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  • Wiley Online Library  (9)
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  • 1
    In: Global Change Biology, February 2014, Vol.20(2), pp.653-665
    Description: Sequestration of atmospheric carbon (C) in soils through improved management of forest and agricultural land is considered to have high potential for global mitigation. However, the potential of soils to sequester soil organic carbon () in a stable form, which is limited by the stabilization of against microbial mineralization, is largely unknown. In this study, we estimated the C sequestration potential of soils in southeast Germany by calculating the potential saturation of silt and clay particles according to Hassink [ (1997) 77] on the basis of 516 soil profiles. The determination of the current content of silt and clay fractions for major soil units and land uses allowed an estimation of the C saturation deficit corresponding to the long‐term C sequestration potential. The results showed that cropland soils have a low level of C saturation of around 50% and could store considerable amounts of additional . A relatively high C sequestration potential was also determined for grassland soils. In contrast, forest soils had a low C sequestration potential as they were almost C saturated. A high proportion of sites with a high degree of apparent oversaturation revealed that in acidic, coarse‐textured soils the relation to silt and clay is not suitable to estimate the stable C saturation. A strong correlation of the C saturation deficit with temperature and precipitation allowed a spatial estimation of the C sequestration potential for Bavaria. In total, about 395 Mt CO‐equivalents could theoretically be stored in A horizons of cultivated soils – four times the annual emission of greenhouse gases in Bavaria. Although achieving the entire estimated C storage capacity is unrealistic, improved management of cultivated land could contribute significantly to mitigation. Moreover, increasing stocks have additional benefits with respect to enhanced soil fertility and agricultural productivity.
    Keywords: Agricultural Management ; Climate Change ; Mitigation ; Soil Organic Carbon Stocks ; Soil Fractionation ; Stabilization Of Soil Organic Matter
    ISSN: 1354-1013
    E-ISSN: 1365-2486
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  • 2
    In: Global Change Biology, October 2015, Vol.21(10), pp.3836-3845
    Description: Organic carbon () sequestration in degraded semi‐arid environments by improved soil management is assumed to contribute substantially to climate change mitigation. However, information about the soil organic carbon () sequestration potential in steppe soils and their current saturation status remains unknown. In this study, we estimated the storage capacity of semi‐arid grassland soils on the basis of remote, natural steppe fragments in northern China. Based on the maximum saturation of silt and clay particles 〈20 μm, sequestration potentials of degraded steppe soils (grazing land, arable land, eroded areas) were estimated. The analysis of natural grassland soils revealed a strong linear regression between the proportion of the fine fraction and its content, confirming the importance of silt and clay particles for stabilization in steppe soils. This relationship was similar to derived regressions in temperate and tropical soils but on a lower level, probably due to a lower C input and different clay mineralogy. In relation to the estimated storage capacity, degraded steppe soils showed a high saturation of 78–85% despite massive losses due to unsustainable land use. As a result, the potential of degraded grassland soils to sequester additional was generally low. This can be related to a relatively high contribution of labile , which is preferentially lost in the course of soil degradation. Moreover, wind erosion leads to substantial loss of silt and clay particles and consequently results in a direct loss of the ability to stabilize additional . Our findings indicate that the loss in semi‐arid environments induced by intensive land use is largely irreversible. Observed increases after improved land management mainly result in an accumulation of labile prone to land use/climate changes and therefore cannot be regarded as contribution to long‐term sequestration.
    Keywords: Climate Change ; Fine Fraction ; Soil Organic Carbon ; Soil Texture ; Steppe Soils
    ISSN: 1354-1013
    E-ISSN: 1365-2486
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  • 3
    In: Land Degradation & Development, April 2018, Vol.29(4), pp.875-883
    Description: Long‐term cultivation of steppe soils in a nonsustainable way caused severe soil degradation and reduced agricultural productivity in Eastern Europe, one of the world's most important areas for cereal production. In order to combat soil erosion and maintain yields, a widespread system of tree windbreaks was introduced in the 1950s, accompanied by improved agricultural practices in recent years. However, information on the effectiveness of such measures to rebuild soil organic carbon (SOC) is scarce. The objective of this study was to estimate the OC storage potential of the fine mineral fraction of degraded arable steppe soils in Moldova and to quantify SOC sequestration rates under (a) windbreaks, (b) cropland with improved crop rotation/manure application, and (c) cropland with cover cropping. Natural grassland relicts served as a reference to estimate the SOC saturation potential. Our results revealed a low SOC saturation of 50% under conventional agricultural use due to high SOC losses, indicating a high potential for SOC sequestration. Relatively high SOC sequestration rates were determined for topsoils (0–30 cm) under windbreaks (0.9 t ha yr), improved crop rotation/manure application (1.3 t ha yr), and cover cropping (1.9 t ha yr). In this regard, sequestration rates derived from OC changes of the fine fraction may be more reliable than total SOC‐based rates, particularly for windbreaks with high proportions of labile SOC. We conclude that implementation of improved agricultural management together with the maintenance of windbreaks is a promising strategy to rebuild SOC, reduce widespread soil erosion and compaction, and secure Moldova's agricultural productivity.
    Keywords: Agroforestry ; Carbon Sequestration ; Cover Crops ; Improved Crop Rotation ; Manure Application
    ISSN: 1085-3278
    E-ISSN: 1099-145X
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  • 4
    In: Global Change Biology, March 2018, Vol.24(3), pp.987-1000
    Description: Agricultural soils are widely recognized to be capable of carbon sequestration that contributes to mitigating emissions. To better understand soil organic carbon () stock dynamics and its driving and controlling factors corresponding with a period of rapid agronomic evolution from the 1980s to the 2010s in the North China Plain (), we collected data from two region‐wide soil sampling campaigns (in the 1980s and 2010s) and conducted an analysis of the controlling factors using the random forest model. Between the 1980s and 2010s, environmental (i.e. soil salinity/fertility) and societal (i.e. policy/techniques) factors both contributed to adoption of new management practices (i.e. chemical fertilizer application/mechanization). Results of our work indicate that stocks in the croplands increased significantly, which also closely related to soil total nitrogen changes. Samples collected near the surface (0–20 cm) and deeper (20–40 cm) both increased by an average of 9.4 and 5.1 Mg C ha, respectively, which are equivalent to increases of 73% and 56% compared with initial stocks in the 1980s. The annual carbon sequestration amount in surface soils reached 10.9 Tg C year, which contributed an estimated 43% of total carbon sequestration in all of China's cropland on just 27% of its area. Successful desalinization and the subsequent increases in carbon (C) inputs, induced by agricultural projects and policies intended to support crop production (i.e. reconstruction of low yield farmland, and agricultural subsidies), combined with improved cultivation practices (i.e. fertilization and straw return) since the early 1980s were the main drivers for the stock increase. This study suggests that rehabilitation of soils to reduce salinity and increase crop yields have also served as a pathway for substantial soil C sequestration. SOC stocks in the NCP croplands increased significantly; these changes were accompanied by changes in soil total nitrogen (TN). Annual carbon sequestration in surface soils reached 10.9 Tg C yr, which contributed an estimated 43% of total carbon sequestration in all of China’s cropland on just 27% of its area. Successful desalinization and the subsequent increases in carbon (C) inputs, induced by agricultural projects and policies (i.e. agricultural subsidies), combined with improved cultivation practices (i.e. fertilization, and straw return) since the early 1980s were the main drivers for this SOC stock increase.
    Keywords: Agricultural Policies ; Improved Cultivation ; N Stock Change ; Random Forest ; Soil Organic Carbon Stock Change
    ISSN: 1354-1013
    E-ISSN: 1365-2486
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  • 5
    In: Global Change Biology, July 2012, Vol.18(7), pp.2233-2245
    Description: Precise estimations of soil organic carbon () stocks are of decided importance for the detection of C sequestration or emission potential induced by land use changes. For Germany, a comprehensive, land use–specific data set has not yet been compiled. We evaluated a unique data set of 1460 soil profiles in southeast Germany in order to calculate representative stocks to a depth of 1 m for the main land use types. The results showed that grassland soils stored the highest amount of , with a median value of 11.8 kg m, whereas considerably lower stocks of 9.8 and 9.0 kg m were found for forest and cropland soils, respectively. However, the differences between extensively used land (grassland, forest) and cropland were much lower compared with results from other studies in central European countries. The depth distribution of showed that despite low concentrations in A horizons of cropland soils, their stocks were not considerably lower compared with other land uses. This was due to a deepening of the topsoil compared with grassland soils. Higher grassland stocks were caused by an accumulation of in the B horizon which was attributable to a high proportion of C‐rich Gleysols within grassland soils. This demonstrates the relevance of pedogenetic inventories instead of solely land use–based approaches. Our study indicated that cultivation‐induced depletion was probably often overestimated since most studies use fixed depth increments. Moreover, the application of modelled parameters in inventories is questioned because a calculation of stocks using different pedotransfer functions revealed considerably biased results. We recommend stocks be determined by horizon for the entire soil profile in order to estimate the impact of land use changes precisely and to evaluate C sequestration potentials more accurately.
    Keywords: Carbon Sequestration ; Land Use Change ; Pedotransfer Function ; Soil Organic Matter ; Topsoil Deepening
    ISSN: 1354-1013
    E-ISSN: 1365-2486
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  • 6
    In: Land Degradation & Development, April 2018, Vol.29(4), pp.1041-1053
    Description: The Food and Agriculture Organization considers around a quarter of global land to be degraded. Of particular concern are threats to soils in water‐limited regions, which are critical to food and economic security in countries across the globe but are under increasing pressure due to human use and climatic forcing. These soils have been used to feed and provide resources and services to human societies for millennia, with earliest land‐uses dating back to prehistoric times. With the adoption of modern, frequently unsuitable agricultural practices combined with the population pressures and shifting consumption patterns, soils in water‐limited regions have come under threat, resulting in degradation and in worst‐case scenarios, desertification. Here, we review the current state of soils in water‐limited environments and provide a guide to management for conservation and restoration of these fragile soils. Options to manage specific threats to soil functionality, namely, erosion, soil salinity, loss of functionality due to landscape homogenization, degradation of soil organic matter, and climate vulnerability are presented for specific land‐uses using a whole‐system approach management framework.
    Keywords: Drylands ; Erosion ; Landscape Homogenization ; Salinization ; Soil Organic Matter
    ISSN: 1085-3278
    E-ISSN: 1099-145X
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  • 7
    Language: English
    In: Journal of Plant Nutrition and Soil Science, June 2012, Vol.175(3), pp.434-442
    Description: The assessment of grassland degradation due to overgrazing is a global challenge in semiarid environments. In particular, investigations of beginning steppe degradation after a change or intensification of the land use are needed in order to detect and adjust detrimental land‐use management rapidly and thus prevent severe damages in these sensitive ecosystems. A controlled‐grazing experiment was established in Inner Mongolia (China) in 2005 that included ungrazed (UG) and heavily grazed plots with grazing intensities of 4.5 (HG4.5) and 7.5 (HG7.5) sheep per hectare. Several soil and vegetation parameters were investigated at all sites before the start of the experiment. Topsoil samples were analyzed for soil organic C (SOC), total N (N), total S (S), and bulk density (BD). As vegetation parameters, aboveground net primary productivity (ANPP), tiller density (TD), and leaf‐area index (LAI) were determined. After 3 y of the grazing experiment, BD increased and SOC, N, S, ANPP, and LAI significantly decreased with increasing grazing intensity. These sensitive parameters can be regarded as early‐warning indicators for degradation of semiarid grasslands. Vegetation parameters were, however, more sensitive not only to grazing but also to temporal variation of precipitation between 2006 and 2008. Contrary, soil parameters were primarily affected by grazing and resistant against climatic variations. The assessment of starting conditions in the study area and the application of defined grazing intensities is essential for the investigation of short‐term degradation in semiarid environments.
    Keywords: Steppe ; Desertification ; Soil Organic Carbon Soc ; Overgrazing ; Inner Mongolia
    ISSN: 1436-8730
    E-ISSN: 1522-2624
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  • 8
    Language: English
    In: Journal of Plant Nutrition and Soil Science, October 2019, Vol.182(5), pp.772-781
    Description: Archived soil samples are a valuable tool for any long‐term soil research. We analysed total carbon (C) and nitrogen (N) content and soil organic matter fractions in 38 archived soil samples that were stored for up to 21 years and compared air‐dried storage to frozen storage conditions. Samples include top‐ and upper subsoils, different soil texture and land use with C contents between 4.3 and 174 mg g. The results from this study reveal no changes in total C and N contents with storage time up to 21 years or type of storage (freezing . air drying). The analyses of soil physical fractions also revealed no significant differences between air‐dried stored and frozen stored samples for most samples. However, we found indications, that freezing of soil material might lead to changes in the mineral fractions for soils containing high amounts of water. Therefore, and as archiving soils in a frozen state is more expensive than storing air‐dried samples, we recommend the use of air‐dried samples for C quality analyses of archived soil samples.
    Keywords: Density Fractionation ; Long‐Term Experiments ; Soil Archive ; Soil Organic Carbon ; Storage Conditions
    ISSN: 1436-8730
    E-ISSN: 1522-2624
    Source: John Wiley & Sons, Inc.
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  • 9
    Language: English
    In: Geomechanics and Tunnelling, October 2017, Vol.10(5), pp.497-506
    Description: The finance available for the refurbishment of tunnels was around EUR 125 m. in 2014, which will increase to EUR 213 m. by 2018. DB Netz AG has a total of more than EUR 1 billion available in the medium term for the refurbishment of existing tunnels. This paper deals with the refurbishment of masonry tunnels of the DB Netz AG, Region South. The basis is the typical damage patterns of masonry tunnels, their causes and the possible refurbishment opportunities. On the Kirchberg Tunnel project, a feasibility study was carried out into possible repair measures. Based on the results of the study plans are now running. The article is supplemented by the latest state of the art rules for maintenance work in the area of tunnel construction at DB AG. The necessity of programmes for tunnelling, the necessary economic and operational constraints as well as experience with completed repairs to masonry tunnels conclude the article from the viewpoint of the owner and operator. Das bereitgestellte Finanzvolumen für die Instandsetzung von Tunneln lag 2014 bei ca. 125 Mio. Euro. Bis 2018 und fortfolgend soll stufenweise auf 213 Mio. Euro Jahresbudget aufgestockt werden. Insgesamt stehen der DB Netz AG mehr als eine Milliarde Euro im Mittelfristzeitraum für Instandsetzungsmaßnahmen an Bestandstunneln zur Verfügung. Dieser Beitrag beschäftigt sich mit der Erneuerung von Mauerwerkstunneln im Bestand der DB Netz AG, Regionalbereich Süd. Grundlage hierfür sind die typischen Schadensbilder bei Mauerwerkstunneln, deren Ursachen aufgezeigt werden. Anhand des Projekts Kirchbergtunnel wurde eine Machbarkeitsstudie für mögliche Instandsetzungsmaßnahmen durchgeführt, auf deren Basis nun die Planungen laufen. Die Notwendigkeit von Programmen bei Tunnelinstandsetzungen, die erforderlichen wirtschaftlichen und betrieblichen Randbedingungen sowie die Erfahrungen bei bereits durchgeführten Instandsetzungen bei Mauerwerkstunnel schließen aus Sicht des Bauherrn und Betreibers den Artikel ab.
    Keywords: Masonry ; Damage Patterns ; Condition Category ; Repair Variants ; Mauerwerk ; Schadensbilder ; Zustandskategorie ; Instandsetzungsvarianten ; Railway Tunnels ; Refurbishing ; Construction Works ; Eisenbahntunnel ; Sanierung ; Ausführung
    ISSN: 1865-7362
    E-ISSN: 1865-7389
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