• Authors:
    • Newman, J. A.
    • Haerri, S. A.
    • Emiljanowicz, L.
    • Ryan, G. D.
  • Source: Ecological Entomology
  • Volume: 39
  • Issue: 3
  • Year: 2014
  • Summary: 1. Elevated CO2 can alter plant physiology and morphology, and these changes are expected to impact diet quality for insect herbivores. While the plastic responses of insect herbivores have been well studied, less is known about the propensity of insects to adapt to such changes. Genetic variation in insect responses to elevated CO2 and genetic interactions between insects and their host plants may exist and provide the necessary raw material for adaptation. 2. We used clonal lines of Rhopalosiphum padi (L.) aphids to examine genotype-specific responses to elevated CO2. We used the host plant Schedonorus arundinaceus (tall fescue; Schreb), which is capable of asexual reproduction, to investigate host plant genotype-specific effects and possible host plant-by-insect genotype interactions. The abundance and density of three R. padi genotypes on three tall fescue genotypes under three concentrations of CO2 (ambient, 700, and 1000ppm) in a controlled greenhouse environment were examined. 3. Aphid abundance decreased in the 700ppm CO2 concentration, but increased in the 1000ppm concentration relative to ambient. The effect of CO2 on aphid density was dependent on host plant genotype; the density of aphids in high CO2 decreased for two plant genotypes but was unchanged in one. No interaction between aphid genotype and elevated CO2 was found, nor did we find significant genotype-by-genotype interactions. 4. This study suggests that the density of R. padi aphids feeding on tall fescue may decrease under elevated CO2 for some plant genotypes. The likely impact of genotype-specific responses on future changes in the genetic structure of plant and insect populations is discussed.
  • Authors:
    • Jin, V. L.
    • Mitchell, R. B.
    • Follett, R. F.
    • Varvel, G. E.
    • Vogel, K. P.
    • Schmer, M. R.
  • Source: PLOS ONE
  • Volume: 9
  • Issue: 3
  • Year: 2014
  • Summary: Low-carbon biofuel sources are being developed and evaluated in the United States and Europe to partially offset petroleum transport fuels. Current and potential biofuel production systems were evaluated from a long-term continuous no-tillage corn (Zea mays L.) and switchgrass (Panicum virgatum L.) field trial under differing harvest strategies and nitrogen (N) fertilizer intensities to determine overall environmental sustainability. Corn and switchgrass grown for bioenergy resulted in near-term net greenhouse gas (GHG) reductions of -29 to -396 grams of CO2 equivalent emissions per megajoule of ethanol per year as a result of direct soil carbon sequestration and from the adoption of integrated biofuel conversion pathways. Management practices in switchgrass and corn resulted in large variation in petroleum offset potential. Switchgrass, using best management practices produced 3919 +/- 117 liters of ethanol per hectare and had 74 +/- 2.2 gigajoules of petroleum offsets per hectare which was similar to intensified corn systems (grain and 50% residue harvest under optimal N rates). Co-locating and integrating cellulosic biorefineries with existing dry mill corn grain ethanol facilities improved net energy yields (GJ ha(-1)) of corn grain ethanol by >70%. A multi-feedstock, landscape approach coupled with an integrated biorefinery would be a viable option to meet growing renewable transportation fuel demands while improving the energy efficiency of first generation biofuels.
  • Authors:
    • Don, A.
    • Poeplau, C.
  • Source: GCB Bioenergy
  • Volume: 6
  • Issue: 4
  • Year: 2014
  • Summary: Bioenergy has to meet increasing sustainability criteria in the EU putting conventional bioenergy crops under pressure. Alternatively, perennial bioenergy crops, such as Miscanthus, show higher greenhouse gas savings with similarly high energy yields. In addition, Miscanthus plantations may sequester additional soil organic carbon (SOC) to mitigate climate change. As the land-use change in cropland to Miscanthus involves a C-3-C-4 vegetation change (VC), it is possible to determine the dynamic of Miscanthus-derived SOC (C-4 carbon) and of the old SOC (C-3 carbon) by the isotopic ratio of C-13 to C-12. We sampled six croplands and adjacent Miscanthus plantations exceeding the age of 10 years across Europe. We found a mean C-4 carbon sequestration rate of 0.78 +/- 0.19 Mg ha(-1) yr(-1), which increased with mean annual temperature. At three of six sites, we found a significant increase in C-3 carbon due to the application of organic fertilizers or difference in baseline SOC, which we define as non-VC-induced SOC changes. The Rothamsted Carbon Model was used to disentangle the decomposition of old C-3 carbon and the non-VC-induced C3 carbon changes. Subsequently, this method was applied to eight more sites from the literature, resulting in a climate-dependent VC-induced SOC sequestration rate (0.40 +/- 0.20 Mg ha(-1) yr(-1)), as a step toward a default SOC change function for Miscanthus plantations on former croplands in Europe. Furthermore, we conducted a SOC fractionation to assess qualitative SOC changes and the incorporation of C-4 carbon into the soil. Sixteen years after Miscanthus establishment, 68% of the particulate organic matter (POM) was Miscanthus-derived in 0-10 cm depth. POM was thus the fastest cycling SOC fraction with a C-4 carbon accumulation rate of 0.33 +/- 0.05 Mg ha(-1) yr(-1). Miscanthus-derived SOC also entered the NaOCl-resistant fraction, comprising 12% in 0-10 cm, which indicates that this fraction was not an inert SOC pool.
  • Authors:
    • Kludze, H.
    • McDonald,I.
    • Dadfar, H.
    • MacLean, H. L.
    • Dias, G.
    • Deen, B.
    • Sanscartier, D.
  • Source: GCB Bioenergy
  • Volume: 6
  • Issue: 4
  • Year: 2014
  • Summary: Replacement of fossil fuels with sustainably produced biomass crops for energy purposes has the potential to make progress in addressing climate change concerns, nonrenewable resource use, and energy security. The perennial grass Miscanthus is a dedicated energy crop candidate being field tested in Ontario, Canada, and elsewhere. Miscanthus could potentially be grown in areas of the province that differ substantially in terms of agricultural land class, environmental factors and current land use. These differences could significantly affect Miscanthus yields, input requirements, production practices, and the types of crops being displaced by Miscanthus establishment. This study assesses implications on life cycle greenhouse gas (GHG) emissions of these differences through evaluating five Miscanthus production scenarios within the Ontario context. Emissions associated with electricity generation with Miscanthus pellets in a hypothetically retrofitted coal generating station are examined. Indirect land use change impacts are not quantified but are discussed. The net life cycle emissions for Miscanthus production varied greatly among scenarios (-90-170 kg CO(2)eq per oven dry tonne of Miscanthus bales at the farm gate). In some cases, the carbon stock dynamics of the agricultural system offset the combined emissions of all other life cycle stages (i.e., production, harvest, transport, and processing of biomass). Yield and soil C of the displaced agricultural systems are key parameters affecting emissions. The systems with the highest potential to provide reductions in GHG emissions are those with high yields, or systems established on land with low soil carbon. All scenarios have substantially lower life cycle emissions (-20-190 g CO(2)eq kWh(-1)) compared with coal-generated electricity (1130 g CO(2)eq kWh(-1)). Policy development should consider the implication of land class, environmental factors, and current land use on Miscanthus production.
  • Authors:
    • Bjornsson,L.
    • Prade,T.
  • Source: Proceedings of the 9th International Conference on Life Cycle Assessment in the Agri-Food Sector
  • Year: 2014
  • Summary: In an analysis of climate effects, increased soil organic carbon will have a dual effect due to both increased soil fertility and carbon sequestration. Even so, soil carbon changes are neglected in many crop production LCAs. In the present study, the introduction of grass-clover crops in cereal-dominated crop production was evaluated. The grass-clover crops were used for biogas production, and the digested residue was recycled to the farm as biofertilizer. A shift from the cereal-dominated crop rotation to integrated production of food crops and one or two years of grass-clover crops used as biogas feedstock would result in avoided emissions of 2-3 t CO 2-eq. ha -1 a -1. Integrated food and energy crop production would in this case improve soil organic carbon content at the same time as resulting in considerably decreased greenhouse gas emissions from the cultivation system.
  • Authors:
    • Peter,C.
    • Fiore,A.
    • Nendel,C.
    • Xiloyannis,C.
  • Year: 2014
  • Summary: In this paper, we discuss different methods to calculate greenhouse gas field emissions from fertilization and soil carbon changes to be integrated into Carbon Footprint (CFP) of food and biomass products. At regional level, the simple Tier 1 approach proposed in the IPCC (2006a) AFOLU guidelines is often insufficient to account for emission variability which depends on soil type, climate or crop management. However, the extensive data collection required by Tier 2 and 3 approaches is usually considered too complex and time consuming to be practicable in Life Cycle Assessment. We present four case studies to compare Tier 1 with medium-effort Tier 2 and 3 methodologies. Relevant differences were found: for annual crops, a higher Tier approach seems more appropriate to calculate fertilizer-induced field emissions, while for perennial crops the impact on CFP was negligible. To calculate emissions related to soil carbon change higher Tiers are always more appropriate.
  • Authors:
    • Bernoux, M.
    • Bockel, L.
    • Tinlot, M.
    • Lipper, L.
    • Medeiros, K.
    • Benez, M. C.
    • Hissa, H.
    • Branca, G.
  • Source: Land Use Policy
  • Volume: 30
  • Issue: 1
  • Year: 2013
  • Summary: This paper presents the results of the EX-Ante Carbon-balance Tool (EX-ACT) application on two rural development projects in Brazil. The analysis provides an estimate of project impact on GHG emissions and C sequestration indicating net mitigation potential: results show that the Santa Catarina Rural Competitiveness Project has the potential to mitigate 12.2 Mt CO(2)e and the Rio de Janeiro Sustainable Rural Development Project 0.85 Mt CO(2)e. Both projects are successful at promoting activities aimed at reducing rural poverty and also contribute to climate change mitigation, demonstrating the potential importance of sustainable agriculture (improved cropland and grassland management, expansion of agro-forestry systems and protection of forested areas) in delivering environmental services. EX-ACT has also been used as a tool to guide project developers in refining components and activities to increase project environmental benefits. Cost-benefit analysis shows that while both projects generate environmental benefits associated with climate change mitigation, the Santa Catarina Rural Competitiveness Project has significantly higher potential due to the size of the project area and the nature of activities, thus a higher likelihood of potential co-financing from climate finance sources.
  • Authors:
    • Long, S. P.
    • Keogh, C.
    • Davis, S. C.
    • Anderson-Teixeira, K. J.
    • Duval, B. D.
    • Parton, W. J.
    • DeLucia, E. H.
  • Source: PLoS ONE
  • Volume: 8
  • Issue: 8
  • Year: 2013
  • Summary: Bioenergy related land use change would likely alter biogeochemical cycles and global greenhouse gas budgets. Energy cane (Saccharum officinarum L.) is a sugarcane variety and an emerging biofuel feedstock for cellulosic bio-ethanol production. It has potential for high yields and can be grown on marginal land, which minimizes competition with grain and vegetable production. The DayCent biogeochemical model was parameterized to infer potential yields of energy cane and how changing land from grazed pasture to energy cane would affect greenhouse gas (CO2, CH4 and N2O) fluxes and soil C pools. The model was used to simulate energy cane production on two soil types in central Florida, nutrient poor Spodosols and organic Histosols. Energy cane was productive on both soil types (yielding 46-76 Mg dry mass.ha(-1)). Yields were maintained through three annual cropping cycles on Histosols but declined with each harvest on Spodosols. Overall, converting pasture to energy cane created a sink for GHGs on Spodosols and reduced the size of the GHG source on Histosols. This change was driven on both soil types by eliminating CH4 emissions from cattle and by the large increase in C uptake by greater biomass production in energy cane relative to pasture. However, the change from pasture to energy cane caused Histosols to lose 4493 g CO2 eq.m(-2) over 15 years of energy cane production. Cultivation of energy cane on former pasture on Spodosol soils in the southeast US has the potential for high biomass yield and the mitigation of GHG emissions.
  • Authors:
    • Fisher, J.
  • Source: INTERNATIONAL SUGAR JOURNAL
  • Volume: 115
  • Issue: 1379
  • Year: 2013
  • Summary: The carbon footprint (GHG emissions) of sugar is of increasing interest to sugar users and consumers. This study considers the potential variability on a global basis of the carbon footprint of cane sugar, and investigates the key drivers affecting this variability. A mathematical model was built to represent the production of sugar from field to market. Key input values were replaced by ranges to reflect the variability and uncertainty associated with the diversity of sugar production scenarios worldwide. Monte Carlo simulation was carried out to simulate the effect of these variations on the model outputs, which were assessed against the Bonsucro method (with modifications and additions) for estimating GHG emissions. The carbon footprint of field-to-gate raw sugar ranged between 217 and 809 g CO2eq per kg sugar in 90% of simulations. The biggest drivers were the country of origin, agricultural methods, power production/export and process energy efficiency. Production of plantation white sugar and transport to a local market added another 100-150 g CO2eq/kg, split between transport and processing emissions. The carbon footprint of field-to-market factory-refined sugar ranged between 329 and 1121 g CO2eq/kg. The increase from raw sugar was mainly due to increased fossil fuel usage, and the biggest driver was process energy efficiency. The carbon footprint associated with shipping raw sugar from port, refining at a destination refinery, and transporting to market ranged between 465 and 660 g CO2eq/kg. The biggest driver was refinery energy efficiency. Finally, the carbon footprint of field-to-market destination-refined sugar ranged between 621 and 1459 g CO2eq/kg in 90% of simulations, of which the distance from factory to port was an additional significant driver. The potential variability in cane sugar carbon footprint has been shown to be large, depending on where and how it is produced. However, by focussing on areas such as irrigation, agricultural chemicals, cane yields, power generation and export, process energy efficiency and cane burning, it is realistic to achieve a negative carbon footprint for field-to-market refined sugar: a net emissions credit of 260 g CO2eq/kg was simulated, improving to 565 g CO2eq/kg with trash recovery and to 1470 g CO2eq/k9 with biomass gasification.
  • Authors:
    • Amiro, B. D.
    • Fraser, T. J.
  • Source: Canadian Journal of Soil Science
  • Volume: 93
  • Issue: 3
  • Year: 2013
  • Summary: Sequestering atmospheric carbon in agricultural soil is an attractive option for mitigation of rising atmospheric carbon dioxide concentrations. Perennial crops are more likely to gain carbon whereas annual crops are more likely to lose carbon. A pair of eddy covariance towers were set up near Winnipeg Manitoba, Canada, to measure the carbon dioxide flux over adjacent paired perennial grass hay fields with high soil organic carbon. A Treatment field was converted to annual cropping by spraying with herbicide, cutting and tilling. A Control field was cut, but allowed to re-grow. Differences in net ecosystem productivity between the fields were mainly caused by a loss of gross primary productivity in the Treatment field; ecosystem respiration was similar for both fields. When biomass removals and manure applications are included in the carbon budget, the Treatment field lost 149 g C M-2 whereas the Control field sequestered 96 g C m(-2), for a net difference of 245 g C M-2 over the June to December period (210 d). This suggests that perennial grass converted for annual cropping can lose more carbon than perennial grassland can sequester in a season.