threatens biodiversity because A. angustifolia's traditional landraces have genetic diversity similar to wild populations (Valenzuela 2011; Vargas-Ponce et al. 2009).
Most botanists agree that Blue Agave is among the most economically important species of the Rigidae section of the genus Agave. According to Gentry’s 1982 comparative analysis of floral morphology, the Blue Agave is derived from one species of highly adaptable Agave called Agave angustofolia (Valenzuela Zapata & Nabhan 2003). It has been acknowledged by many botanists, including Gentry, that the separation of Blue Agave as its own species is nominal (Gentry 1982). However, he and others have been reluctant to synonymize it with the wild species A. angustifolia because the tradition of maintaining separation is important to the Tequila industry (Valensuela Zapata & Nabhan 2003). The Tequila industry relies on the species classification of A. tequilana to provide commercial distinction between Tequila and other mezcals (Valensuela Zapata & Nabhan 2003).
The low genetic diversity of this nominal species has made it especially vulnerable to disease, climate shifts and pests (including the bacterium Erwina carotovora and the fungus Fusarium oxysporum) which has led to years when entire fields have been lost to blights (Simpson et al. 2011; Dalton 2005; Valensuela Zapata & Nabhan 2003). Recent research demonstrates there may be more genetic diversity within the Blue Agave species than first thought and that it could be exploited to promote stability and health of the crop, however this process would likely require that the zone of Appellation of Origin be expanded (Simpson et al. 2011; Vargas-Ponce et al. 2009; Colunnga-GarcíaMarín et al. 2007).
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