CO2e Ha-1 Research Articles

Soil greenhouse gas fluxes partially reduce the net gains in carbon sequestration in mangroves of the Brazilian Amazon

There is interest in assessing the potential climate mitigation benefit of coastal wetlands based on the balance between their greenhouse gas (GHG) emissions and carbon sequestration. Here we investigated soil GHG fluxes (CO2 and CH4) on mangroves of the Brazilian Amazon coast, and across common land use impacts including shrimp farms and a pasture. We found greater methane fluxes near the Amazon River mouth (1439 to 3312 μg C m−2 h−1), which on average are equivalent to 37% of mangrove C sequestration in the region. Soil CO2 fluxes were predominant in mangrove forests to the East of the Amazon Delta. Land use change shifted mangroves from C sinks (mean sequestration of 12.2 ± 1.4 Mg CO2e ha−1 yr-1) to net GHG sources (mean loss of 8.0 ± 3.3 Mg CO2e ha−1 yr−1). Our data suggests that mangrove forests in the Amazon can aid decreasing the net annual emissions in the Brazilian forest sector in 9.7 ± 0.8 Tg CO2e yr−1 through forest conservation and avoided deforestation.

Cover crops support the climate change mitigation potential of agroecosystems.

Cover crops have the potential to mitigate climate change by reducing negative impacts of agriculture on ecosystems. This study is first to quantify the net climate change mitigation impact of cover crops including land-use effects. A systematic literature and data review was conducted to identify major drivers for climate benefits and costs of cover crops in maize (Zea maize L.) production systems. The results indicate that cover crops lead to a net climate change mitigation impact (NCCMI) of 3.30 Mg CO2e ha-1 a-1. We created four scenarios with different impact weights of the drivers and all of them showing a positive NCCMI. Carbon land benefit, the carbon opportunity costs based on maize yield gains following cover crops, is the major contributor to the NCCMI (34.5% of all benefits). Carbon sequestration is the second largest contributor (33.8%). The climate costs of cover crops are mainly dominated by emissions from their seed production and foregone benefits due to land use for cover crops seeds. However, these two costs account for only 15.8% of the benefits. Extrapolating these results, planting cover crops before all maize acreage in the EU results in a climate change mitigation of 49.80 million Mg CO2e a-1, which is equivalent to 13.0% of the EU's agricultural emissions. This study highlights the importance of incorporating cover crops into sustainable cropping systems to minimize the agricultural impact to climate change.

Carbon footprint estimation for tillage operations

As a larger use of agricultural machinery, the measurement of carbon emission is highly important. Quantification of the carbon footprint is important for the identification of more sustainable and environmentally friendly practices. Information about input energy (fuel energy) used by some tillage techniques was collected and converted into carbon. In order to use low emission tillage operations, the equivalent carbon emission factors of each tillage technique were determined. The carbon equivalents for using traditional tillage system were the highest comparing with other tillage systems (158.63 kg CE ha-1 and 55.63 kg CO2e ha-1), while No-till system which give (5.8 kg CE ha-1 and 5.45 kg CO2e ha-1). Improved conservation technology and management equipment can all help minimize the carbon footprints of farm machinery.

Carbon cycle of native pasture-based beef cattle production systems in the Pantanal area of the Paraguayan Chaco

The objective of the present study was evaluate the carbon cycle in Paraguayan Pantanal area native grassland ecosystems by measuring pasture growth and simulating animal grazing. For this purpose, soil analyzes, annual productivity and forage quality were carried out in 4 agro ecological sites of a 20,000 ha located in Alto Paraguay Department (21º 1' 29.85”S and 58º 17' 38.55” W), from Dec 21, 2019 to Feb 12, 2020. In the selected location was installed an 8 m x 8 m exclusion cage with three treatments (4 m2 subplots), corresponding to cutting intervals (35, 70 and 105 CI days, respectively). The seasonal dry matter (DM) production and the pasture growth rate, adjusted stocking rate at three production levels (50, 70 and 75% breeding rate, respectively), carbon contained in organic matter (OM), root system and aerial biomass accumulated in ground were evaluated. The data were compared using Tukey test with a 5% probability. The emission of greenhouse gases (GG) per head and per ha was simulated and adjusted to breeding livestock to a total area of 6,600 ha and 5,000 grassland ha. The 35 days CI presented 32% higher productivity than 105 days CI in carbon sequestration. The best capture/emission balance per ha was observed in 35 days CI with the 50% breeding rate, producing 1,481 kg of CO2-e ha-1, intensifying and increasing the breeding rate to 75%, the balance decreases to 1,294 kg of CO2-e ha-1. In all cases, livestock in grassland has presented a positive balance when accounting for GG per unit area.

Assessment of Blue Carbon Stock of Coringa Mangroves: Climate Change Perspective

‘Blue carbon’ has recently seized the attention of the scientific communities as they are believed to provide the benefits of climate change mitigation given its high potential to store carbon under unfavourable conditions. Keeping in mind the importance of the carbon storage capacity of mangroves, the present study has been carried out to determine the sedimentary organic carbon stock in Coringa mangroves. The value of total organic carbon (TOC) ranges from 0.63 to 2.76% with a mean value of 1.30±4.3%. The value of total nitrogen (TN) varies from 0.04 to 0.19% with an average value of 0.08±0.03%. Dry Bulk Density (DBD) ranges from 0.63 to 2.58 gm cm-3 with a mean value of 1.33±0.19 gm cm-3. The mean value of sedimentary carbon stock (SCS) in Coringa mangrove is 158±32.60 Mg C ha-1. This amounts to the below-ground sedimentary carbon stock being 1.86 Tg C and represents the equivalent CO2 emission of 579.9 Mg CO2e ha-1. The TOC, TN, DBD, and SCS show significant spatial variation among the different sites. The maximum carbon stock is found in densely vegetated Coringa mangroves, followed by moderately vegetated Gaderu mangroves and the least is found in the degraded forest of Matlapalem mangroves. Grain size parameters signify that there is no definite relationship between the organic carbon content and the abundance of finer sediments fractions in the Coringa mangrove. The higher carbon stock in Coringa mangroves reveals their importance in storing carbon and hence could have relevance on a national scale too and play an important role in climate change mitigation

Boosting climate change mitigation potential of perennial lignocellulosic crops grown on marginal lands

Abstract Nitrogen fertilizer (NF) is a major uncertainty surrounding the greenhouse gas (GHG) emissions of lignocellulosic biofuels. NF enhances agronomic yields and soil C inputs via plant litters, but results in soil organic carbon (SOC) decomposition, soil N2O fluxes, and a large fossil energy footprint. Thus, whether NF is beneficial or detrimental to the GHG mitigation of biofuels is unknown. Here we show the potential GHG mitigation of fertilizing switchgrass (Panicum virgatum) at the NF rate that minimizes net GHG emissions across 7.1 million ha of marginal lands in the Midwest US, with long-term production advantages surpassing emitted GHG by 0.66 Mg CO2e ha-1 yr-1 on the aggregate. Marginal lands limited by poor N fertility could see a much greater benefit, but not SOC-rich lands, limited by low precipitation, or short growing seasons. The objectives of maximizing yield and minimizing GHG overlap only in a few environments, suggesting that maximum yield will reduce the climate benefit of cellulosic biofuels.

Bunker Oksigen Dan Karbon (Bok) Di Lingkungan Sekolah Sebagai Penyimpan Karbon, Manfaat, Dan Nilai Ekonominya

The impacts of pollution and climate change occurred in global and local communities, including at school environment. Uncomfortable school environment due to pollution and school damage due to sea-level rise interferes with learning processes and reduces students' academic performance. A new approach of a school greening programme called Bunkers of Oxygen and Carbon (BOCs) was developed in a public school (SMA Negeri 3 Merauke) in Merauke, Papua using a thematic approach to mitigate pollution and climate change. The research showed that carbon storage of BOCs is mean 74 Mg ha-1 . This is equal with carbon dioxide equivalent (CO2e) of mean 271 Mg CO2e ha-1. The capacity of BOCs as carbon storage can be optimized due to the age of vegetation in BOCs is only four years old, and below ground carbon stock was measured only up to 50 cm depth. The amount of carbon stock in BOCs was influenced by vegetation health (tree density and canopy coverage) and vegetation structure (tree diameter and height) in the BOCs (r2 = 0.56, p = 0.001). The mean economic value of carbon stocks in the BOCs was US $ 189 billion ha-1. This economic value may underestimate as many benefits and functions of the BOCs were excluded from the calculation. BOCs have ecological functions as a habitat for many wildlife species, various ecosystem services, recreational areas, aesthetic values, oxygen supply, and a place to improve creativity and as natural laboratories for practice and learning from nature. Therefore, the development of BOCs in the school environment across Indonesia is important as the functions and benefits are crucial to mitigate pollution and climate change, improve the learning process and the quality of national education.

Integrated Life Cycle Assessment for Sustainable Remediation of Contaminated Agricultural Soil in China.

Agricultural land degradation is posing a serious threat to global food security. Restoration of the degraded land has traditionally been viewed as an inherently sustainable practice; however, restoration processes render consequential environmental impacts which could potentially exceed the benefit of restoration itself. In the present study, an integrated life cycle assessment analysis was conducted to evaluate life cycle primary, secondary, and tertiary impacts associated with the restoration of the contaminated agricultural land. The results demonstrated the importance of including spatially differentiated impacts associated with managing the land and growing crops. Comparing four risk management scenarios at a contaminated field in Southern China, it was found that the primary and secondary impacts followed the order of no action > chemical stabilization > phytoextraction > alternative planting. However, when tertiary impacts were taken into account, alternative planting rendered much higher footprint in comparison with phytoextraction and chemical stabilization, which provides evidence against an emerging notion held by some policy makers. Furthermore, assuming that the loss of the rice paddy field in Southern China is compensated by the deforested land in the Amazon rainforest, the total global environmental impact would far exceed that of no action, resulting in 687 ton CO2-e ha-1 of climate change impact. Overall, the present study provides new research findings to support more holistic policy making and also sheds lights on the future development of various restoration technologies.

Tillage effects on energy use and greenhouse gas emission in wheat-cotton rotation

Crop production process utilizes input energy and produces some biomass energy as output. During this process, greenhouse gases (GHGs) are also emitted which can make environmental risks. In this study, input and output energies, energy indices, and GHG emissions arising from inputs were estimated for wheat-cotton rotation under different tillage practices in Fars province. The study was conducted as a randomized complete plot experimental design with three tillage treatments and four replicates. Tillage methods included conventional tillage (CT), reduced tillage (RT), and no tillage (NT). Results showed that NT and RT decreased energy consumption in wheat and cotton production by 1.53 and 1.19%, respectively as compared to the CT due to less fuel and machinery utilization. More than 72% of energy requirement for wheat and cotton production was consumed by irrigation water and electricity for pumping irrigation water in all tillage methods. Conventional tillage resulted in the highest output energy, energy ratio, and energy productivity in wheat-cotton rotation compared to RT and NT. Total GHG emissions for wheat and cotton production were estimated to be 51829, 51608, and 51529 kg CO2e ha-1 in CT, RT, and NT, respectively indicating that NT and RT slightly reduced GHG emission compared to CT (0.6 and 0.4%, respectively). Results of this study indicated that irrigation showed the highest share in total energy requirement and GHG emission of wheat and cotton production in semi-arid climate condition of Fars province; therefore, total input energy and GHG emissions could be markedly reduced by using more efficient irrigation systems.

Potential greenhouse gas reductions from Natural Climate Solutions in Oregon, USA.

Increasing concentrations of greenhouse gases (GHGs) are causing global climate change and decreasing the stability of the climate system. Long-term solutions to climate change will require reduction in GHG emissions as well as the removal of large quantities of GHGs from the atmosphere. Natural climate solutions (NCS), i.e., changes in land management, ecosystem restoration, and avoided conversion of habitats, have substantial potential to meet global and national greenhouse gas (GHG) reduction targets and contribute to the global drawdown of GHGs. However, the relative role of NCS to contribute to GHG reduction at subnational scales is not well known. We examined the potential for 12 NCS activities on natural and working lands in Oregon, USA to reduce GHG emissions in the context of the state's climate mitigation goals. We evaluated three alternative scenarios wherein NCS implementation increased across the applicable private or public land base, depending on the activity, and estimated the annual GHG reduction in carbon dioxide equivalents (CO2e) attributable to NCS from 2020 to 2050. We found that NCS within Oregon could contribute annual GHG emission reductions of 2.7 to 8.3 MMT CO2e by 2035 and 2.9 to 9.8 MMT CO2e by 2050. Changes in forest-based activities including deferred timber harvest, riparian reforestation, and replanting after wildfires contributed most to potential GHG reductions (76 to 94% of the overall annual reductions), followed by changes to agricultural management through no-till, cover crops, and nitrogen management (3 to 15% of overall annual reductions). GHG reduction benefits are relatively high per unit area for avoided conversion of forests (125-400 MT CO2e ha-1). However, the existing land use policy in Oregon limits the current geographic extent of active conversion of natural lands and thus, avoided conversions results in modest overall potential GHG reduction benefits (i.e., less than 5% of the overall annual reductions). Tidal wetland restoration, which has high per unit area carbon sequestration benefits (8.8 MT CO2e ha-1 yr-1), also has limited possible geographic extent resulting in low potential (< 1%) of state-level GHG reduction contributions. However, co-benefits such as improved habitat and water quality delivered by restoration NCS pathways are substantial. Ultimately, reducing GHG emissions and increasing carbon sequestration to combat climate change will require actions across multiple sectors. We demonstrate that the adoption of alternative land management practices on working lands and avoided conversion and restoration of native habitats can achieve meaningful state-level GHG reductions.

Agricultural carbon footprint is farm specific: Case study of two organic farms

Making reliable inferences from agricultural carbon footprint (aCF) estimates require increased understanding of factors behind differences in carbon footprint (CF) of different farms and systems. Establishing sources and drivers of differences in aCF accounting can improve the level of accuracy of aCF modeling and help identify meaningful areas for decision-making for greenhouse gas mitigation efforts. Currently, a lack of consideration for different styles, sizes and location of organic farms in many studies comparing CF for agricultural products from organic and conventional farming systems limit our understanding of the factors behind the observed inconsistencies in their results. This study used OFoot tool, a Life Cycle Assessment and CropSyst based carbon footprint calculator for organic farms, to estimate the aCF of two certified organic farms growing several crops in common; one is a small-scale farm located in a maritime climate and the other is a large-scale farm located in a semi-arid climate. The study identified the hotspots of each farm's CF and the underlying reasons for differences in hotspots of the two farms and those of two mutual crops, onion and winter squash, grown by the farms.The CF of the small scale and the large scale farms were 7144 and 3410 kg CO2e ha-1 yr-1 respectively. Identified hotspots differ between the two farms as well. Critical CF hotspots in the small scale farm were fuel use (47.6%), greenhouse facilities (11.3%), and net soil emissions (10.3%), whereas those in the large scale farm were electricity used for irrigation (47.5%), fuel use (26.1%), and soil amendments (20.1%). The estimated CFs of onion and winter squash produced in the small scale farm were 0.188 and 0.276 kg CO2e per kg of crops, respectively, whereas the CFs of the same crops produced in the large-scale farm were 0.05 and 0.07 kg CO2e per kg of crops, respectively. This study identified farm size and site-specific soil and climatic conditions as factors influencing decision-making that have great impact on agricultural CF of the whole farms and individual crops of onion and squash. This study reiterates the importance of using site-specific emission factors in developing models and tools for aCF estimation and echoes the need for whole-farm CF analysis in understanding the context behind major hotspots in the CF of farms and farms products.

Comparison of Greenhouse Gas Offset Quantification Protocols for Nitrogen Management in Dryland Wheat Cropping Systems of the Pacific Northwest

In the carbon market, greenhouse gas (GHG) offset protocols need to ensure that emission reductions are of high quality, quantifiable and real. Lack of consistency across protocols for quantifying emission reductions compromise the credibility of offsets generated. Thus, protocol quantification methodologies need to be periodically reviewed to ensure emission offsets are credited accurately and updated to support practical climate policy solutions. Current GHG emission offset credits generated by agricultural nitrogen (N) management activities are based on reducing the annual N fertilizer application rate for a given crop without reducing yield. We performed a “road test” of agricultural N management protocols to evaluate differences among protocol components and quantify nitrous oxide (N2O) emission reductions under sample projects relevant to N management in dryland, wheat-based cropping systems of the inland Pacific Northwest (iPNW). We evaluated five agricultural N management offset protocols applicable to North America: two methodologies of American Carbon Registry (ACR1 and ACR2), Verified Carbon Standard (VCS), Climate Action Reserve (CAR), and Alberta Offset Credit System (Alberta). We found that only two protocols, ACR2 and VCS, were suitable for this study, in which four sample projects were developed representing feasible N fertilizer rate reduction activities. The ACR2 and VCS protocols had identical baseline and project emission quantification methodologies resulting in identical emission reduction values. Reducing N fertilizer application rate by switching to variable rate N (sample projects 1-3) or split N application (sample project 4) management resulted in a N2O emission reduction ranging from 0.07 to 0.16 and 0.26 Mg CO2e ha-1, respectively. Across the range of C prices considered ($5, $10, and $50 per metric ton of CO2 equivalent), we concluded that the N2O emission offset payment alone ($0.35 to $13.0 ha-1) was unlikely to encourage a change in fertilizer N management; however, the fertilizer cost savings from adopting variable or split N management would incentivize adopting these practices. Therefore, the monetary incentive of adopting agricultural N management BMPs for reducing N2O emission should be tied to other co-benefits and existing conservation programs to encourage N rate reductions that do not limit yield, crop quality, or economic stability.

Carbon Dioxide Equivalent Emissions of Newly Developed Rice Varieties

Breeding of rice varieties with low carbon dioxide equivalent (CO2e) emission is essential in reducing global greenhouse gas (GHG) emissions. In this study, we compared the gross CO2e emission of two newly developed green super rice (GSR) varieties with elite hybrids and nationally released farmer-cultivated varieties from production to post-production in the dry and wet seasons in Laguna, Philippines. The average gross CO2e emission was 17.9 tons CO2e ha-1 or 2.98 tons CO2e ton-1 rice (production 82%, post-production 18%). Contributing to this total were soil emissions at 72%, the use of chemicals at 5%, burning of rice straw at 3%, cooking at 12%, and transportation at 5%. The average social cost of carbon (SCC) per ton of rice was estimated at $119. Increasing grain yield per unit area with shorter growth duration decreased CO2e emission of rice per unit of weight. Cultivation of rice varieties GSR8 and GSR2 emitted 37.0% lower CO2e than the popular inbred varieties.

A bioeconomic analysis of the carbon sequestration potential of agroforestry systems: A case study of Grevillea robusta in South Western Uganda

Grevillea robusta is an agroforestry tree species that has been widely promoted under the carbon forestry schemes in South Western Uganda. The objective of the study was to estimate the amount of carbon sequestered and the profitability of carbon offsets in G. robusta woodlot and agroforestry management options under the Plan Vivo system and small-scale Clean Development Mechanism (CDM). An allometric equation for G. robusta was used to calculate the carbon stocks and merchantable wood volume in the woodlot and agroforestry management options over different crediting periods. The results indicated that G. robusta woodlots and agroforestry management options sequestered 470 and 225 t CO2e ha-1 respectively, over a 20 year rotation. The net present values (NPVs) of the G. robusta agroforestry management option of US$4367 and 4447 ha-1 under the Plan Vivo and small-scale CDM, respectively, were higher than US$1358 and 1902 ha-1 in the G. robusta woodlot management option. The NPV of the traditional agroforestry system was US$ 3992 ha-1. These results show that, whereas the woodlot option stores more carbon, it is the least profitable option. Analysis also revealed that, although poor households were well represented in the Plan Vivo scheme, they preferred the agroforestry option. This suggests that forest carbon offsets on productive agricultural land, should focus on promoting agroforestry technologies in order to increase profitability and targeting of the poor households. Key words: Allometric equation, carbon offsets, profitability

Climate regulation, energy provisioning and water purification: Quantifying ecosystem service delivery of bioenergy willow grown on riparian buffer zones using life cycle assessment.

Whilst life cycle assessment (LCA) boundaries are expanded to account for negative indirect consequences of bioenergy such as indirect land use change (ILUC), ecosystem services such as water purification sometimes delivered by perennial bioenergy crops are typically neglected in LCA studies. Consequential LCA was applied to evaluate the significance of nutrient interception and retention on the environmental balance of unfertilised energy willow planted on 50-m riparian buffer strips and drainage filtration zones in the Skåne region of Sweden. Excluding possible ILUC effects and considering oil heat substitution, strategically planted filter willow can achieve net global warming potential (GWP) and eutrophication potential (EP) savings of up to 11.9Mg CO2e and 47kg PO4e ha-1 year-1, respectively, compared with a GWP saving of 14.8Mg CO2e ha-1 year-1 and an EP increase of 7kg PO4e ha-1 year-1 for fertilised willow. Planting willow on appropriate buffer and filter zones throughout Skåne could avoid 626Mgyear-1 PO4e nutrient loading to waters.

Comparatives Study of Soil Organic Carbon (SOC) under Forest, Cultivated and Barren Land: A Case of Chovar Village, Kathmandu

The study was carried out in Chovar village of Kritipur Municipality, Kathmandu to compare the soil organic carbon (SOC) of three main land use types namely forest, agricultural and barren land and to show how land use and management are among the most important determinants of SOC stock. Stratified random sampling method was used for collecting soil samples. Walkley and Black method was applied for measuring SOC. Land use and soil depth both affected SOC stock significantly. Forest soil had higher SOC stock (98 t ha-1) as compared to agricultural land with 36.6 t ha-1 and barren land with 83.6 t ha-1. Similarly, the SOC in terms of CO22-1, 79.27 to 22.02 CO2-e ha-1 and 121.11 to 80.74 CO2-1 for 0- 20 cm to 40-60 cm soil depth, respectively. Bulk density (BD) was found less in forest soil compared to other lands at all depths, which showed negative correlation with SOC. The study showed a dire need to increase current soil C stocks which can be achieved through improvements in land use and management practices, particularly through conservation and restoration of degraded forests and soils. DOI: http://dx.doi.org/10.3126/njst.v14i2.10422 Nepal Journal of Science and Technology Vol. 14, No. 2 (2013) 103-108

Carbon Footprint of Spring Maize Production System on State-Operated Farm in Northeast China Plain

In order to calculate the carbon footprint of agricultural production on farm, this paper, based on the investigation data of the farmers production, applying carbon footprint model, evaluated the carbon footprint (CF) of spring maize production systems (SMPS) on farm and its production teams in Northeast China Plain. The results were as follows: the CF of SMPS was 863.14.42±104.17 kg CO2e ha-1, in which chemical fertilizer accounted for 44.60%, mechanical operation accounted for 42.96%, seed accounted for 9.96%, and pesticides accounted for about 2.48%, respectively. The CF of SMPS in different production teams were significantly different (P&lt;0.01), 18th production teams was the highest (958.37±81.73 kg CO2e ha-1) and 19th team was the lowest (767.84±45.98 kg CO2e ha-1). The differences of the CF of SMPSR among production teams almost was resulted from nitrous fertilizer using. Therefore, it had the potentiality of emission reduction in the production teams with higher CF. Using a fertilizer-saving way to build a low-carbon agricultural cropping pattern, that is an important way to realize agricultural energy saving and emission reduction of farm in the Northeast China Plain.