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Halim MA, Bieser JMH, Thomas SC. Large, sustained soil CO 2 efflux but rapid recovery of CH 4 oxidation in post-harvest and post-fire stands in a mixedwood boreal forest. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 930:172666. [PMID: 38653415 DOI: 10.1016/j.scitotenv.2024.172666] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2023] [Revised: 04/18/2024] [Accepted: 04/19/2024] [Indexed: 04/25/2024]
Abstract
The net effect of forest disturbances, such as fires and harvesting, on soil greenhouse gas fluxes is determined by their impacts on both biological and physical factors, as well as the temporal dynamics of these effects post-disturbance. Although harvesting and fire may have distinct effects on soil carbon (C) dynamics, the temporal patterns in soil CO2 and CH4 fluxes and the potential differences between types of disturbances, remain poorly characterized in boreal forests. In this study, we measured soil CO2 and CH4 fluxes using a off-axis integrated cavity output spectroscopy system in snow-free seasons over two years in post-harvest and post-fire chronosequence sites within a mixedwood boreal forest in northwestern Ontario, Canada. Soil CO2 efflux showed a post-disturbance peak, with differing dynamics depending on the disturbance type: post-harvest stands exhibited a nearly tenfold increase (from ∼1 to ∼11 μmol CO2.m-2.s-1) from 1 to 9-10 years post-disturbance, followed by a steep decline; post-fire stands showed a more gradual increase, peaking at ∼6-7.2 μmol CO2.m-2.s-1 after ∼12-15 years. The youngest post-harvest stands were net sources of CH4,whereas post-fire stands were never net CH4 sources. In both disturbance types, the strength of the CH4 sink increased with stand age, approaching ∼2.4 nmol.m-2.s-1 by 15 years post-disturbance. Volumetric water content, bulk density, litter depth, and pH were significant predictors of CO2 fluxes; for CH4 fluxes, litter depth, pH, and the interaction of VWC and soil temperature were significant predictors in both disturbance types, with EC also showing a relationship in post-harvest stands. Our findings indicate that while soil CH4 oxidation rapidly recovers following disturbance, both post-harvest and post-fire stands show a multi-decade release of soil CO2 that is too large to be offset by C gains over this period.
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Affiliation(s)
- Md Abdul Halim
- Institute of Forestry and Conservation, University of Toronto, 33 Willcocks Street, M5S 3B3 Toronto, Canada; Department of Forestry and Environmental Science, Shahjalal University of Science and Technology, Sylhet 3114, Bangladesh.
| | - Jillian M H Bieser
- Institute of Forestry and Conservation, University of Toronto, 33 Willcocks Street, M5S 3B3 Toronto, Canada
| | - Sean C Thomas
- Institute of Forestry and Conservation, University of Toronto, 33 Willcocks Street, M5S 3B3 Toronto, Canada
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Govednik A, Eler K, Mihelič R, Suhadolc M. Mineral and organic fertilisation influence ammonia oxidisers and denitrifiers and nitrous oxide emissions in a long-term tillage experiment. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 928:172054. [PMID: 38569950 DOI: 10.1016/j.scitotenv.2024.172054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 03/22/2024] [Accepted: 03/26/2024] [Indexed: 04/05/2024]
Abstract
Nitrous oxide (N2O) emissions from different agricultural systems have been studied extensively to understand the mechanisms underlying their formation. While a number of long-term field experiments have focused on individual agricultural practices in relation to N2O emissions, studies on the combined effects of multiple practices are lacking. This study evaluated the effect of different tillage [no-till (NT) vs. conventional plough tillage (CT)] in combination with fertilisation [mineral (MIN), compost (ORG), and unfertilised control (CON)] on seasonal N2O emissions and the underlying N-cycling microbial community in one maize growing season. Rainfall events after fertilisation, which resulted in increased soil water content, were the main triggers of the observed N2O emission peaks. The highest cumulative emissions were measured in MIN fertilisation, followed by ORG and CON fertilisation. In the period after the first fertilisation CT resulted in higher cumulative emissions than NT, while no significant effect of tillage was observed cumulatively across the entire season. A higher genetic potential for N2O emissions was observed under NT than CT, as indicated by an increased (nirK + nirS)/(nosZI + nosZII) ratio. The mentioned ratio under NT decreased in the order CON > MIN > ORG, indicating a higher N2O consumption potential in the NT-ORG treatment, which was confirmed in terms of cumulative emissions. The AOB/16S ratio was strongly affected by fertilisation and was higher in the MIN than in the ORG and CON treatments, regardless of the tillage system. Multiple regression has revealed that this ratio is one of the most important variables explaining cumulative N2O emissions, possibly reflecting the role of bacterial ammonia oxidisers in minerally fertilised soil. Although the AOB/16S ratio aligned well with the measured N2O emissions in our experimental field, the higher genetic potential for denitrification expressed by the (nirK + nirS)/(nosZI + nosZII) ratio in NT than CT was not realized in the form of increased emissions. Our results suggest that organic fertilisation in combination with NT shows a promising combination for mitigating N2O emissions; however, addressing the yield gap is necessary before incorporating it in recommendations for farmers.
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Affiliation(s)
- Anton Govednik
- University of Ljubljana, Biotechnical Faculty, Agronomy Department, Jamnikarjeva 101, 1000 Ljubljana, Slovenia
| | - Klemen Eler
- University of Ljubljana, Biotechnical Faculty, Agronomy Department, Jamnikarjeva 101, 1000 Ljubljana, Slovenia
| | - Rok Mihelič
- University of Ljubljana, Biotechnical Faculty, Agronomy Department, Jamnikarjeva 101, 1000 Ljubljana, Slovenia
| | - Marjetka Suhadolc
- University of Ljubljana, Biotechnical Faculty, Agronomy Department, Jamnikarjeva 101, 1000 Ljubljana, Slovenia.
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Tao B, Chen Q, Jiang Y, Zhang B, Yuan H, Wang Y. Effect of particle sizes of biochar on CO 2 emissions in a poplar plantation of ancient Yellow River channel, China. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2023; 345:118721. [PMID: 37536134 DOI: 10.1016/j.jenvman.2023.118721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Revised: 07/09/2023] [Accepted: 07/26/2023] [Indexed: 08/05/2023]
Abstract
Forest soil is a vital pool of organic carbon, which is sensitive to management. Biochar addition could change the CO2 emissions from soil, but its effects are still ambiguous. Moreover, the impacts of particle sizes of biochar on CO2 emissions are still unknown. In this study, a series of field experiments were conducted to investigate the effects of biochar addition on CO2 emissions in a poplar plantation (Populus nigra), China. Biochar with two application rates of (10 and 50 t/ha) and three particle sizes (3-1 mm, 1-0.1 mm, and <0.1 mm) was applied into the surface soil (0-10 cm), and the soil without biochar was set as control. The results showed that a high level of fine biochar addition (1-0.1 mm and <0.1 mm) had similar and positive effects on CO2 emissions by increasing the contents of soil ammonium, available phosphorus, easily oxidizable carbon, soil moisture, soil capillary pore, and the activity of β-glucosidase. However, biochar addition (1-0.1 mm and <0.1 mm) reduced the bioavailability of dissolved organic carbon (DOC), producing a negative relationship between DOC content and CO2 emissions. This investigation highlights the importance of biochar with different particle sizes in adjusting CO2 emissions from temperate soils.
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Affiliation(s)
- Baoxian Tao
- College of Geography and Environment, Liaocheng University, Liaocheng, 252059, China; Liaocheng Key Laboratory of Agricultural Soil Environment and Pollution Prevention, Liaocheng, 252059, China; Institute of Huanghe Studies, Liaocheng University, Liaocheng, 252059, China.
| | - Qinghai Chen
- College of Geography and Environment, Liaocheng University, Liaocheng, 252059, China
| | - Yuqing Jiang
- College of Humanities and Social Science, Lyceum of the Philippines University, Batangas, 4200, Philippines
| | - Baohua Zhang
- College of Geography and Environment, Liaocheng University, Liaocheng, 252059, China; Liaocheng Key Laboratory of Agricultural Soil Environment and Pollution Prevention, Liaocheng, 252059, China; Institute of Huanghe Studies, Liaocheng University, Liaocheng, 252059, China
| | - Haiyan Yuan
- College of Geography and Environment, Liaocheng University, Liaocheng, 252059, China; Liaocheng Key Laboratory of Agricultural Soil Environment and Pollution Prevention, Liaocheng, 252059, China; Institute of Huanghe Studies, Liaocheng University, Liaocheng, 252059, China
| | - Yujiao Wang
- College of Geography and Environment, Liaocheng University, Liaocheng, 252059, China
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Barczyk L, Kuntu-Blankson K, Calanca P, Six J, Ammann C. N 2O emission factors for cattle urine: effect of patch characteristics and environmental drivers. NUTRIENT CYCLING IN AGROECOSYSTEMS 2023; 127:173-189. [PMID: 37846228 PMCID: PMC10576711 DOI: 10.1007/s10705-023-10290-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 05/23/2023] [Indexed: 10/18/2023]
Abstract
Urine patches from grazing cattle are hotspots of nitrous oxide (N2O) emissions. The default IPCC emission factor for urine patches (EFurine) is 0.77% for wet climates and 0.32% for dry climates. However, literature reports a considerable range of cattle urine EF values and urine characteristics used in experimental studies, revealing contrary results on the effects of urine patch characteristics and seasonal pattern. Therefore, we examined N2O emissions and corresponding EFurine values in relation to urine patch characteristics (urine N concentration, urine volume, patch area, urine composition) and environmental drivers (precipitation, water filled pore space, soil temperature). Ten artificial urine application experiments were performed from July 2020 to June 2022 on a pasture located in Eastern Switzerland. Urine N concentration, patch area, volume and urine N composition showed no significant effects on the EFurine value (p > 0.05). EFurine varied, however, strongly over time (0.17-2.05%). A large part of the variation could be predicted either by cumulative precipitation 20 days after urine application using a second order polynomial model (Adj. R2 = 0.60) or average WFPS 30 days after urine application using a linear model (Adj. R2 = 0.45). The derived precipitation model was used to simulate EFurine weekly over the last 20 years showing no significant differences between the seasons of a year. The resulting overall average EFurine was 0.67%. More field studies are needed across sites/regions differing in climate and soil properties to implement a country-specific EF3 for Switzerland and to improve the quantification of N2O emissions at the national scales.
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Affiliation(s)
- Lena Barczyk
- Climate and Agriculture Group, Agroscope Research Station, Reckenholzstrasse 191, 8046 Zurich, Switzerland
- Department of Environmental Systems Science, ETH Zürich, Universitätstrasse 2, 8092 Zurich, Switzerland
| | - Kate Kuntu-Blankson
- Climate and Agriculture Group, Agroscope Research Station, Reckenholzstrasse 191, 8046 Zurich, Switzerland
- Department of Environmental Systems Science, ETH Zürich, Universitätstrasse 2, 8092 Zurich, Switzerland
| | - Pierluigi Calanca
- Climate and Agriculture Group, Agroscope Research Station, Reckenholzstrasse 191, 8046 Zurich, Switzerland
| | - Johan Six
- Department of Environmental Systems Science, ETH Zürich, Universitätstrasse 2, 8092 Zurich, Switzerland
| | - Christof Ammann
- Climate and Agriculture Group, Agroscope Research Station, Reckenholzstrasse 191, 8046 Zurich, Switzerland
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Berendt J, Jurasinski G, Wrage-Mönnig N. Influence of rewetting on N 2O emissions in three different fen types. NUTRIENT CYCLING IN AGROECOSYSTEMS 2022; 125:277-293. [PMID: 36373007 PMCID: PMC9638291 DOI: 10.1007/s10705-022-10244-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Accepted: 10/21/2022] [Indexed: 06/16/2023]
Abstract
UNLABELLED In recent years, many peatlands in Europe have been rewetted for nature conservation and global warming mitigation. However, the effects on emissions of the greenhouse gas nitrous oxide (N2O) have been found to be highly variable and driving factors are poorly understood. Therefore, we measured N2O fluxes every two weeks over three years on pairs of sites (one drained, one rewetted) of three important peatland types in North-Eastern Germany, namely, percolation fen, alder forest and coastal fen. Additionally, every three months, sources of N2O were determined using a stable isotope mapping approach. Overall, fluxes were under the very dry conditions of the study years usually small with large temporal and spatial variations. Ammonium concentrations consistently and significantly correlated positively with N2O fluxes for all sites. Cumulative fluxes were often not significantly different from zero and apart from the rewetted alder forest, which was always a source of N2O, sites showed varying cumulative emission behavior (insignificant, source, potentially sink in one case) among years. Precipitation was positively correlated with cumulative fluxes on all drained sites and the rewetted alder forest. Isotope mapping indicated that N2O was always produced by more than one process simultaneously, with the estimated contribution of denitrification varying between 20 and 80%. N2O reduction played a potentially large role, with 5 to 50% of total emissions, showing large variations among sites and over time. Overall, neither the effect of rewetting, water level nor seasonality was clearly reflected in the fluxes or sources. Emissions were concentrated in hotspots and hot moments. A better understanding of the driving factors of N2O production and reduction in (rewetted) fens is essential and stable isotope methods including measurements of 15N and 18O as well as site preferences can help foster the necessary comprehension of the underlying mechanisms. SUPPLEMENTARY INFORMATION The online version contains supplementary material available at 10.1007/s10705-022-10244-y.
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Affiliation(s)
- Jacqueline Berendt
- Grassland and Fodder Sciences, Faculty of Agricultural and Environmental Sciences, University of Rostock, Rostock, Germany
- Present Address: Behörde für Umwelt, Klima, Energie und Agrarwirtschaft, Hamburg, Germany
| | - Gerald Jurasinski
- Landscape Ecology, Faculty of Agricultural and Environmental Sciences, University of Rostock, Rostock, Germany
| | - Nicole Wrage-Mönnig
- Grassland and Fodder Sciences, Faculty of Agricultural and Environmental Sciences, University of Rostock, Rostock, Germany
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Gross CD, Bork EW, Carlyle CN, Chang SX. Agroforestry perennials reduce nitrous oxide emissions and their live and dead trees increase ecosystem carbon storage. GLOBAL CHANGE BIOLOGY 2022; 28:5956-5972. [PMID: 35841134 DOI: 10.1111/gcb.16322] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 06/22/2022] [Indexed: 06/15/2023]
Abstract
Agroforestry systems (AFS) contribute to carbon (C) sequestration and reduction in greenhouse gas emissions from agricultural lands. However, previously understudied differences among AFS may underestimate their climate change mitigation potential. In this 3-year field study, we assessed various C stocks and greenhouse gas emissions across two common AFS (hedgerows and shelterbelts) and their component land uses: perennial vegetated areas with and without trees (woodland and grassland, respectively), newly planted saplings in grassland, and adjacent annual cropland in central Alberta, Canada. Between 2018 and 2020 (~April-October), nitrous oxide emissions were 89% lower under perennial vegetation relative to the cropland (0.02 and 0.18 g N m-2 year-1 , respectively). In 2020, heterotrophic respiration in the woodland was 53% lower in shelterbelts relative to hedgerows (279 and 600 g C m-2 year-1 , respectively). Within the woodland, deadwood C stock was particularly important in hedgerows (35 Mg C ha-1 or 7% of ecosystem C) relative to shelterbelts (2 Mg C ha-1 or <1% of ecosystem C), and likely affected C cycling differences between the woodland types by enhancing soil labile C and microbial biomass in hedgerows. Deadwood C stock was positively correlated with annual heterotrophic respiration and total (to ~100 cm depth) soil organic C, water-soluble organic C, and microbial biomass C. Total ecosystem C was 1.90-2.55 times greater within the woodland than all other land uses, with 176, 234, 237, and 449 Mg C ha-1 found in the cropland, grassland, planted saplings treatment, and woodland, respectively. Shelterbelt and hedgerow woodlands contained 2.09 and 3.03 times more C, respectively, than adjacent cropland. Our findings emphasize the importance of AFS for fostering C sequestration and reducing greenhouse gas emissions and, in particular, retaining hedgerows (legacy woodland) and their associated deadwood across temperate agroecosystems will help mitigate climate change.
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Affiliation(s)
- Cole D Gross
- Department of Renewable Resources, Faculty of Agricultural, Life and Environmental Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Edward W Bork
- Department of Agricultural, Food and Nutritional Science, Faculty of Agricultural, Life and Environmental Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Cameron N Carlyle
- Department of Agricultural, Food and Nutritional Science, Faculty of Agricultural, Life and Environmental Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Scott X Chang
- Department of Renewable Resources, Faculty of Agricultural, Life and Environmental Sciences, University of Alberta, Edmonton, Alberta, Canada
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Tedeschi LO, Abdalla AL, Álvarez C, Anuga SW, Arango J, Beauchemin KA, Becquet P, Berndt A, Burns R, De Camillis C, Chará J, Echazarreta JM, Hassouna M, Kenny D, Mathot M, Mauricio RM, McClelland SC, Niu M, Onyango AA, Parajuli R, Pereira LGR, del Prado A, Paz Tieri M, Uwizeye A, Kebreab E. Quantification of methane emitted by ruminants: a review of methods. J Anim Sci 2022; 100:skac197. [PMID: 35657151 PMCID: PMC9261501 DOI: 10.1093/jas/skac197] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 05/31/2022] [Indexed: 11/26/2022] Open
Abstract
The contribution of greenhouse gas (GHG) emissions from ruminant production systems varies between countries and between regions within individual countries. The appropriate quantification of GHG emissions, specifically methane (CH4), has raised questions about the correct reporting of GHG inventories and, perhaps more importantly, how best to mitigate CH4 emissions. This review documents existing methods and methodologies to measure and estimate CH4 emissions from ruminant animals and the manure produced therein over various scales and conditions. Measurements of CH4 have frequently been conducted in research settings using classical methodologies developed for bioenergetic purposes, such as gas exchange techniques (respiration chambers, headboxes). While very precise, these techniques are limited to research settings as they are expensive, labor-intensive, and applicable only to a few animals. Head-stalls, such as the GreenFeed system, have been used to measure expired CH4 for individual animals housed alone or in groups in confinement or grazing. This technique requires frequent animal visitation over the diurnal measurement period and an adequate number of collection days. The tracer gas technique can be used to measure CH4 from individual animals housed outdoors, as there is a need to ensure low background concentrations. Micrometeorological techniques (e.g., open-path lasers) can measure CH4 emissions over larger areas and many animals, but limitations exist, including the need to measure over more extended periods. Measurement of CH4 emissions from manure depends on the type of storage, animal housing, CH4 concentration inside and outside the boundaries of the area of interest, and ventilation rate, which is likely the variable that contributes the greatest to measurement uncertainty. For large-scale areas, aircraft, drones, and satellites have been used in association with the tracer flux method, inverse modeling, imagery, and LiDAR (Light Detection and Ranging), but research is lagging in validating these methods. Bottom-up approaches to estimating CH4 emissions rely on empirical or mechanistic modeling to quantify the contribution of individual sources (enteric and manure). In contrast, top-down approaches estimate the amount of CH4 in the atmosphere using spatial and temporal models to account for transportation from an emitter to an observation point. While these two estimation approaches rarely agree, they help identify knowledge gaps and research requirements in practice.
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Affiliation(s)
- Luis Orlindo Tedeschi
- Department of Animal Science, Texas A&M University, College Station, TX 77843-2471, USA
| | - Adibe Luiz Abdalla
- Center for Nuclear Energy in Agriculture, University of Sao Paulo, Piracicaba CEP 13416.000, Brazil
| | - Clementina Álvarez
- Department of Research, TINE SA, Christian Magnus Falsens vei 12, 1433 Ås, Norway
| | - Samuel Weniga Anuga
- European University Institute (EUI), Via dei Roccettini 9, San Domenico di Fiesole (FI), Italy
| | - Jacobo Arango
- International Center for Tropical Agriculture (CIAT), Km 17 Recta Cali-Palmira, A.A, 6713, Cali, Colombia
| | - Karen A Beauchemin
- Agriculture and Agri-Food Canada, Lethbridge Research and Development Centre, Lethbridge, Alberta, T1J 4B1, Canada
| | | | - Alexandre Berndt
- Embrapa Southeast Livestock, Rod. Washington Luiz, km 234, CP 339, CEP 13.560-970. São Carlos, São Paulo, Brazil
| | - Robert Burns
- Biosystems Engineering and Soil Science Department, The University of Tennessee, Knoxville, TN 37996, USA
| | - Camillo De Camillis
- Animal Production and Health Division, Food and Agriculture Organization of the United Nations, Viale delle Terme di Caracalla, 00153 Rome, Italy
| | - Julián Chará
- Centre for Research on Sustainable Agriculture, CIPAV, Cali 760042, Colombia
| | | | - Mélynda Hassouna
- INRAE, Institut Agro Rennes Angers, UMR SAS, F-35042, Rennes, France
| | - David Kenny
- Teagasc Animal and Grassland Research and Innovation Centre, Grange, Dunsany, Co. Meath, C15PW93, Ireland
| | - Michael Mathot
- Agricultural Systems Unit, Walloon Agricultural Research Centre, rue du Serpont 100, B-6800 Libramont, Belgium
| | - Rogerio M Mauricio
- Department of Bioengineering, Federal University of São João del-Rei, São João del-Rei, MG 36307-352, Brazil
| | - Shelby C McClelland
- Animal Production and Health Division, Food and Agriculture Organization of the United Nations, Viale delle Terme di Caracalla, 00153 Rome, Italy
- Soil and Crop Sciences, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853, USA
| | - Mutian Niu
- Institute of Agricultural Sciences, ETH Zurich, Universitaetstrasse 2, 8092 Zurich, Switzerland
| | - Alice Anyango Onyango
- Mazingira Centre, International Livestock Research Institute (ILRI), Nairobi, Kenya
- Department of Chemistry, Maseno University, Maseno, Kenya
| | | | | | - Agustin del Prado
- Basque Centre For Climate Change (BC3), Leioa, Spain
- IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
| | - Maria Paz Tieri
- Dairy Value Chain Research Institute (IDICAL) (INTA–CONICET), Rafaela, Argentina
| | - Aimable Uwizeye
- Animal Production and Health Division, Food and Agriculture Organization of the United Nations, Viale delle Terme di Caracalla, 00153 Rome, Italy
| | - Ermias Kebreab
- Department of Animal Science, University of California, Davis, CA 95616, USA
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Gross CD, Bork EW, Carlyle CN, Chang SX. Biochar and its manure-based feedstock have divergent effects on soil organic carbon and greenhouse gas emissions in croplands. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 806:151337. [PMID: 34743889 DOI: 10.1016/j.scitotenv.2021.151337] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 10/13/2021] [Accepted: 10/26/2021] [Indexed: 06/13/2023]
Abstract
Applying organic amendments to soil can increase soil organic carbon (SOC) storage and reduce greenhouse gas (GHG) emissions generated by agriculture, helping to mitigate climate change. However, it is necessary to determine which type of amendment produces the most desirable results. We conducted a 3-y field study comparing one-time addition of manure compost and its biochar derivative to a control to assess their effects on SOC and GHG emissions at ten annually cropped sites in central Alberta, Canada. Manure compost and biochar were applied at equivalent carbon rates (7 Mg ha-1) and tilled into the surface 10 cm of soil. Two years post-treatment, biochar addition increased surface (0-10 cm) SOC by 12 and 10 Mg ha-1 relative to the control and manure addition, respectively. Therefore, biochar addition led to the sequestration of SOC at a rate of 2.5 Mg ha-1 y-1 relative to the control. No treatment effect on deeper (10-100 cm) or cumulative SOC was found. In 2018 and 2019, manure addition increased cumulative GHG (sum of CO2, CH4, and N2O) emissions by 33%, on average, due to greater CO2 emissions relative to both the control and biochar addition. In contrast, in 2020, biochar addition reduced cumulative GHG emissions by an average of 21% due to lower CO2 emissions relative to both the control and manure addition. Our study shows that the application of biochar, rather than its manure compost feedstock, increased surface SOC sequestration and had either no effect on (first two years) or reduced GHG emissions (year three) relative to the control. We recommend that policy and carbon sequestration initiatives focus on optimizing biochar production-application systems to fully realize the potential of biochar application as a viable climate change mitigation practice in agriculture.
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Affiliation(s)
- Cole D Gross
- Department of Renewable Resources, Faculty of Agricultural, Life and Environmental Sciences, University of Alberta, 442 Earth Sciences Building, Edmonton, AB T6G 2E3, Canada.
| | - Edward W Bork
- Department of Agricultural, Food and Nutritional Science, Faculty of Agricultural, Life and Environmental Sciences, University of Alberta, 410 Agriculture/Forestry Centre, Edmonton, AB T6G 2P5, Canada.
| | - Cameron N Carlyle
- Department of Agricultural, Food and Nutritional Science, Faculty of Agricultural, Life and Environmental Sciences, University of Alberta, 410 Agriculture/Forestry Centre, Edmonton, AB T6G 2P5, Canada.
| | - Scott X Chang
- Department of Renewable Resources, Faculty of Agricultural, Life and Environmental Sciences, University of Alberta, 442 Earth Sciences Building, Edmonton, AB T6G 2E3, Canada.
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Greenhouse Gas Balance of Sphagnum Farming on Highly Decomposed Peat at Former Peat Extraction Sites. Ecosystems 2021. [DOI: 10.1007/s10021-021-00659-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
AbstractFor two years, we quantified the exchange of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) at two different large-scale Sphagnum farming sites. At both, peat extraction left a shallow layer of highly decomposed peat and low hydraulic conductivities. One site was characterized by preceding multi-annual inundation and irrigated by ditches, while the other one was inoculated directly after peat extraction and irrigated by ditches and drip irrigation. Further, GHG emissions from an irrigation polder and the effect of harvesting Sphagnum donor material at a near-natural reference site were determined. GHG mitigation potentials lag behind the results of less decomposed sites, although our results were also affected by the extraordinary hot and dry summer 2018. CO2 exchanges ranged between -0.6 and 2.2 t CO2-C ha−1 y−1 and were mainly influenced by low water table depths. CH4 emissions were low with the exception of plots with higher Eriophorum covers, while fluctuating water tables and poorly developing plant covers led to considerable N2O emissions at the ditch irrigation site. The removal of the upper vegetation at the near-natural site resulted in increased CH4 emissions and, on average, lowered CO2 emissions. Overall, best plant growth and lowest GHG emissions were measured at the previously inundated site. At the other site, drip irrigation provided more favourable conditions than ditch irrigation. The size of the area needed for water management (ditches, polders) strongly affected the areal GHG balances. We conclude that Sphagnum farming on highly decomposed peat is possible but requires elaborate water management.
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Trace gas oxidizers are widespread and active members of soil microbial communities. Nat Microbiol 2021; 6:246-256. [PMID: 33398096 DOI: 10.1038/s41564-020-00811-w] [Citation(s) in RCA: 75] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 10/08/2020] [Indexed: 01/24/2023]
Abstract
Soil microorganisms globally are thought to be sustained primarily by organic carbon sources. Certain bacteria also consume inorganic energy sources such as trace gases, but they are presumed to be rare community members, except within some oligotrophic soils. Here we combined metagenomic, biogeochemical and modelling approaches to determine how soil microbial communities meet energy and carbon needs. Analysis of 40 metagenomes and 757 derived genomes indicated that over 70% of soil bacterial taxa encode enzymes to consume inorganic energy sources. Bacteria from 19 phyla encoded enzymes to use the trace gases hydrogen and carbon monoxide as supplemental electron donors for aerobic respiration. In addition, we identified a fourth phylum (Gemmatimonadota) potentially capable of aerobic methanotrophy. Consistent with the metagenomic profiling, communities within soil profiles from diverse habitats rapidly oxidized hydrogen, carbon monoxide and to a lesser extent methane below atmospheric concentrations. Thermodynamic modelling indicated that the power generated by oxidation of these three gases is sufficient to meet the maintenance needs of the bacterial cells capable of consuming them. Diverse bacteria also encode enzymes to use trace gases as electron donors to support carbon fixation. Altogether, these findings indicate that trace gas oxidation confers a major selective advantage in soil ecosystems, where availability of preferred organic substrates limits microbial growth. The observation that inorganic energy sources may sustain most soil bacteria also has broad implications for understanding atmospheric chemistry and microbial biodiversity in a changing world.
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