146 research outputs found
Quantifying soil carbon stocks and greenhouse gas fluxes in the sugarcane agrosystem: point of view
Strategies to mitigate climate change through the use of biofuels (such as ethanol) are associated not only to the increase in the amount of C stored in soils but also to the reduction of GHG emissions to the atmosphere.This report mainly aimed to propose appropriate methodologies for the determinations of soil organic carbon stocks and greenhouse gas fluxes in agricultural phase of the sugarcane production. Therefore, the text is a piece of contribution that may help to obtain data not only on soil carbon stocks but also on greenhouse gas emissions in order to provide an accurate life cycle assessment for the ethanol. Given that the greenhouse gas value is the primary measure of biofuel product quality, biorefiners that can show a higher offset of their product will have an advantage in the market place
Direct and indirect effects of soil fauna, fungi and plants on greenhouse gas fluxes
Soils harbour diverse soil fauna and a wide range of soil microorganisms. These fauna and microorganisms directly contribute to soil greenhouse gas (GHG) fluxes via their respiratory and metabolic activities and indirectly by changing the physical, chemical and biological properties of soils through bioturbation, fragmentation and redistribution of plant residues, defecation, soil aggregate formation, herbivory, and grazing on microorganisms and fungi. Based on recent results, the methods and results found in relation to fauna as well as from fungi and plants are presented. The approaches are outlined, and the significance of these hitherto ignored fluxes is discussed
Biochar: pyrogenic carbon for agricultural use: a critical review.
O biocarvão (biomassa carbonizada para uso agrícola) tem sido usado como condicionador do solo em todo o mundo, e essa tecnologia é de especial interesse para o Brasil, uma vez que tanto a ?inspiração?, que veio das Terras Pretas de Índios da Amazônia, como o fato de o Brasil ser o maior produtor mundial de carvão vegetal, com a geração de importante quantidade de resíduos na forma de finos de carvão e diversas biomassas residuais, principalmente da agroindústria, como bagaço de cana, resíduos das indústrias de madeira, papel e celulose, biocombustíveis, lodo de esgoto etc. Na última década, diversos estudos com biocarvão têm sido realizados e atualmente uma vasta literatura e excelentes revisões estão disponíveis. Objetivou-se aqui não fazer uma revisão bibliográfica exaustiva, mas sim uma revisão crítica para apontar alguns destaques na pesquisa sobre biochar. Para isso, foram selecionados alguns temaschave considerados críticos e relevantes e fez-se um ?condensado? da literatura pertinente, mais para orientar as pesquisas e tendências do que um mero olhar para o passad
Impacts of land use change to short rotation forestry for bioenergy on soil greenhouse gas emissions and soil carbon
Short Rotation Forestry (SRF) for bioenergy could be used to meet biomass
requirements and contribute to achieving renewable energy targets. As an important
source of biomass it is important to gain an understanding of the implications of
large-scale application of SRF on the soil-atmosphere greenhouse gas (GHG)
exchange. This study examined the effects of land use change (LUC) from grassland
to SRF on soil fluxes of methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2),
and the important drivers in action.
Examining soils from a range of sites across the UK, CO2 emission potentials were
reduced under SRF with differences between coniferous and broadleaved transitions;
these changes were found to be related to changes in soil pH and microbial biomass.
However, there were limited effects of SRF tree species type on CH4 and N2O fluxes.
A detailed study at an experimental SRF site over 16 months demonstrated a
reduction in CH4 and net CO2 emissions from soils under SRF and revealed intriguing
temporal dynamics of N2O under Sitka spruce and common alder. A significant
proportion of the variation in soil N2O fluxes was attributed to differences between
tree species, water table depth, spatial effects, and their interactions. The effects of
microtopography (ridges, troughs, flats), and its interactions with water table depth
on soil GHG fluxes under different tree species was tested using mesocosm cores
collected in the field. Microtopography did not significantly affect soil GHG fluxes
but trends suggested that considering this spatial factor in sampling regimes could
be important. N2O fluxes from Sitka spruce soils did not respond to water table depth
manipulation in the laboratory suggesting that they may also be determined by tree-driven
nitrogen (N) availability, with other research showing N deposition to be
higher in coniferous plantations. An N addition experiment lead to increased N2O
emissions with greatest relative response in the Sitka spruce soils.
Overall, LUC from rough grassland to SRF resulted in a reduction in soil CH4
emissions, increased N2O emissions and a reduction or no change in net CO2
emissions. These changes in emissions were influenced both directly and indirectly
by tree species type with Sitka spruce having the greatest effect on N2O in particular,
thus highlighting the importance of considering soil N2O emissions in any life cycle
analysis or GHG budgets of LUC to SRF for bioenergy. This research can help inform
decisions around SRF tree species selection in future large-scale bioenergy planting
- …