Global Change Biology Bioenergy最新文献

A field experiment was conducted in northeast China to examine the response of nitrogen cycling enzymes, that is, protease, N-acetyl-β-D-glucosaminidase (NAG), amidase, urease, and peptidase, as well soil organic nitrogen (SON) fractions and their relationships to RT (no maize residue application), NT (no tillage with maize residues placed on the surface), TT (plow maize residues into the soil at 0–35 cm depth in the first year, 0–20 cm in the second year, and 0–15 cm in the third year), and PT (plow maize residues into soil at 0–35 cm depth). The results have shown that NT significantly enhanced the activities of protease and NAG at 0–10 cm soil depth in comparison with other treatments. NT and TT significantly enhanced the activities of protease compared to RT and PT at 10–20 cm soil depth. TT significantly enhanced the activities of NAG in comparison with RT at 10–20 cm soil depth. TT and PT significantly enhanced the activities of NAG and peptidase compared to RT and NT at 20–35 cm soil depth. PT significantly increased the activities of protease in comparison with RT at 20–35 cm soil depth. NT, TT, and PT significantly enhanced the activities of peptidase compared to RT at 10–20 cm soil depth. NT significantly increased the concentration of hydrolyzable $��{\mathrm{NH}}_4^{+}�-�N�$ in comparison with other treatments at 0–10 cm soil depth. PT significantly enhanced the concentration of hydrolyzable $��{\mathrm{NH}}_4^{+}�-�N�$ and amino acid N compared to other treatments at 20–35 cm soil depth. Redundancy analysis showed that protease played a crucial role in the cycling of SON under RT and NT, whereas peptidase and NAG played a significant role in the cycling of SON under TT and PT, respectively. This study provided a comprehensive understanding of crop residue return methods for regulating soil N cycling.

Biochar is promoted as a means of improving soil fertility. Yet, few experiments have investigated its potential to improve nitrogen (N) use efficiency for high-yielding maize production in the U.S. Midwest. We tested the hypothesis that biochar application increases inorganic soil N availability during maize growth, leading to higher grain yields and N recovery efficiency while reducing the risk of N leaching following harvest. Four N fertilizer rates (0, 90, 179, and 269 kg ha⁻¹ as urea ammonium nitrate [UAN] solution) were applied with or without biochar (10 Mg ha⁻¹) before planting in a two-year field study. Inorganic soil N concentration was measured during the growing season (0–15 cm), and deep soil cores were obtained following harvest (0–90 cm). Results show that biochar did not affect maize yield, crop N uptake, or N recovery efficiency (by the difference method) across N rates, and there was no biochar by N rate interaction. While biochar lowered soil inorganic N concentrations on several sampling dates, this did not translate into seasonal differences in cumulative soil N availability, although grain yields in the unfertilized control were ~10% lower with biochar, suggesting net N immobilization. Biochar partially reduced the risk of N leaching following harvest by decreasing soil N concentrations at 30–60 cm, but mean concentrations for 0–90 cm were not different. Compared to previous work highlighting the benefits of biochar in arid climates with low soil fertility, we found no evidence of increased crop yield, NRE, or reduced risk of N leaching on Mollisols in a temperate climate.

Green hydrogen, produced during microalgal photosynthesis, is regarded as one of the most promising sustainable energy sources. It utilizes sunlight and water, which are essentially unlimited, and its combustion results in only water as a waste product. In microalgal hydrogen energy production systems, the sensitivity of hydrogenase to O₂ poses a significant challenge, limiting sustained photosynthetic H₂ production in microalgae. Additionally, efficient photosynthetic H₂ production in anaerobic microalgal cells is hindered by impaired electron source (photosystem II) and electron loss through the Calvin-Benson cycle, cyclic electron transfer around photosystem I, and O₂ photoreduction, which are identified as the other key challenges. Over the past eight decades, considerable progress has been made in addressing these challenges and regulating electron transfer to achieve sustainable and efficient photosynthetic H₂ production in microalgae. In this review, we discuss a range of regulatory methods for achieving sustainable and efficient photosynthetic H₂ production in microalgae. Emphasizing the significant progress made over the past eight decades, we also address current challenges and propose potential future solutions.

Manure is a leading source of methane (CH₄), nitrous oxide (N₂O), and ammonia (NH₃) emissions, and alternative manure management practices can help society meet climate goals and mitigate air pollution. Recent studies show that biochar-composting can substantially reduce emissions from manure. However, most studies test only one type of biochar applied at a single application rate, leading to high variation in emission reductions between studies. Here, we measured greenhouse gas and NH₃ emissions during biochar-composting of dairy manure with biochar applied at 5% or 20%, by mass, and made from walnut shells, almond shells, or almond clippings. We found little difference in emissions between biochar type. However, we found that the 20% application rates increased CH₄ emissions and decreased N₂O and NH₃ emissions, resulting in a net reduction in global warming potential (GWP). We attribute this result to biochar increasing the formation of compost aggregates, which likely acted as anaerobic reactors for methanogenesis and complete denitrification. Biochar may have further fueled CH₄ production and N₂O consumption by acting as an electron shuttle within aggregates. We recommend lower application rates, as we found that the 5% treatments in our study led to a similar reduction in GWP without increasing CH₄ emissions.

The application of biochar and nitrogen fertilizer can increase rice yield, soil organic carbon (SOC) storage and reduce greenhouse gas (GHG) emissions. However, few studies have systematically evaluated the carbon footprint (CF) and net ecosystem economic benefits (NEEB) of paddy ecosystems under long-term application of biochar and nitrogen fertilizer. Here, the life cycle assessment method was used to quantify the CF and NEEB of paddy fields under different biochar and nitrogen fertilizer application rates in 7 years. Three biochar rates of 0 (B0), 4.5 (B1) and 13.5 t ha⁻¹ year⁻¹ (B2) and two nitrogen fertilizer rates of 0 (N0) and 300 kg ha⁻¹ year⁻¹ (N) were set. The results showed that B2 significantly increased methane (CH₄) emission by 38%, decreased nitrous oxide (N₂O) emission by 29%, and significantly increased global warming potential by 27% compared with B0. Besides that, biochar application significantly increased ΔC_SOC by 87%–173% and reduced CF by 1.6–1.8 Mg CO₂ eq ha⁻¹. Among them, CH₄ and N₂O emissions contributed 46%–95% of total GHG emissions, and the production and transportation of nitrogen fertilizer and biochar contributed 17%–52% of total GHG emissions. Nitrogen fertilizer application can significantly increase rice yield by 85% compared to the N0, which could bring the largest NEEB. Biochar application had a negative influence on the NEEB regardless of N application. This might be attributable to the fact that the economic gains from increased rice production and SOC caused by biochar cannot outweigh the high cost of biochar. These results suggest that the biochar application can significantly improve the SOC sequestration and reduce the CF, but also had negative effect on NEEB in paddy filed.

Miscanthus is a genus of perennial grasses native to East Asia that shows promise as a biofuel energy source. Breeding efforts for increasing biofuel capability in this genus have focused on two species, namely M. sinensis (Msi) and M. sacchariflorus (Msa). For these efforts to succeed, it is critical that both Msi and Msa, as well as their interspecific crosses, can be grown at a wide range of latitudes. Therefore, the purpose of this study was to investigate how well existing data from Msi and Msa trials grown at locations throughout the northern hemisphere can train state-of-the-art genomic selection (GS) models to predict genomic estimated breeding values (GEBVs) of dry yield for untested Msi and Msa accessions in untested environments. We found that accounting for genotype by environment interaction in the GS model did not notably improve predictive ability. Additionally, we observed that locations at lower latitudes showed higher predictive ability relative to locations at higher latitudes. These results suggest that it is crucial to increase the number of trial locations at higher latitude locations to investigate the source of this correlation. This will make it possible to train GS models using data from environments that are similar to growing conditions at the locations targeted by Msi and Msa breeders. Such an increase of trial locations in target environments could pave the way toward advancing breeding efforts for overwintering ability in Msi and Msa, and ultimately support the potential of Miscanthus as a biofuel crop.

The Renewable Energy Directive (RED II) by the European Union (EU) provides an updated framework for the use of renewable energy in the EU transport sector until 2030, and bans the use of biofuels with a high risk of causing indirect land-use change in high carbon stock areas (high ILUC-risk criteria). The only biofuel feedstock affected by this criterion is palm oil. We employ the computable general equilibrium (CGE) model DART-BIO for a scenario-based policy analysis and evaluate a phase-out of palm oil-based biodiesel, and an additional phase-out of soy oil-based biodiesel in the EU. Our results show that the palm phase-out has only a relatively small impact on global palm fruit production and total crop land use in tropical and subtropical regions, while the soy phase-out leads to a comparable stronger decrease in global soy production, and a reduction in total cropland use in soy-producing regions. Both policies lead to increased oilseed production in the EU. Therefore, farmer in Malaysia and Indonesia face a significantly reduced income. While European farmers profit the most, EU firms and households are confronted with higher expenditures. Finally, this study indicates that unilateral demand-side regulations for a single good in a single sector is not sufficient for effective environmental protection. Enhanced binding sustainability criteria and certification schemes for the use of all vegetable oils in every sector and industry as well as improved protection schemes for sensible forest areas are necessary.

Perennial bioenergy crops are a key tool in decarbonizing global energy systems, but to ensure the efficient use of land resources, it is essential that yields and crop longevity are maximized. Remedial shallow surface tillage is being explored in commercial Miscanthus plantations as an approach to reinvigorate older crops and to rectify poor establishment, improving yields. There are posited links, however, between tillage and losses in soil carbon (C) via increased ecosystem C fluxes to the atmosphere. As Miscanthus is utilized as an energy crop, changes in field C fluxes need to be assessed as part of the C balance of the crop. Here, for the first time, we quantify the C impacts of remedial tillage at a mature commercial Miscanthus plantation in Lincolnshire, United Kingdom. Net ecosystem C production based on eddy covariance flux observations and exported yield totalled 12.16 Mg C ha⁻¹ over the 4.6 year period after tillage, showing the site functioned as a net sink for atmospheric carbon dioxide (CO₂). There was no indication of negative tillage induced impacts on soil C stocks, with no difference 3 years post tillage in the surface (0–30 cm) or deep (0–70 cm) soil C stocks between the tilled Miscanthus field and an adjacent paired untilled Miscanthus field. Comparison to historic samples showed surface soil C stocks increased by 11.16 ± 3.91 Mg C ha⁻¹ between pre (October 2011) and post tillage sampling (November 2016). Within the period of the study, however, the tillage did not result in the increased yields necessary to “pay back” the tillage induced yield loss. Rather the crop was effectively re-established, with progressive yield increases over the study period, mirroring expectations of newly planted sites. The overall impacts of remedial tillage will depend therefore, on the longer-term impacts on crop longevity and yields.

To combat climate change, carbon dioxide must be prevented from entering the atmosphere or even removed from it. Biochar is one potential practice to sequester carbon, but its climate change mitigation potential depends on a multitude of parameters. Differentiating areas of low and high climate change mitigation through biochar addition is key to maximize its potential and effectively use the available feedstock for its production. This study models the realistic application of 1 metric tonne (t) per hectare (ha) of forest harvest residue derived biochar over the climatically and pedologically diverse agricultural area of British Columbia, Canada, and provides a framework and assumptions for reproducibility in other parts of the world. The model accounts for the direct (input of organic carbon) and indirect (enhanced plant biomass) effects of biochar on soil organic carbon stock, its impact on nitrous oxide emissions from soils, and the avoided emissions from the reduced lime requirement due to biochar's alkalinization potential. Impacts are modelled over 20-year time horizon to account for the duration and magnitude variation over time of biochar effect on plant biomass and nitrous oxide emissions from soil and conform to the IPCC GWP 20-year time horizon reporting. The results show that a single application of 1 t of biochar per ha⁻¹ can mitigate between 3 and 5 t CO₂e ha⁻¹ over a 20-year time frame. Applied to the 746,000 ha of agricultural land of British Columbia this translate to the mitigation of a total of 2.5 million metric tonnes (Mt) CO₂e over a 20-year time frame. Further, the results identify agricultural areas in the Lower Mainland region (the southwestern corner of British Columbia) as the area maximizing climate change mitigation potential through biochar addition due to a combination of relative high temperature, high precipitation, and crops with high nitrogen requirement.

Harvested wood products (HWP) may contribute to climate change mitigation by storing carbon and by replacing energy-intensive materials and fossil energy, reducing greenhouse gas (GHG) emissions. However, when assessing improved HWP utilisations, interactions between wood use pathways, the carbon stock dynamics, and the resulting effect on the GHG balance are still not well-understood. This research aims to assess the carbon sequestration effects of alternative wood product utilisations in four European Union (EU) countries. We conducted a material flow analysis of wood uses in France, Finland, Germany, and Spain for 2017 taking into account national production, imports, and exports. Then, we quantified the future dynamics of carbon stock in the HWP through time, assuming the same as in 2017 input and ignoring the forest sink. We then ran six alternative scenarios: two energy-focused (Energy, Energy+), two material-focused (Cascading, Material), one with extended half-life of the wood products (HL) and one as business as usual. For the simulation period (2020–2050), the material scenario leads to the highest mitigation benefits with a cumulative HWP net CO₂ removals of −502 Mt CO₂ for Germany, −290 Mt CO₂ for France, −118 Mt CO₂ for Spain, and −116 Mt CO₂ for Finland over the 30 years. The Energy+ scenario with an increase in wood usage for bioenergy generates a loss of the HWP pool of 351, 80, 77, and 6 Mt CO₂ for the same countries, not accounting for energy substitution effects. Overall, our results suggest that the HWP carbon stock can be increased in the short-medium term by prioritizing the use of wood for material purposes, while maintaining constant harvest. The HWP mitigation potential differed greatly according to national wood industry characteristics. Hence, tailoring the HWP mitigation strategies to the specific characteristics of the national wood chain would enhance the HWP climate benefits.