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Örjan Berglund - One of the best experts on this subject based on the ideXlab platform.
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perspectives on agriculturally used drained Peat Soils comparison of the socioeconomic and ecological business environments of six european regions
Land Use Policy, 2020Co-Authors: Christoph Buschmann, Örjan Berglund, Kerstin Berglund, Norbert Roder, Poul Erik Laerke, Martin Maddison, Ulo Mander, Merja Myllys, Bernhard Osterburg, Jan J H Van Den AkkerAbstract:Abstract In Northern, Eastern and Central European countries, Peat Soils drained for agriculture are a considerable source of greenhouse gas emissions. Since emissions from this source have high mitigation potential, they will likely be a focus of the European Union’s future climate goals. We describe and compare the similarities and differences in the socioeconomic and ecological business environment that policy makers, planners and farmers are confronted with when developing tailored proposals for low emission land use alternatives on Peat land. The analysis is based on interviews with 33 typical farmers cultivating organic Soils and on expert group discussions held in six different Northern, Eastern and Central European regions. Based on the Social-Ecological System Framework we identify and cluster important variables. Our results show that mainly hard economic variables determine preferred land use alternatives: the productivity of resource systems, the economic value of land and market incentives. Other variables, such as the heterogeneity of users and conflicts among them, are more important with respect to the implementation of alternatives. We point out possibilities to transfer solutions between regions and discuss an institutional framework for European Union, national and regional levels for facilitating implementation potential.
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future options for cultivated nordic Peat Soils can land management and rewetting control greenhouse gas emissions
Environmental Science & Policy, 2017Co-Authors: Bjorn Klove, Örjan Berglund, Kerstin Berglund, Simon Weldon, Marja MaljanenAbstract:Management of Peat Soils is regionally important as they cover large land areas and have important but conflicting ecosystems services. A recent management trend for drained Peatlands is the control of greenhouse gases (GHG) by changes in agricultural practices, Peatland restoration or paludiculture. Due to complex antagonistic controls of moisture, water table management can be difficult to use as a method for controlling GHG emissions. Past studies show that there is no obvious relationship between GHG emission rates and crop type, tillage intensity or fertilization rates. For drained Peat Soils, the best use options can vary from rewetting with reduced emission to efficient short term use to maximize the profit per amount of greenhouse gas emitted. The GHG accounting should consider the entire life cycle of the Peatland and the socio-economic benefits Peatlands provide locally. Cultivating energy crops is a viable option especially for wet Peat Soils with poor drainage, but harvesting remains a challenge due to tractability of wet Soils. Paludiculture in lowland floodplains can be a tool to mitigate regional flooding allowing water to be stored on these lands without much harm to crops. This can also increase regional biodiversity providing important habitats for birds and moisture tolerant plant species. However, on many Peatlands rewetting is not possible due to their position in the landscape and the associated difficulty to maintain a high stable water table. While the goal of rewetting often is to encourage the return of Peat forming plants and the ecosystem services they provide such as carbon sequestration, it is not well known if these plants will grow on Peat Soils that have been altered by the process of drainage and management. Therefore, it is important to consider Peat quality and hydrology when choosing management options. Mapping of sites is recommended as a management tool to guide actions. The environmental status and socio-economic importance of the sites should be assessed both for continued cultivation but also for other ecosystem services such as restoration and hydrological functions (flood control). Farmers need advice, tools and training to find the best after-use option. Biofuels might provide a cost-efficient after use option for some sites. Peat extraction followed by rewetting might provide a sustainable option as rewetting is often easier if the Peat is removed, starting the Peat accumulation from scratch. Also this provides a way to finance the after-use. As impacts of land use are uncertain, new policies should consider multiple benefits and decisions should be based on scientific evidence and field scale observations. The need to further understand the key processes and long term effects of field scale land use manipulations is evident. The recommended actions for Peatlands should be based on local condition and socio-economic needs to outline intermediate and long term plans.
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A lysimeter study on the effect of temperature on CO2 emission from cultivated Peat Soils
Geoderma, 2010Co-Authors: Örjan Berglund, Kerstin Berglund, Leif KlemedtssonAbstract:A lysimeter method was evaluated for its suitability in gas emission studies by studying the effect of temperature on CO2 emissions (dark respiration) from cultivated Peat Soils. The study was carried out with organic Soils from two locations in Sweden, a typical cultivated fen Peat with low pH and high organic matter content (Orke) and a more uncommon fen Peat with high pH and low organic matter content (Majnegarden). A drilling method with minimal soil disturbance was used to collect 12 undisturbed soil lysimeters per site. CO2 emission was measured weekly from the vegetated lysimeters and the results were Compared with data from incubation experiments. The CO2 emissions measured in the lysimeter experiment were in the same range as those in other studies and showed a similar increase with temperature as in the incubation experiment. With climatic and drainage conditions being similar in the lysimeter experiment, differences in daytime CO2 emission rates between Soils (483 mg +/- 6.9 CO2 m(-2) h(-1) from the Orke soil and 360 +/- 7.5 mg CO2 m(-2) h(-1) from the MainegArden soil) were presumably due to soil quality differences. Q(10) values of 2.1 and 3.0 were determined in the lysimeter experiment and of 1.9 to 4.5 in the incubation experiment for Orke and Majnegarden respectively. CO2 emission data fitted well to a semi-empirical equation relating CO2 emissions to air temperature. The lysimeter method proved to be well suited for CO2 emission studies. (C) 2008 Elsevier B.V. All rights reserved. (Less)
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distribution and cultivation intensity of agricultural Peat and gyttja Soils in sweden and estimation of greenhouse gas emissions from cultivated Peat Soils
Geoderma, 2010Co-Authors: Örjan Berglund, Kerstin BerglundAbstract:Abstract Digitised maps of Quaternary deposits, 40K radiation data and Integrated Agricultural Control System databases (IACS) were used in a GIS analysis to estimate the distribution and land use of agricultural Peat and gyttja Soils in Sweden. The total area of agricultural land (cropland and pastures) in Sweden was estimated at 3,496,665 ha and 8.6% of this area (301,489 ha) was classified as agricultural Peat and gyttja Soils, with 202,383 ha of deep Peat, 50,191 ha of shallow Peat and 48,915 ha of gyttja Soils. Using detailed information on crop distribution from agricultural databases, it was possible to estimate the cultivation intensity (land use) of the agricultural land. One-quarter of the agricultural area of Peat Soils was intensively cultivated with annual crops and the remaining area was extensively used, dominated by managed grasslands and pastures. There was great variation in cultivation intensity between areas, from 50% annual crops down to 10%. The gyttja Soils were in general more intensively cultivated than the Peat Soils. The improved estimates of acreage and cultivation intensity of agricultural Peat Soils were used to calculate annual greenhouse gas emissions from subsidence data. The total carbon dioxide (CO2) emissions from Swedish agricultural Peat Soils in 2003 were estimated to be between 3100 Gg CO2 and 4600 Gg CO2, which is similar to or lower than previously reported values. Emissions of nitrous oxide (N2O) were estimated at 3.2 Gg N2O in 2003. Estimated combined total emissions of CO2 and N2O from agricultural Peat Soils in Sweden in 2003 amounted to 4000–5600 Gg CO2-equivalents, which corresponds to approximately 6–8% of the total emissions of all greenhouse gases reported by Sweden (excluding the sink for land use, land use change and forestry — LULUCF). Agricultural Peat Soils represent a minor fraction of the agricultural land in Sweden but still have a significant effect on total national greenhouse gas emissions.
Kerstin Berglund - One of the best experts on this subject based on the ideXlab platform.
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perspectives on agriculturally used drained Peat Soils comparison of the socioeconomic and ecological business environments of six european regions
Land Use Policy, 2020Co-Authors: Christoph Buschmann, Örjan Berglund, Kerstin Berglund, Norbert Roder, Poul Erik Laerke, Martin Maddison, Ulo Mander, Merja Myllys, Bernhard Osterburg, Jan J H Van Den AkkerAbstract:Abstract In Northern, Eastern and Central European countries, Peat Soils drained for agriculture are a considerable source of greenhouse gas emissions. Since emissions from this source have high mitigation potential, they will likely be a focus of the European Union’s future climate goals. We describe and compare the similarities and differences in the socioeconomic and ecological business environment that policy makers, planners and farmers are confronted with when developing tailored proposals for low emission land use alternatives on Peat land. The analysis is based on interviews with 33 typical farmers cultivating organic Soils and on expert group discussions held in six different Northern, Eastern and Central European regions. Based on the Social-Ecological System Framework we identify and cluster important variables. Our results show that mainly hard economic variables determine preferred land use alternatives: the productivity of resource systems, the economic value of land and market incentives. Other variables, such as the heterogeneity of users and conflicts among them, are more important with respect to the implementation of alternatives. We point out possibilities to transfer solutions between regions and discuss an institutional framework for European Union, national and regional levels for facilitating implementation potential.
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future options for cultivated nordic Peat Soils can land management and rewetting control greenhouse gas emissions
Environmental Science & Policy, 2017Co-Authors: Bjorn Klove, Örjan Berglund, Kerstin Berglund, Simon Weldon, Marja MaljanenAbstract:Management of Peat Soils is regionally important as they cover large land areas and have important but conflicting ecosystems services. A recent management trend for drained Peatlands is the control of greenhouse gases (GHG) by changes in agricultural practices, Peatland restoration or paludiculture. Due to complex antagonistic controls of moisture, water table management can be difficult to use as a method for controlling GHG emissions. Past studies show that there is no obvious relationship between GHG emission rates and crop type, tillage intensity or fertilization rates. For drained Peat Soils, the best use options can vary from rewetting with reduced emission to efficient short term use to maximize the profit per amount of greenhouse gas emitted. The GHG accounting should consider the entire life cycle of the Peatland and the socio-economic benefits Peatlands provide locally. Cultivating energy crops is a viable option especially for wet Peat Soils with poor drainage, but harvesting remains a challenge due to tractability of wet Soils. Paludiculture in lowland floodplains can be a tool to mitigate regional flooding allowing water to be stored on these lands without much harm to crops. This can also increase regional biodiversity providing important habitats for birds and moisture tolerant plant species. However, on many Peatlands rewetting is not possible due to their position in the landscape and the associated difficulty to maintain a high stable water table. While the goal of rewetting often is to encourage the return of Peat forming plants and the ecosystem services they provide such as carbon sequestration, it is not well known if these plants will grow on Peat Soils that have been altered by the process of drainage and management. Therefore, it is important to consider Peat quality and hydrology when choosing management options. Mapping of sites is recommended as a management tool to guide actions. The environmental status and socio-economic importance of the sites should be assessed both for continued cultivation but also for other ecosystem services such as restoration and hydrological functions (flood control). Farmers need advice, tools and training to find the best after-use option. Biofuels might provide a cost-efficient after use option for some sites. Peat extraction followed by rewetting might provide a sustainable option as rewetting is often easier if the Peat is removed, starting the Peat accumulation from scratch. Also this provides a way to finance the after-use. As impacts of land use are uncertain, new policies should consider multiple benefits and decisions should be based on scientific evidence and field scale observations. The need to further understand the key processes and long term effects of field scale land use manipulations is evident. The recommended actions for Peatlands should be based on local condition and socio-economic needs to outline intermediate and long term plans.
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A lysimeter study on the effect of temperature on CO2 emission from cultivated Peat Soils
Geoderma, 2010Co-Authors: Örjan Berglund, Kerstin Berglund, Leif KlemedtssonAbstract:A lysimeter method was evaluated for its suitability in gas emission studies by studying the effect of temperature on CO2 emissions (dark respiration) from cultivated Peat Soils. The study was carried out with organic Soils from two locations in Sweden, a typical cultivated fen Peat with low pH and high organic matter content (Orke) and a more uncommon fen Peat with high pH and low organic matter content (Majnegarden). A drilling method with minimal soil disturbance was used to collect 12 undisturbed soil lysimeters per site. CO2 emission was measured weekly from the vegetated lysimeters and the results were Compared with data from incubation experiments. The CO2 emissions measured in the lysimeter experiment were in the same range as those in other studies and showed a similar increase with temperature as in the incubation experiment. With climatic and drainage conditions being similar in the lysimeter experiment, differences in daytime CO2 emission rates between Soils (483 mg +/- 6.9 CO2 m(-2) h(-1) from the Orke soil and 360 +/- 7.5 mg CO2 m(-2) h(-1) from the MainegArden soil) were presumably due to soil quality differences. Q(10) values of 2.1 and 3.0 were determined in the lysimeter experiment and of 1.9 to 4.5 in the incubation experiment for Orke and Majnegarden respectively. CO2 emission data fitted well to a semi-empirical equation relating CO2 emissions to air temperature. The lysimeter method proved to be well suited for CO2 emission studies. (C) 2008 Elsevier B.V. All rights reserved. (Less)
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distribution and cultivation intensity of agricultural Peat and gyttja Soils in sweden and estimation of greenhouse gas emissions from cultivated Peat Soils
Geoderma, 2010Co-Authors: Örjan Berglund, Kerstin BerglundAbstract:Abstract Digitised maps of Quaternary deposits, 40K radiation data and Integrated Agricultural Control System databases (IACS) were used in a GIS analysis to estimate the distribution and land use of agricultural Peat and gyttja Soils in Sweden. The total area of agricultural land (cropland and pastures) in Sweden was estimated at 3,496,665 ha and 8.6% of this area (301,489 ha) was classified as agricultural Peat and gyttja Soils, with 202,383 ha of deep Peat, 50,191 ha of shallow Peat and 48,915 ha of gyttja Soils. Using detailed information on crop distribution from agricultural databases, it was possible to estimate the cultivation intensity (land use) of the agricultural land. One-quarter of the agricultural area of Peat Soils was intensively cultivated with annual crops and the remaining area was extensively used, dominated by managed grasslands and pastures. There was great variation in cultivation intensity between areas, from 50% annual crops down to 10%. The gyttja Soils were in general more intensively cultivated than the Peat Soils. The improved estimates of acreage and cultivation intensity of agricultural Peat Soils were used to calculate annual greenhouse gas emissions from subsidence data. The total carbon dioxide (CO2) emissions from Swedish agricultural Peat Soils in 2003 were estimated to be between 3100 Gg CO2 and 4600 Gg CO2, which is similar to or lower than previously reported values. Emissions of nitrous oxide (N2O) were estimated at 3.2 Gg N2O in 2003. Estimated combined total emissions of CO2 and N2O from agricultural Peat Soils in Sweden in 2003 amounted to 4000–5600 Gg CO2-equivalents, which corresponds to approximately 6–8% of the total emissions of all greenhouse gases reported by Sweden (excluding the sink for land use, land use change and forestry — LULUCF). Agricultural Peat Soils represent a minor fraction of the agricultural land in Sweden but still have a significant effect on total national greenhouse gas emissions.
Marja Maljanen - One of the best experts on this subject based on the ideXlab platform.
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factors controlling nitrous oxide emissions from managed northern Peat Soils with low carbon to nitrogen ratio
Soil Biology & Biochemistry, 2018Co-Authors: Maarit Liimatainen, Pertti J Martikainen, Jyrki Hytönen, Kristiina Regina, Carolina Voigt, Hlynur Oskarsson, Marja MaljanenAbstract:Abstract Managed northern Peatlands are an important source of the strong greenhouse gas nitrous oxide (N2O). However, N2O emissions from these managed Peatlands display a high spatial variability, and processes governing N2O production and emissions from these ecosystems are still not well understood. To constrain the factors regulating N2O emissions from managed northern Peat Soils, we determined a wide set of soil physical and chemical properties of Peatlands with different management histories spread across Finland, Sweden and Iceland. We included eleven Peatland sites with available in situ N2O flux data, and complemented our analyses with detailed measurements of soil nitrogen (N) cycling processes such as N2O production, gross N mineralization and gross nitrification and, in addition, soil microbial biomass. This study included drained Peatlands with different land-use types and management intensities, comprising forested, cultivated or only drained Peatlands and afforested or abandoned agricultural Peatlands. All selected Peatland sites displayed a low soil carbon to nitrogen (C/N) ratio of 15–27, traditionally used to predict high N2O emissions. Despite the narrow C/N range, the N2O emissions at our sites varied greatly within and between land-use groups, ranging from 0.03 to 2.38 g N m−2 y−1. Thus, our findings provide valuable insights into the regulatory factors underlying the variability in N2O emissions and show that a low C/N ratio in managed Peatlands cannot be used to predict high N2O emissions. Instead, our results demonstrate that higher N2O emissions are linked to higher Peat phosphorus (P) and copper (Cu) content, suggesting that low P and Cu concentrations can limit N2O production in Peat even with sufficient N availability. While known factors such as soil moisture, oxygen content and the degree of Peat humification partially explained the variability in N2O emissions, this study directly links soil P and Cu availability to N2O production processes. The availability of P and especially Cu seemed to promote nitrification activities, thereby increasing N2O production. Our study highlights the link between N2O emissions and soil P and Cu availability and the strong coupling of the soil N and P cycles in Peatlands, which is to date severely understudied.
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future options for cultivated nordic Peat Soils can land management and rewetting control greenhouse gas emissions
Environmental Science & Policy, 2017Co-Authors: Bjorn Klove, Örjan Berglund, Kerstin Berglund, Simon Weldon, Marja MaljanenAbstract:Management of Peat Soils is regionally important as they cover large land areas and have important but conflicting ecosystems services. A recent management trend for drained Peatlands is the control of greenhouse gases (GHG) by changes in agricultural practices, Peatland restoration or paludiculture. Due to complex antagonistic controls of moisture, water table management can be difficult to use as a method for controlling GHG emissions. Past studies show that there is no obvious relationship between GHG emission rates and crop type, tillage intensity or fertilization rates. For drained Peat Soils, the best use options can vary from rewetting with reduced emission to efficient short term use to maximize the profit per amount of greenhouse gas emitted. The GHG accounting should consider the entire life cycle of the Peatland and the socio-economic benefits Peatlands provide locally. Cultivating energy crops is a viable option especially for wet Peat Soils with poor drainage, but harvesting remains a challenge due to tractability of wet Soils. Paludiculture in lowland floodplains can be a tool to mitigate regional flooding allowing water to be stored on these lands without much harm to crops. This can also increase regional biodiversity providing important habitats for birds and moisture tolerant plant species. However, on many Peatlands rewetting is not possible due to their position in the landscape and the associated difficulty to maintain a high stable water table. While the goal of rewetting often is to encourage the return of Peat forming plants and the ecosystem services they provide such as carbon sequestration, it is not well known if these plants will grow on Peat Soils that have been altered by the process of drainage and management. Therefore, it is important to consider Peat quality and hydrology when choosing management options. Mapping of sites is recommended as a management tool to guide actions. The environmental status and socio-economic importance of the sites should be assessed both for continued cultivation but also for other ecosystem services such as restoration and hydrological functions (flood control). Farmers need advice, tools and training to find the best after-use option. Biofuels might provide a cost-efficient after use option for some sites. Peat extraction followed by rewetting might provide a sustainable option as rewetting is often easier if the Peat is removed, starting the Peat accumulation from scratch. Also this provides a way to finance the after-use. As impacts of land use are uncertain, new policies should consider multiple benefits and decisions should be based on scientific evidence and field scale observations. The need to further understand the key processes and long term effects of field scale land use manipulations is evident. The recommended actions for Peatlands should be based on local condition and socio-economic needs to outline intermediate and long term plans.
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Afforestation does not necessarily reduce nitrous oxide emissions from managed boreal Peat Soils
Biogeochemistry, 2011Co-Authors: Marja Maljanen, Jukka Laine, Narasinha J Shurpali, Jyrki Hytönen, Päivi Mäkiranta, Lasse Aro, Hannamaria Potila, Pertti J MartikainenAbstract:Pristine Peatlands have generally low nitrous oxide (N2O) emissions but drainage and management practices enhance the microbial processes and associated N2O emissions. It is assumed that leaving Peat Soils from intensive management, such as agriculture, will decrease their N2O emissions. In this paper we report how the annual N2O emission rates will change when agricultural Peat soil is either left abandoned or afforested and also N2O emissions from afforested Peat extraction sites. In addition, we evaluated a biogeochemical model (DNDC) with a view to explaining GHG emissions from Peat Soils under different land uses. The abandoned agricultural Peat Soils had lower mean annual N2O emissions (5.5 ± 5.4 kg N ha−1) than the Peat Soils in active agricultural use in Finland. Surprisingly, N2O emissions from afforested organic agricultural Soils (12.8 ± 9.4 kg N ha−1) were similar to those from organic agricultural Soils in active use. These emissions were much higher than those from the forests on nutrient rich Peat Soils. Abandoned and afforested Peat extraction sites emitted more N2O, (2.4 ± 2.1 kg N ha−1), than the areas under active Peat extraction (0.7 ± 0.5 kg N ha−1). Emissions outside the growing season contributed significantly, 40% on an average, to the annual emissions. The DNDC model overestimated N2O emission rates during the growing season and indicated no emissions during winter. The differences in the N2O emission rates were not associated with the age of the land use change, vegetation characteristics, Peat depth or Peat bulk density. The highest N2O emissions occurred when the soil C:N ratio was below 20 with a significant variability within the measured C:N range (13–27). Low soil pH, high nitrate availability and water table depth (50–70 cm) were also associated with high N2O emissions. Mineral soil has been added to most of the Soils studied here to improve the fertility and this may have an impact on the N2O emissions. We infer from the multi-site dataset presented in this paper that afforestation is not necessarily an efficient way to reduce N2O emissions from drained boreal organic fields.
Davey L Jones - One of the best experts on this subject based on the ideXlab platform.
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is the enzyme latch or iron gate the key to protecting soil organic carbon in Peatlands
Geoderma, 2019Co-Authors: Davey L Jones, Yuan Wen, Huadong Zang, C D Evans, D R ChadwickAbstract:Abstract Peatlands represent the largest natural terrestrial carbon (C) store, however, this C can become destabilized, particularly in response to anthropogenic disturbance or lowering of the water table. Several different paradigms have been proposed to explain the positive or negative relationships of moisture status with C loss rates in Peat Soils (e.g. ‘enzyme latch’, ‘iron gate’). The relative importance of these regulatory mechanisms and whether they are mutually exclusive, however, remain unknown. To address this, we evaluated the effects of contrasting soil moisture regime and iron concentration on organic matter mineralization in an agriculturally managed lowland fen Peat. Our results showed that for the first 50 days of incubation, phenol oxidative activity under saturated conditions (120% water holding capacity; WHC) was lower than that at 65% WHC, but after this period the pattern was reversed. These results suggest that two different mechanisms may control phenol oxidative activity simultaneously, with the dominant controlling factor and final response being dependent on the trade-offs between oxygen and Fe(II) effects. Although Fe(II) addition increased phenol oxidative activity, it suppressed SOC mineralization regardless of the soil moisture content, suggesting that iron can protect soil C from microbial decomposition in lowland Peat Soils. Our study has implications for understanding the widely divergent biogeochemical functions of soil moisture on Peat Soils and emphasizes the influence of oxygen and Fe(II) on phenol oxidative activity and SOC mineralization.
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greenhouse gas emissions from intensively managed Peat Soils in an arable production system
Agriculture Ecosystems & Environment, 2017Co-Authors: Helen E Taft, Paul C Cross, Gareth Edwardsjones, Edwin R Moorhouse, Davey L JonesAbstract:Abstract Organic-rich, eutrophic Peat Soils (Histosols) represent a major store of carbon (C) within the terrestrial biosphere. However, these Soils are also highly susceptible to damage, particularly when used for intensive agricultural production. Sustainable management of such Soils is contingent upon improved understanding of the impact of their management on the environment. In this context, we report the first annual budget of greenhouse gas emissions from temperate Peat Soils under intensive horticultural production. Fluxes of CO2, N2O and CH4 were measured using static chambers on three farms along an organic matter loss gradient (∼20%, ∼35%, and ∼70% soil organic matter (SOM) content respectively), under a number of commercially important crops in similar rotations. Cumulative annual fluxes of CO2 in fallow and cropped Soils were large and ranged from 13.0 ± 2.4 to 30.9 ± 2.5 t CO2-e ha−1 y−1, showing a general increase with SOM, and on cropped compared to bare Soils. Annual emissions of N2O varied from 5.0 ± 0.7 to 13.9 ± 1.9 t CO2-e ha−1 y−1, and CH4 from −0.02 ± 0.08 to 0.04 ± 0.02 t CO2-e ha−1 y−1; neither showed a significant relationship with either SOM content or cropping. Distinct seasonal patterns of CO2 and N2O fluxes were observed, corresponding to significant correlations between emissions and soil and air temperature, soil moisture content, water table depth, and soil nitrate on some soil types. No discernible seasonal pattern in CH4 fluxes was observed, and very few significant correlations with soil environmental variables were found. Compared to emissions estimates suggested in IPCC inventory guidelines for cultivated Peat Soils, the observed emissions in this study were relatively high, and net annual fluxes of CO2 and CH4 are equivalent to a loss of soil depth of 0.33–0.75 cm y−1. We conclude that arable farming is promoting extreme mineralization of the soil’s organic carbon reserves and that a change in land use or management regime is needed to protect and preserve this natural capital.
Alex T Chow - One of the best experts on this subject based on the ideXlab platform.
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temperature water content and wet dry cycle effects on doc production and carbon mineralization in agricultural Peat Soils
Soil Biology & Biochemistry, 2006Co-Authors: Alex T Chow, Kenneth K Tanji, Suduan Gao, Randy A DahlgrenAbstract:Abstract Agricultural Peat Soils in the Sacramento-San Joaquin Delta, California have been identified as an important source of dissolved organic carbon (DOC) and trihalomethane precursors in waters exported for drinking. The objectives of this study were to examine the primary sources of DOC from soil profiles (surface vs. subsurface), factors (temperature, soil water content and wet–dry cycles) controlling DOC production, and the relationship between C mineralization and DOC concentration in cultivated Peat Soils. Surface and subsurface Peat Soils were incubated for 60 d under a range of temperature (10, 20, and 30 °C) and soil water contents (0.3–10.0 g-water g-soil −1 ). Both CO 2 –C and DOC were monitored during the incubation period. Results showed that significant amount of DOC was produced only in the surface soil under constantly flooded conditions or flooding/non-flooding cycles. The DOC production was independent of temperature and soil water content under non-flooded condition, although CO 2 evolution was highly correlated with these parameters. Aromatic carbon and hydrophobic acid contents in surface DOC were increased with wetter incubation treatments. In addition, positive linear correlations ( r 2 =0.87) between CO 2 –C mineralization rate and DOC concentration were observed in the surface soil, but negative linear correlations ( r 2 =0.70) were observed in the subsurface soil. Results imply that mineralization of soil organic carbon by microbes prevailed in the subsurface soil. A conceptual model using a kinetic approach is proposed to describe the relationships between CO 2 –C mineralization rate and DOC concentration in these Soils.
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production of dissolved organic carbon doc and trihalomethane thm precursor from Peat Soils
Water Research, 2003Co-Authors: Alex T Chow, Kenneth K Tanji, Suduan GaoAbstract:Water passing through the Sacramento-San Joaquin Delta contains elevated concentrations of dissolved organic carbon (DOC) and trihalomethane (THM) precursor relative to upstream waters from the Sacramento River and the San Joaquin River. Drainage from agricultural Peat Soils has been identified as one of the major sources of DOC and THM precursor. A series of controlled laboratory experiments were conducted to evaluate abiotic and biotic effects on the quantity and the nature of DOC and THM precursors produced from oxidized surface and reduced subsurface Soils in the Delta. For abiotic effects, DOC was extracted from both Soils with synthetic solutions containing a range of salinity (0-4 dS/m) and sodicity (0 to infinity ). The results showed that an increase in salinity significantly decreased the concentration of DOC in the soil-water from both Soils but increased its aromaticity, as indicated by specific ultraviolet absorbance at 254 nm (SUVA). For biotic effects, Peat Soils were incubated over a range of temperatures (10 degrees C, 20 degrees C and 30 degrees C) and soil moisture contents (0.3-10 g water/g soil). After 8 weeks of incubation, only extracted DOC from flooded conditions and flooded and non-flooded cycles showed an increase in DOC. These findings indicate that neither salinity nor sodicity is the major factor for DOC production, but both can affect the solubility and mobility of DOC in the Delta Soils. We believe wetting processes in oxidized Peat Soils produce significant amounts of DOC found in agricultural drainage discharged into the Delta waters.