Mass and energy fluxes were measured over a field of Agave tequilana in Mexico using eddy covariance (EC) methodology. Data were gathered over 252 d, including the transition from wet to dry periods. Net ecosystem exchanges (FN,EC ) displayed a crassulacean acid metabolism (CAM) rhythm that alternated from CO2 sink at night to CO2 source during the day, and partitioned canopy fluxes (FA,EC ) showed a characteristic four-phase CO2 exchange pattern. Results were cross-validated against diel changes in titratable acidity, leaf-unfurling rates, energy exchange fluxes and reported biomass yields. Projected carbon balance (g C m(-2)  year(-1) , mean ± 95% confidence interval) indicated the site was a net sink of -333 ± 24, of which contributions from soil respiration were +692 ± 7, and FA,EC was -1025 ± 25. EC estimated biomass yield was 20.1 Mg (dry) ha(-1)  year(-1) . Average integrated daily FA,EC was -234 ± 5 mmol CO2  m(-2)  d(-1) and persisted almost unchanged after 70 d of drought conditions. Regression analyses were performed on the EC data to identify the best environmental predictors of FA . Results suggest that the carbon acquisition strategy of Agave offers productivity and drought resilience advantages over conventional semi-arid C3 and C4 bioenergy candidates.

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The rise in temperature is an important event during the composting of lignocellulosic materials and has to be controlled and regulated to improve the biodegradation. Phase I mushroom composts were incubated under environmentally controlled conditions. When the temperature was pre-set at 65°C and then later at around 80°C, the microbial respiration and the biodegradations were hardly affected. However residual activities due to thermoresistant bacteria were still measured after 68 h at a constant temperature of 80°C. Significant changes in nitrogen resources were observed: loss of nitrogen from microbial products, an increase in the proportion of nitrogen in non-hydrolysable and stable forms, and an increase in volatilisation of ammonia. These changes were mainly due to physico-chemical mechanisms associated with disturbances in the structure of the microbial community.

El agave azul es la materia prima para la producción de tequila a través de un proceso de destilación que genera alrededor de 400 mil toneladas anuales de bagazo, el cual, parcialmente, se transforma en composta. Las plantas de agave micropropagadas requieren un periodo de adaptación de alrededor de nueve meses en vivero o invernadero tipo casa sombra, para lo cual se cultivan en contenedor con un sustrato comercial. Para esta etapa, no existen aún parámetros morfológicos que sirvan como referencia para evaluar la calidad de las plantas para proceder a la plantación en campo. Por lo tanto, el objetivo del estudio fue evaluar algunas respuestas morfológicas de plántulas del agave azul (microporpagado) cultivado con diferentes sustratos orgánicos: un sustrato comercial (80% polvo de coco, 10% turba y 10% composta de bagazo de agave), polvo de coco, turba canadiense y cuatro mezclas de composta de bagazo de agave. Se estableció un diseño experimental completamente al azar con cuatro repeticiones, considerando cada planta como unidad experimental, en un invernadero tipo casa sombra, entre septiembre de 2007 y junio de 2008, en Tequila, Jalisco, México. Los resultados fueron evaluadosestadísticamentemedianteANVAycomparación de medias por DMS. La mezcla de sustrato con los mejores resultados fueron los tratamientos con la composta de bagazo al 50%, seguida por la composta al 30% y finalmente al 70%, complementadas con polvo de coco. Los valores máximos de las variables de estudio registradas fueron: diámetro de piña, 5.0 cm; diámetro del tallo, 3.8 cm; número de hojas, 15; longitud de hoja, 55.4 cm y anchura de hoja más larga, 4 cm, los cuales son medidas que podrían emplearse como estándares de calidad del agave antes de la plantación en campo.

No abstract