Global Warming Potential Emissions Research Articles

Biochar as an Alternative Litter Additive to Mitigate Gaseous Emissions from Broiler Housing and Subsequent Storage

Broiler farming is a significant source of gaseous emissions. The aim of this study was to assess the effects of different litter additives on the emission of NH3, N2O, CO2, and CH4 during broiler housing and subsequent manure storage. The gaseous emissions from the housing facilities were evaluated during one fattening cycle in environmentally controlled rooms with three different additives applied to the litter material (10% w/w aluminum sulphate or biochar and 2.50 mg m−2 urease inhibitor), as well as a control. A storage experiment was conducted under laboratory conditions for 90 days to evaluate the influence of these three additives on gaseous losses. During broiler housing, the results indicated that NH3 emissions were reduced significantly (40–60%) by litter additives, while global warming potential (GWP) emissions were reduced significantly (31%) by Alum. The addition of Biochar (a 58% reduction) had the same significant effect as Alum (a 60% reduction) to mitigate these losses. The re-application of Urease (a 41% reduction) may be required to reach an equal or higher reduction. During storage, NH3 and GWP emissions were not significantly affected by the litter additives. During broiler housing and subsequent manure storage, NH3 emissions were reduced significantly (22–41%) by litter additives, whereas GWP emissions did not decrease significantly. Globally, it can be concluded that Biochar appears to be a good alternative to Alum due to its equal effectiveness in mitigating NH3 losses, without increasing the GWP potential in the housing and avoiding pollution swapping.

Mitigating methane emissions and global warming potential while increasing rice yield using biochar derived from leftover rice straw in a tropical paddy soil

The sustainable management of leftover rice straw through biochar production to mitigate CH4 emissions and enhance rice yield remains uncertain and undefined. Therefore, we evaluated the effects of using biochar derived from rice straw left on fields after harvest on greenhouse gas emissions, global warming potential (GWP), and rice yield in the paddy field. The experiment included three treatments: chemical fertilizer (CF), rice straw (RS, 10 t ha−1) + CF, and rice straw-derived biochar (BC, 3 t ha−1 based on the amount of product remaining after pyrolysis) + CF. Compared with CF, BC + CF significantly reduced cumulative CH4 and CO2 emissions, net GWP, and greenhouse gas emission intensity by 42.9%, 37.4%, 39.5%, and 67.8%, respectively. In contrast, RS + CF significantly increased cumulative CH4 emissions and net GWP by 119.3% and 13.8%, respectively. The reduced CH4 emissions were mainly caused by the addition of BC + CF, which did not increase the levels of dissolved organic carbon and microbial biomass carbon, consequently resulting in reduced archaeal abundance, unlike those observed in RS + CF. The BC + CF also enhanced soil total organic carbon content and rice grain yield. This study indicated that using biochar derived from leftover rice straw mitigates greenhouse gas emissions and improves rice productivity in tropical paddy soil.

Effects of Biochar Application Two Years Later on N2O and CH4 Emissions from RiceVegetable Rotation in a Tropical Region of China

The effects of biochar application on soil nitrous oxide （N2O） and methane （CH4） emissions in a typical rice-vegetable rotation system in Hainan after two years were investigated. The aim was to clarify the long-term effects of biochar on greenhouse gas emissions under this model， and it provided a theoretical basis for N2O and CH4 emission reduction in rice-vegetable rotation systems in tropical regions of China. Four treatments were set up in the field experiment， including no nitrogen fertilizer control （CK）； nitrogen， phosphorus， and potassium fertilizer （CON）； nitrogen， phosphorus， and potassium fertilizer combined with 20 t·hm-2 biochar （B1）； and nitrogen， phosphorus， and potassium fertilizer combined with 40 t·hm-2 biochar （B2）. The results showed that： ① compared with that in the CON treatment， the B1 and B2 treatments significantly reduced N2O emissions by 32% and 54% in the early rice season （P < 0.05， the same below）， but the B1 and B2 treatments significantly increased N2O emissions by 31% and 81% in the late rice season. The cumulative emissions of N2O in the pepper season were significantly higher than those in the early and late rice seasons， and the B1 treatment significantly reduced N2O emissions by 35%. There was no significant difference between the B2 and CON treatments. ② Compared with that in the CON treatment， B1 and B2 significantly reduced CH4 emissions by 63% and 65% in the early rice season， and the B2 treatment significantly increased CH4 emissions by 41% in the late rice season. There was no significant difference between the B1 and CON treatments. There was no significant difference in cumulative CH4 emissions between treatments in the pepper season. ③ The late rice season contributed to the main global warming potential （GWP） of the rice-vegetable rotation system， and CH4 emissions determined the magnitude of GWP and greenhouse gas emission intensity （GHGI）. After two years of biochar application， B1 reduced the GHGI of the whole rice-vegetable rotation system， and B2 increased the GHGI and reached a significant level. However， the B1 and B2 treatments significantly reduced GHGI in the early rice season and pepper season， and only the B2 treatment increased GHGI in the late rice season. ④ Compared with that in the CON treatment， the B1 and B2 treatments significantly increased the yield of early rice by 33% and 51%， and the B1 and B2 treatments significantly increased the yield of pepper season by 53% and 81%. In the late rice season， there was no significant difference in yield except for in the CK treatment without nitrogen fertilizer. The results showed that the magnitude of greenhouse gas emissions in the tropical rice-vegetable rotation system was mainly determined by CH4 emissions in the late rice season. After two years of biochar application， only low biochar combined with nitrogen fertilizer had a significant emission reduction effect， but high and low biochar combined with nitrogen fertilizer increased the yield of early rice and pepper crops continuously.

A modelled quantification of reduced nitrogen fertiliser requirement and associated trade-offs from inclusion of legumes and fallows in wheat-based crop sequences

ContextGlobally there is a need to increase crop production and maintain soil fertility while reducing environmental impact. Intensive wheat production is dependent on synthetic nitrogen (N) fertilisers which represent ∼38% of total on-farm greenhouse gas emissions in Australia and contribute to N pollution. There are four major sources of N available for crop production 1) N mineralised from native soil organic matter (SOM) 2) N derived from biological fixation by legume-associated rhizobial bacteria 3) synthetic N fertiliser 4) N-rich manures, composts, biosolids and other organic wastes. Farmers can emphasise use of these different sources through their management. ObjectivesIn this study we use crop simulation to predict the minimum amount of N fertiliser required for semi-arid wheat crops to achieve economic yield (EY – defined as 80% of water limited potential yield, PYw) when grown in long-term (1991–2020) sequences and at different rotational intensities with either; grain legumes (GL, source 2), legume winter cover crops (CC, source 2) and winter fallow (WF, source 1) compared to continuous wheat (CW, source 3). Results and conclusionsLegume and fallow phases at 25–67% intensity (e.g. one out of four to two out of three crops) reduced the long-term mean fertiliser N application required to achieve EY. For every % area increase of GL and CC, the mean N applied to achieve EY was reduced by 1.3 kg N kg ha-1 (0.43–1.9 N kg ha-1). For every % area increase of WF the mean N applied to achieve EY was reduced by 1.1 kg N kg ha-1 (0.4–1.6 N kg ha-1). Global warming potential emissions from soil (CO2 and N2O) increased compared to CW when legume intensity increased in high rainfall environments with high SOM but decreased at increasing intensity in low rainfall environments with low SOM. Food energy production (kJ ha-1yr-1) was reduced relative to CW by inclusion of CC and WF and to a lesser extent GL in sequences due to reduced total grain production over the study period. However, protein yield increased as GL intensity increased relative to CW. The most profitable sequences over a 30-year period were CW, or GL at different intensities depending on environment. ImplicationsDiversification of wheat-based cropping systems with legumes reduces N fertiliser requirement, but depending on farming system context this benefit can trade off against production, profitability and environmental outcomes. Evaluation and exploitation of appropriate farming system contexts to achieve mutually beneficial outcomes is required to allow farmers and policy makers to make informed decisions on how to increase food production whilst minimising environmental impacts.

THE SOCIAL COST OF CARBON EVALUATION BASED ON CARBON CAPTURE AND STORAGE TECHNOLOGIES FOR POWER GENERATION PLANTS

Power plants produce electricity using high amounts of fossil fuels such as coal. Using these fossil fuels releases very high emissions into the atmosphere. Carbon capture and storage (CCS) applications have been developed to reduce these emissions. Thus, by capturing 96% of the CO<sub>2</sub> formed from the burning of fuels in power plants, the global warming potentials emitted by conventional electricity generation can be reduced by up to 80%. The study investigated applications of CCS options to reduce emissions during electricity generation, CO<sub>2</sub> emissions, pre-combustion, post-combustion, and oxyfuel coupled global warming potentials. The reCiPe midpoint method has been taken into account for CO<sub>2</sub> emission. CCS options calculate the reduction in global warming potential. The study accepts that hard and brown coal is used as fuel in power plants that produce electricity. Finally, for the three cities with the highest electricity consumption in Turkey, the global warming potential emission in conventional electricity generation power plants burning brown coal is calculated as 43.4 kilotons for plants burning brown coal. It has been calculated as 6.2 kilotons in power plants using oxyfuel CCS and burning hard coal. Ten-year life for Istanbul, for hard coal burning and pre-combustion related discount rate of 1% and 3 $/ton social cost of carbon; The social cost of carbon is calculated as $102.8 million.

Effect of single basal application of controlled-release blended fertilizer on reactive nitrogen loss, carbon and nitrogen footprint during summer maize growth period

To elucidate the agronomic and environmental effects of single basal application of controlled-release blended fertilizer in summer maize, and optimize management measures of nitrogen fertilizer for grain production in North China Plain, we conducted a field experiment in Dezhou Modern Agricultural Science and Technology Park in Shandong Province. There were four treatments: CK (no N fertilizer), FFP (farmer's fertilizing practice, 240 kg N·hm-2), OPT (optimized nitrogen application, 210 kg N·hm-2), and CRBF (controlled-release blended fertilizer with single basal application, 210 kg N·hm-2). We compared maize yield and reactive nitrogen loss, and quantitatively evaluated the carbon and nitrogen footprints by using life cycle assessment method. The results showed that nitrogen application significantly increased summer maize yield. Compared with FFP, OPT and CRBF increased summer corn yield by 0.7% and 2.9%, respectively, decreased the total amount of ammonia volatilization, N2O emission, and nitrate leaching by 13.0% and 72.7%, 13.3% and 37.5%, 20.5% and 23.5% respectively. Compared with CK, nitrogen application significantly increased the global warming potential (GWP) of summer maize production. Compared with FFP, GWP and greenhouse gas emission intensity of OPT decreased by 3.8% and 4.2%, while the reduction of CRBF were 8.7% and 12.0%, respectively. Compared with CK, nitrogen application significantly increased the carbon and nitrogen footprint of summer maize production. The production and transportation of nitrogen fertilizer and soil greenhouse gas emission were the main contributing factors of the carbon footprint, with contribution rates of 54%-60% and 24%-31%, respectively. Nitrate leaching was the main contributing factor of nitrogen footprint, with contribution rate of 57%-94%. Compared with FFP, the carbon and nitrogen footprints of OPT and CRBF were reduced by 11.0% and 16.5%, 19.6% and 28.4%, respectively. Considering the yield, reactive nitrogen loss and carbon and nitrogen footprint, we recommended the single basal application of controlled-release blended fertilizer as an effective nitrogen fertilizer management measure to promote grain clean production in the North China Plain.

Effects of integrated nutrient management and urea deep placement on rice yield, nitrogen use efficiency, farm profits and greenhouse gas emissions in saline soils of Bangladesh

Soil salinity is one of the major yield-limiting factors in the coastal ecosystems of Bangladesh. An efficient fertilizer management practice and selection of appropriate crop cultivars could play a crucial role in improving yield and promoting low-carbon agriculture across saline soils. A two-year multi-location field experiment was conducted during the Boro (dry) season (December–April) to investigate the effects of fertilizer management and rice cultivar selection on rice yield, economic viability, and global warming potential (GWP) in coastal saline soils of Bangladesh. The study included seven fertilizer treatments with varying nitrogen rates and sources, as well as two rice cultivars (BRRI dhan67 and BRRI dhan88). The results showed that integrated nutrient management-2 (INM-2) significantly (p < 0.05) increased rice yield and nitrogen use efficiency compared to other treatments for both BRRI dhan67 and BRRI dhan88. Similarly, INM-2 gave a higher return on fertilizer investment and marginal benefit-cost ratio than other treatments in both locations and under both cultivars. BRRI dhan67 significantly (p < 0.05) increased rice yield relative to BRRI dhan88 by 21 % and 52 % at the BRRI farm and Kaliganj in Satkhira, respectively. The cost-dominant analysis excluded BRRI dhan88 and all fertilizer treatments, except urea deep placement (UDP) and INM-2, from consideration in both locations. Consequently, INM-2 and UDP proved to be economically viable in both locations, with INM showing a higher marginal rate of return than UDP in BRRI dhan67. In terms of environmental sustainability, UDP significantly (p < 0.05) reduced GWP and yield-scaled emissions of CH4 by 31 % and 38 % without causing yield loss compared to INM-2. Similarly, BRRI dhan67 significantly (p < 0.05) reduced GWP and yield-scaled emissions of CH4 by 5 and 22 % compared to BRRI dhan88. These findings suggest that selecting salt-tolerant rice cultivars and implementing appropriate fertilizer management practices can enhance economic profitability, ensure food security, and mitigate the adverse effects of climate change in coastal saline soils.

Optimizing sowing patterns in winter wheat can reduce N2O emissions and improve grain yield and NUE by enhancing N uptake.

Increasing nitrogen (N) input is essential to satisfy the rising global wheat demand, but this increases nitrous oxide (N2O) emissions, thereby exacerbating global climate change. Higher yields accompanied by reduced N2O emissions are essential to synergistically reduce greenhouse warming and ensure global food security. In this study, we conducted a trial using two sowing patterns (conventional drilling sowing [CD] and wide belt sowing [WB], with seedling belt widths of 2-3 and 8-10 cm, respectively) with four N rates (0, 168, 240, and 312kg ha-1, hereafter N0, N168, N240, and N312, respectively) during the 2019-2020 and 2020-2021 growing seasons. We investigated the impacts of growing season, sowing pattern, and N rate on N2O emissions, N2O emissions factors (EFs), global warming potential (GWP), yield-scaled N2O emissions, grain yield, N use efficiency (NUE), plant N uptake and soil inorganic N concentrations at jointing, anthesis, and maturity. The results showed that sowing pattern and N rate interactions influenced the N2O emissions markedly. Compared to CD, WB significantly reduced cumulative N2O emissions, N2O EFs, GWP, and yield-scaled N2O emissions for N168, N240, and N312, with the largest reduction seen at N312. Furthermore, WB markedly improved plant N uptake and reduced soil inorganic N compared to CD at each N rate. Correlation analyses indicated that WB mitigated the N2O emissions at various N rates mainly through efficient N uptake and reduced soil inorganic N. The highest grain yield occurred under a combination of WB and N312, under which the yield-scaled N2O emissions were equal to the local management (sowing with CD at N240). In conclusion, WB sowing could synergistically decrease N2O emissions and obtain high grain yields and NUEs, especially at higher N rates.

Mechanical and GWP assessment of concrete using Blast Furnace Slag, Silica Fume and recycled aggregate

Demolition waste and cement production is responsible for 36 % of total waste produced on earth and 8 % of the worlds CO2 emissions, respectively. Due to limited research on concrete mixes containing ternary cementitious mixes (Ground Granulated Blast-furnace Slag (GGBS) and Silica Fume (SF)) and demolition waste, the paper reviewed the mechanical properties of concrete, and structural performance of reinforced beams. Thereafter, life cycle analysis (LCA) was investigated to understand the true environmental impact, focusing on Global Warming Potential (GWP). Results show that recycled concrete aggregates (RCA) had no significant negative impact on the compressive strength, tensile strength, and modulus of rupture of concrete. The inclusion of GGBS and SF in mixes containing RCA eliminated any negative impact and for all mixes produced greater strengths in comparison to the control mix, due to the secondary reaction of Ca (OH)2 and pore refinement. The flexural behaviour of the concrete beams with 0 %, 25 %, 50 % and 100 % RCA, 25 % GGBS and 5 % SF is similar. LCA results showed that replacing NA with 25 %, 50 % or 100 % RCA has no significant impact on the GWP emissions. This is because of the similar emissions associated with manufacturing and processing of recycled and natural aggregates. However, replacing cement with 5 % SF and 25 % GGBS improves the GWP environmental response of concrete significantly. Additionally, natural aggregates have a higher GWP contribution than that of recycled concrete aggregates by almost 80 % since the process of NA required quarry operation and transportation while the RCA are produced on site from an existing building waste.

Delivering Sustainable Housing through Material Choice

Increasing importance is being placed on sustainability worldwide to limit climate change’s effects. In New Zealand, a sizeable increase in demand for housing is driving a residential construction boom, with new dwelling consents increasing yearly for the last decade. The New Zealand Government’s commitment to sustainability has become legislation through the Climate Change Response (Zero Carbon) Amendment Act 2019. Therefore, the next stage is how the construction industry can limit and reduce its carbon emissions through one of the strategies, namely material choice. This study was intended to examine the influence of various building materials on climate change and to identify how more sustainable home construction and design in New Zealand may contribute to the government’s 2050 emissions reduction targets. A life-cycle assessment (LCA) was used in this study to investigate the global warming potential (GWP) produced by five case study houses and various material options for building envelope components. The study focused on the environmental impact of materials with high usage in industry and potential new materials that have shown an ability to conform to the New Zealand Building Code standards. It was found that case study House 1 (with timber flooring founded on senton piles with concrete footings, a timber frame, plywood wall cladding, and metal roof cladding) and House 2 (with a concrete waffle slab, a light steel frame, masonry wall cladding, and metal roof cladding) had the lowest GWP emissions compared to the other case study houses, with 631.13 and 633.16 kg CO2eq/m2, respectively. However, it should be noted that all the case study houses were not similar in size and design. In addition, the study investigated the different building envelope material options for the foundation, wall cladding, framing, and roof cladding. The study found that some new materials or materials that are not common in New Zealand could be used as an option for the housing envelope by having lower carbon emissions, such as 3D-printed concrete blocks compared with brick and concrete masonry for wall cladding systems.

Propriety assessment model for life cycle operational global warming potential of apartment buildings in Korea using energy efficiency and energy effective area data

In response to global warming, researchers worldwide are actively investigating various techniques and institutional frameworks to reduce the emission of greenhouse gases. Despite numerous life cycle assessment (LCA) studies indicating that global warming effects due to lifetime energy consumption are the greatest in the building operation stage, the absence of a standard global warming potential (GWP) report based on building energy usage makes it difficult to examine realistic GWP reduction directions. In South Korea, energy data for numerous buildings were collected through the Building Energy Efficiency Certification (BEEC) for several years, with data from apartment buildings receiving the most attention. GWP emissions were evaluated using the data through Green Standard for Energy and Environmental Design LCA. Here, we developed a model for apartment buildings to assess mutual propriety for GWP emissions (E) and energy effective area ratio (RE) during building operation to support the reduction of GWP emissions caused by lifetime operational energy consumption resulting from planning and design. We collected apartment BEEC data and used them to calculate the energy effective area ratio and GWP emissions of each building, which were then classified by energy use and source. Linear regression analysis was performed between RE and E for each classification, and the derived regression equation was developed as a GWP assessment model for apartments. The applicability of the proposed model was examined through a case study, which confirmed that the model can be used to determine design directions for reducing GWP emissions for every energy in apartments.

Program for propriety analysis of global warming potential caused by the operational energy consumption of buildings in Korea

Various studies have reported that energy consumption in the operation stage in the life cycle of a building has the largest impact on global warming. However, suggesting appropriate practical directions for reducing global warming potential (GWP) is challenging owing to the absence of appropriate standards for GWP according to building energy consumption. In South Korea, environmental data of various buildings have been accumulated based on building life cycle assessment, conducted by adhering to the G-SEED standard for many years. This study aimed to develop a program that can support sustainable design by evaluating the appropriateness of GWP in the building operation stage in a simple manner and consequently suggest directions for efficiently reducing GWP passively or actively. To develop the program, first, GWP standard models were derived for each building’s energy use and source. Subsequently, a program, E2C, was built to assess the appropriateness of GWP emissions according to the energy effective area ratio from the building to be assessed, for each energy use and source, by employing the derived standard models. Finally, the applicability of the proposed program was examined through a case study and it was confirmed that design directions for securing the appropriateness of GWP could be suggested through E2C. Consequently, E2C has the potential to be used in the design stages of sustainable buildings.

Mitigating Ammonia and Greenhouse Gas Emissions from Stored Pig Slurry Using Chemical Additives and Biochars

Slurry storage is a significant source of NH3 and greenhouse gas (GHG) emissions. The aim of this laboratory study was to assess the effects of different chemical additives and biochars on the emissions of NH3, N2O, CO2, and CH4 during the short-term storage of pig slurry. The experiment was performed using Kilner jars filled with raw slurry as control and six treatment additives (5% w/w): acidified slurry, alkalinized slurry, neutralized slurry, agroforestry biochar, cardoon biochar, and elderberry biochar. The gas emissions were measured for 30 days, and the composition of the slurries was determined. During short-term storage, the results of this laboratory study indicated that the NH3 emissions were reduced by 58% by acidification and by 20% by the biochars (Agroforestry, Cardoon, and Elderberry treatments), while neutralization reduced this loss by only 12%. Nitrous oxide emissions were not reduced by the chemical additives (Acidified, Alkalinized, and Neutralized treatments), while this loss was increased by 12% by the biochars. Carbon dioxide, CH4, and global warming potential emissions were not affected by the chemical additives and biochars. Furthermore, the absence of differences between the biochars may be related to their similar composition. Regarding the influence of the studied additives on NH3 losses, it can be concluded that acidification was the best mitigation measure and the biochars were quite similar due to their composition. Furthermore, neutralization had the advantage of sanitizing the slurry, but only had a mild impact on NH3 preservation.

Building circularity as a measure of sustainability in the old and modern architecture: A case study of architecture development in the hot and dry climate

Nowadays, the construction industry has turned to the consumption of large amounts of natural resources in line with global population growth, which has led to the shortage of resources, and consequently increases in the construction debris; therefore, the present article has studied the positive and negative points of the architectural development process. The results have indicated that being compared to the former architecture; the development of architecture has reduced energy consumption by 78%. Hence, the scarcity of virgin resources and consequently the increase of environmental effects such as Global Warming Potential (GWP) have been measured based on the Life Cycle Assessment (LCA). It has been illustrated that the architecture trend has increased the environmental impact of new materials by 5 times the old ones in GWP. To optimize and increase resource productivity, a review of buildings by the principles of Circular Economy (CE) has shown that 10% of old house materials and 3% of new house materials could be returned to the chain based on the CE concept. Other than reducing the GWP emissions of the construction industry and the development of zero waste systems, this paper, by replacing conventional materials with biocompatible, has been able to increase the Building Circularity (BC) by 27% in the old house and 3% in the new one, which emphasizes a regenerative approach. As a result, with this solution, more integrity would be observed between the construction environment and nature, both in the development of past architecture and in the improvement of future architecture.

Systematic data-driven exploration of Austrian wastewater and sludge treatment - implications for phosphorus governance, costs and environment

Within the new policy framework shaped by the EU Green Deal and the Circular Economy Action Plans, the field of wastewater and sludge treatment in Europe is subject to high expectations and new challenges related to mitigation of greenhouse gas emissions, micropollutant removal and resource recovery. With respect to phosphorus recovery, several technologies and processes have been thoroughly investigated. Nevertheless, a systemic and detailed understanding of the existing infrastructure and of the related environmental and economic implications is missing. Such basis is essential to avoid unwanted consequences in designing new strategies, given the long lifespan of any infrastructural change. This study couples a newly collected and highly detailed database for all wastewater treatment plants in Austria bigger than 2000 population equivalent with a combination of analyses, namely Substance Flow Analysis with focus on nutrient and metal distribution in different environmental and anthropogenic compartments, Energy Flow Analysis, Life Cycle Assessment and cost estimation. The case study of Austria is of special interest, given its highly autonomous administration in federal states and its contrasting traits, ranging from flat metropolitan areas like Vienna to low-populated alpine areas. The significant impact of electricity demand of wastewater treatment on the overall Cumulative Energy Demand (CED) shows the importance of optimization measures. Further, the current system of wastewater and sludge disposal have a low efficiency in recovering nutrients and in directing pollutants as heavy metals into final sinks. Sludge composting with subsequent use in landscaping does not only show an unfavorable environmental balance, but it is the only relevant route leading to additional CED and Global Warming Potential emissions and to the highest transport volume. Altogether, the outcomes of this study provide a sound basis to further develop national strategies for resource recovery aimed to optimize trade-offs between different economic and environmental objectives.

Effects of combined applications of straw with industrial and agricultural wastes on greenhouse gases emissions, temperature sensitivity, and rice yield in a subtropical paddy field

The incorporation of post-harvest crop straw and application of industrial and agricultural wastes to paddy soils increase rice crop yields and soil fertility. However, the impacts of combined applications of straw and waste products on greenhouse gas (GHG) emissions and global warming potential (GWP) of paddy soils are unclear. Therefore, we conducted a field experiment in subtropical rice in China to test the effects of applications of straw, straw+biochar, straw+shell slag, straw+gypsum slag, straw+silicon, and straw+steel slag on rice yields, GWP, and greenhouse gas emission intensity (GHGI). The results showed that, compared to the control, cumulative emissions of carbon dioxide (CO2) from paddy soils were 15.2, 16.9, and 36.6 % lower following application of straw+steel slag, straw+silicon, and straw+gypsum, respectively, and cumulative emissions of methane (CH4) were 5.0 and 62.1 % lower following application of straw+steel slag and straw+gypsum, respectively. Meanwhile, relative to the addition of straw alone, application of straw+steel slag and straw+gypsum reduced GHG emissions largely due to reductions in CO2 emissions, further declining the GWP of CO2 and GHGI. In addition, temperature sensitivity (Q10) of CO2 emissions was highest following application of straw+silicon and lowest following application of straw+gypsum. There were no treatment effects on mean dissolved porewater concentrations of CO2, CH4, or nitrous oxide (N2O) and soil emissions of CO2 were negatively correlated with mean dissolved concentrations of CO2, CH4, and N2O. Rice yields were reduced following application of straw+gypsum and unaffected by the other treatments. Thus, relative to the addition of straw alone or control, we suggest the combined application of straw+steel slag may improve the sustainability of paddy rice production, because it reduces GWP, while maintaining yields.

A global meta-analysis of crop yield and agricultural greenhouse gas emissions under nitrogen fertilizer application

Nitrogen fertilization (NF) is one of the common practices to increase crop production worldwide over the past several decades. Nevertheless, unreasonable NF results in massive greenhouse gas (GHG) emissions, leading to climate change and global warming. Many studies have already reported the impact of NF on crop yield, global warming potential (GWP) and greenhouse gas intensity (GHGI), but the studies were limited to only some parameters. In this study, a total of 174 studies from 16 countries were collected and then a regression analysis was conducted to obtain the appropriate N fertilization rates that enhance crop yield while reducing GWP and GHGI. After that, a meta-analysis was performed to evaluate the effects of NF on crop yield, GHGI, GWP and GHG emissions and identify NF management strategies that benefit crop yield and maintain GWP. The results showed that the suitable N fertilization rate was 180, 150, 130 and 200 kg ha−1 for wheat, maize, rice and vegetables or industrial crops, respectively. Overall, NF resulted in positive effect size in crop yield (0.56) and negative effect size in GHGI (−0.14) compared to NNF. GWP showed positive effect size (0.37) due to an increase in N2O emissions (0.91) relative to NNF, which is higher than the increase of CH4 emissions (0.01) and CO2 emissions (0.22). It was recommended that split and banded application of urea or urea plus manure is employed for cereals (especially wheat) in the arid and semi-arid regions with medium-textured and neutral or alkaline soil.

Greenhouse gas emissions and C costs of N release associated with cover crop decomposition are plant specific and depend on soil moisture: A microcosm study.

Cover cropping is used to improve soil quality and increase N inputs in agricultural systems, but it also may enhance greenhouse gases (GHG) emissions. Here, a 47-d incubation study was conducted to track the decomposition process and evaluate GHG emissions and its drivers and to calculate the C costs of residue-derived N released following the addition of residues from cover crops (pigeon pea, cowpea, lablab bean, vetch, and black oat) and maize under two water-filled pore space (WFPS) levels (40 and 70%). For both WFPS levels, the increase in cumulative CO2 fluxes in plots that received residues is mainly related with the increment of potentially mineralizable C. Crop residues increased the global warming potential (GWP) under both WFPS levels, with CO2 emissions accounting for ≥98% of the GWP at 40% WFPS. At 70% WFPS, the GPW increment was driven by a notable increase in N2 O emissions. The contribution of CH4 in the GWP emissions was negligible for all the crop residues evaluated. Principal component analysis highlighted that the optimal conditions for production and release are specific for each GHG. The cleaner N source was cowpea at 40% WFPS, which produced only 17.7kg CO2 -eq kg-1 N mineralized, compared with vetch residues, which produced 233kg CO2 -eq kg-1 N mineralized. To integrate agronomic and climate change mitigation perspectives, we suggest considering the C costs of the residue-N released when choosing a cover crop.

The Eco-Efficiency of Castor Supply Chain: A Greek Case Study

Castor is a candidate crop that grows in marginal lands in the Mediterranean area. It can be grown by utilizing minimal resources to provide unique industrial chemicals or to serve as an energy crop. However, it can be also cultivated with intensive inputs providing higher yields. Whether a high input or a low input scheme is more sustainable depends on the economic and environmental impacts of each case. The objective of the present study, therefore, was to evaluate these impacts under the Mediterranean climate and farming conditions by examining two alternative scenarios: a castor crop grown on a low-inputs field vs. a crop grown in a high-inputs one. The environmental impacts were estimated by following a Life Cycle Assessment (LCA) methodology based on GHG emissions. Furthermore, a sensitivity analysis was performed by switching the functional unit from 1 Mg of castor oil to 1 hectare. The economic feasibility of the castor crop production was assessed by calculating the gross margin, which is referred to the difference between revenues and the variable costs due to the agricultural phases. In addition, the ratio between gross margin and GWP (Global Warming Potential) emissions was applied to calculate the economic performance (gross margin) per unit of environmental burden. Findings showed that the castor oil produced by high inputs resulted in a more sustainable scenario due to its higher yield than low-inputs ones. On the other hand, sensitivity analysis showed that the field management with low inputs showed GHG emissions that were 27% lower than those emitted from the field management with high inputs. Moreover, from an economic point of view, by switching the field management from low inputs to high ones, the Gross Margin increased by about 73%. Finally, the high-inputs scenario showed the best ratio between economic performance and GHG emitted into the atmosphere.

Production of concrete using reclaimed water from a ready-mix concrete batching plant: Life cycle assessment (LCA), mechanical and durability properties

This study investigates novel methods and more sustainable techniques that have been developed to minimize the environmental damage of concrete production. The use of reclaimed water and supplementary cementitious materials in concrete can be a solution to the problems of water scarcity and excessive CO2 emissions. In this context LCA, mechanical and durability properties of concrete containing silica fume as a supplementary cementitious material (SCM) and reclaimed water as an alternative source of fresh water are studied. First several properties of concrete such as consistency, compressive strength, electrical resistance, chloride ion penetration and water penetration under pressure were measured. Then, the LCA of concrete using LCA web tool was evaluated and the global warming potential (GWP) emission rates along with air pollutants such as lead, volatile organic compounds, CO, NOX, PM10 and SO2 were determined. The results show that adding a certain level of silica fume is desirable in terms of environmental issues, cost and mechanical and durability properties of concrete. In concrete containing 5, 8 and 11% of silica fume, GWP emissions decreased by 4.9, 8 and 11.2%, respectively. On the other hand, the production of lead, volatile organic compounds (VOCs), CO, NOX and PM10 decreased by 2–12%, while SO2 production increased by 4–10%. According to the obtained results, the manufacture of concrete with the mixing ratios presented in this research in a large-scale ready-mix concrete batching plant that produces 576 tonnes concrete per year (240,000 m3/year) will lead to a reduction of GWP about 3900–8700 tonnes CO2-eq per year.