Use of swine waste-derived biogas to enhance microalgae productivity.

The effects of swine wastewater-derived biogas on microalgae productivity were determined. Experiments were conducted in a closed photobioreactor containing digestate effluent as culturing media and biogas in the headspaceas source of CO2. Experiments were carried out under mixothrophic and autothrophic conditions. Results showed that autotrophic growth rate (0.6 d-1)was twofoldfaster than mixotrophic. Frequent reinjections of biogas containing up to 2,000 ppm of hydrogen sulfide was not inhibitory to microalgae growth. The rapid removal of H2S in the system suggests photobioreactors can be an interesting alternative to biogas purification. A model to estimate microalgae productivity based on the amount of available CO2, inorganic and organic carbon was developedand showed good data fit correlation (r²= 0.99).

Sugarcane Water Productivity Assessments in the São Paulo state, Brazil.

São Paulo state, Brazil, has been highlighted by the sugarcane crop expansion. The actual scenario of climate and land use changes, bring attention for the large-scale water productivity (WP) analyses. MODIS images were used together with gridded weather data for these analyses. A generalized sugarcane growing cycle inside a crop land mask, from September 2011 to October 2012, was considered in the main growing regions of the state. Actual evapotranspiration (ET) is quantified by the SAFER (Simple Algorithm for Evapotranspiration Retrieving) algorithm, the biomass production (BIO) by the RUE (Radiation Use Efficiency) Monteith?s model and WP is considered as the ratio of BIO to ET. During the four generalized sugarcane crop phases, the mean ET values ranged from 0.6 to 4.0 mm day-1; BIO rates were between 20 and 200 kg ha-1 day-1, resulting in WP ranging from 2.8 to 6.0 kg m-3. Soil moisture indicators are applied, indicating benefits from supplementary irrigation during the grand growth phase, wherever there is water availability for this practice. The quantification of the large-scale water variables may subsidize the rational water resources management under the sugarcane expansion and water scarcity scenarios.

Growth and survival of Sclerolobium paniculatum vogel and the relationship between rainfall and the increment in diameter at different planting spacings.

Sclerolobium paniculatum Vogel is a species that has good potential for reclamation of degraded soils. The aim of the investigation was to evaluate the growth and survival of the species and the influence of rainfall on growth in diameter as a function of different spacings (4 m x 2 m, 4 m x 3 m, and 4 m x 4 m). The results indicate that the temporal analysis (period from November 2007 to August 2013) detected significant differences (p ? 0.05) in height between the 4 m x 2 m and 4 m x 4 m spacings, while no significant difference in diameter was found between the 4 m x 2 m and 4 m x 3 m spacings. However, the statistical differences did not persist when the data was analyzed at seven and half years old. Regarding survival, a significant difference was observed only between the 4 m x 4 m spacing and the others, with superiority to the former. A strong correlation was found between rainfall and the increment in diameter of individuals in the broader spacings (R = 0.80 in the 4 m x 3 m spacing and R = 0.77 in the 4 m x 4 m spacing), while in the denser spacing the correlation was moderate (R = 0.56 in the 4 m x 2 m spacing). Since the spacings adopted did not influence tree growth by the end of the period, the choice will depend on other factors such as survival and costs of implementation and forestry management. Plantations in regions with larger rainfall amplitude may benefit the productivity of the species.