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Berlin Brandenburg

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  • 1
    In: Global Change Biology, February 2017, Vol.23(2), pp.955-965
    Description: Subsoils contain large amounts of organic carbon which is generally believed to be highly stable when compared with surface soils. We investigated subsurface organic carbon storage and dynamics by analysing organic carbon concentrations, fractions and isotopic values in 78 samples from 12 sites under different land‐uses and climates in eastern Australia. Despite radiocarbon ages of several millennia in subsoils, contrasting native systems with agriculturally managed systems revealed that subsurface organic carbon is reactive on decadal timeframes to land‐use change, which leads to large losses of young carbon down the entire soil profile. Our results indicate that organic carbon storage in soils is input driven down the whole profile, challenging the concept of subsoils as a repository of stable organic carbon.
    Keywords: Agriculture ; Climate ; Deep Soil Carbon ; Fractions ; Land‐Use Change ; Radiocarbon
    ISSN: 1354-1013
    E-ISSN: 1365-2486
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  • 2
    Language: English
    In: Biology and Fertility of Soils, Nov, 2013, Vol.49(8), p.1015(12)
    Description: Byline: Eleanor Hobley (1,2), Garry R. Willgoose (1), Silvia Frisia (2), Geraldine Jacobsen (3) Keywords: Soil organic carbon; Stabilization; Charcoal; Radiocarbon; Fractions Abstract: Soil organic carbon (SOC) content and radiocarbon concentration were measured in three particle-size fractions and charcoal fragments at four depths to bedrock in a sandy soil from SE Australia. SOC content declined with depth for all fractions. The enrichment factors of SOC showed that the finest particles are most important for SOC storage throughout the soil profile, and their importance for SOC storage increased with depth. In the topsoil, all particle-size fractions contained modern SOC. In contrast, charcoal from this depth gave radiocarbon ages of 85--165 years Before Present (BP). This difference was more pronounced at 30--60 cm, where the charcoal was dated at 2,540 years BP, over 12 times as old as the youngest fraction at that depth. These results confirm charcoal as a highly stable form of SOC. The radiocarbon data in the topsoil and near bedrock indicate that neither microaggregation nor mineral association is important for SOC stability in this soil. At intermediate sampling depths, the mid-sized fraction was the oldest. We believe that this is the result of charcoal accumulation in this fraction, inducing a shift in radiocarbon age. However, near bedrock (100--120 cm), radiocarbon concentration did not differ significantly between fractions, despite greater SOC retention in smaller fractions. In addition, radiocarbon ages at 100--120 cm indicate that charcoal is not present at this depth. We propose that environmental and soil conditions (substrate limitation, water and oxygen availability, and temperature) are responsible for the stabilization of SOC at this depth, where SOC concentrations were very low (0.1--0.3 %). Our results demonstrate that, although fine particles retain more SOC than coarse ones, they do not stabilize SOC in this sandy soil. Instead, environmental (bushfires and climate) and site factors (soil texture and soil mineralogy) control the distribution and stability of SOC throughout the soil profile. Author Affiliation: (1) School of Engineering, The University of Newcastle, Callaghan, 2308, NSW, Australia (2) School of Environmental and Life Sciences, The University of Newcastle, Callaghan, 2308, NSW, Australia (3) Institute for Environmental Research, Australian Nuclear Science and Technology Organization, Lucas Heights, Australia Article History: Registration Date: 25/03/2013 Received Date: 28/11/2012 Accepted Date: 25/03/2013 Online Date: 16/04/2013
    Keywords: Soil Mineralogy ; Soil Carbon
    ISSN: 0178-2762
    Source: Cengage Learning, Inc.
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  • 3
    Language: English
    In: Science of the Total Environment, 01 January 2017, Vol.575, pp.41-49
    Description: Fire alters ecosystem carbon cycling and generates pyrogenic matter such as charcoal, which can be incorporated into soils. The incorporation and cycling of charcoal in soils is a potential carbon sink, but studies investigating charcoal and carbon dynamics in soils are still lacking. We investigated soil carbon, charcoal and nitrogen dynamics in the top 20 cm of a sandy soil within a eucalypt forest in eastern Australia at three sites representing a chronosequence from 3 months to 14 years post-fire. In the short-term, fire removed litter, but resulted in an increase in both the charcoal and non-charcoal SOC content of the soils, which we attribute to above-ground charcoal generation and its incorporation into the soil profile, as well as below-ground root mortality. On a decadal timeframe, charcoal was preferentially retained in the sandy soil, in which other stabilisation mechanisms are limited, so that the influx of dead root carbon had no remnant effects. The incorporation and retention of charcoal in the soil profile is highly important to carbon cycling in such sandy soils with high fire frequency. It is highly likely that these effects are not limited to the upper 20 cm of soil and future studies should investigate deep soil charcoal cycling.
    Keywords: Fire ; Charcoal ; Soil Organic Carbon ; Soil Nitrogen ; Slope ; Depth Distribution ; Environmental Sciences ; Biology ; Public Health
    ISSN: 0048-9697
    E-ISSN: 1879-1026
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  • 4
    Language: English
    In: Agriculture, Ecosystems and Environment, 01 May 2016, Vol.223, pp.152-166
    Description: We investigated the stability of whole profile soil organic carbon (SOC) based upon three mid-infrared predicted fractions – particulate organic carbon (POC), humus organic carbon (HOC) and resistant organic carbon (ROC) – at 100 sites across eastern Australia. Our aim was to identify the controls on SOC stability down the whole soil profile, in particular relating to climate, site and human influences. To do this we used three data-mining algorithms (randomForests, gradient boosting machines and multiplicative adaptive regression splines) to identify and assess the controls on the relative proportions of the three fractions down the soil profile. Depth was the key influence on all three fractions, with the proportion of POC decreasing, and the proportion of HOC carbon increasing with increasing depth. SOC was strongly linked with POC, suggesting that the soils in the region are input driven. HOC and ROC were controlled additionally by climate and soil physico-chemical properties (e.g. clay content, pH), with SOC being less important to these fractions. Human influences (land-use and management) were not important to the proportion of the fractions, implying that the controls humans can exert on SOC stability in these environments may be limited.
    Keywords: Land-Use ; Climate ; Machine Learning ; Randomforests ; Gradient Boosting Machines ; Multiplicative Adaptive Regression Splines ; Agriculture ; Environmental Sciences
    ISSN: 0167-8809
    E-ISSN: 1873-2305
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  • 5
    Language: English
    In: Plant and Soil, 2015, Vol.390(1), pp.111-127
    Description: Aims: Drivers of soil organic carbon (SOC) storage are likely to vary in importance in different regions and at different depths due to local factors influencing SOC dynamics. This paper explores the factors influencing SOC to a depth of 30 cm in eastern Australia. Methods: We used a machine learning approach to identify the key drivers of SOC storage and vertical distribution at 1401 sites from New South Wales, Australia. We then assessed the influence of the identified factors using traditional statistical approaches. Results: Precipitation was important to and positively associated with SOC content, whereas temperature was important to and negatively associated with SOC vertical distribution. The importance of geology to SOC content increased with increasing soil depth. Land-use was important to both SOC content and its vertical distribution. Conclusion: We attribute these results to the influence of precipitation on primary production controlling SOC content, and the stronger influence of temperature on microbial activity affecting SOC degradation and vertical distribution. Geology affects SOC retention below the surface. Land-use controls SOC via production, removal and vertical mixing. The factors driving SOC storage are not identical to those driving SOC vertical distribution. Changes to these drivers will have differential effects on SOC storage and depth distribution.
    Keywords: Machine learning ; Vertical distribution ; Land-use ; Climate ; Geology
    ISSN: 0032-079X
    E-ISSN: 1573-5036
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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: Agriculture, Ecosystems and Environment, 01 October 2018, Vol.265, pp.363-373
    Description: Enhancing global soil organic carbon storage by 4 per mille (‰) per annum would be enough to halt current net greenhouse gas emissions, but this goal seems lofty for conventional agriculture, which frequently results in soil organic carbon and nitrogen losses. Replacing mineral nitrogen with organic nitrogen sources may benefit soil carbon and nitrogen cycling in agricultural soils, but long-term effects are yet to be clearly demonstrated, especially in soils of high natural fertility. Here we report the effects of 34 years of legumes (crimson clover, fava beans) and non-legumes (maize) in rotation combined with different fertilization regimes (no fertilization, PK fertilization, NPK fertilization) on soil carbon and nitrogen storage throughout the uppermost meter of the soil profile. Fava beans did not enhance profile carbon storage. However, fava beans induced positive effects on subsoil nitrogen cycling, with lower subsoil nitrogen densities indicating lower nitrogen leaching potential. Incorporating a clover green mulch every 4 years enhanced organic carbon storage by an average of 4.1‰ per annum down the full meter of soil compared with a conventional maize rotation, but only combined with phosphorus and potassium fertilization. The enhancement was detected below the plough-horizon, indicating that merely sampling topsoil is insufficient to assess soil carbon dynamics in these arable soils. In contrast, maize contributed only a small portion to SOC, with subsoil C contributions negligible. These results indicate that a careful combination of long-term, site-adapted crop and fertilization management strategies can help enhance SOC storage in naturally fertile soils without apparent C deficit.
    Keywords: Legumes ; Soil Organic Carbon ; Nitrogen Cycle ; Isotopes ; Land Management ; Cropping ; Agriculture ; Environmental Sciences
    ISSN: 0167-8809
    E-ISSN: 1873-2305
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  • 8
    In: Ecosphere, January 2016, Vol.7(1), pp.n/a-n/a
    Description: Subsurface soil organic carbon () is a large but still poorly understood component of the global carbon cycle. We investigated the depth distribution of in eastern Australia, testing the hypotheses that content near the surface is linked with water availability, whereas the distribution of with depth...
    Keywords: Climate ; Conditional Inference Trees ; Cropping ; Datamining ; Gradient Boosting Machines ; Grazing ; Land Use ; Machine Learning ; Randomforests
    ISSN: 2150-8925
    E-ISSN: 2150-8925
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  • 9
    Language: English
    In: SOIL Discussions, 02/20/2018, pp.1-3
    ISSN: SOIL Discussions
    E-ISSN: 2199-3998
    Source: CrossRef
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  • 10
    Language: English
    In: SOIL, 2018, Vol.4(2), pp.169-171
    Keywords: Bulk Density ; Stocks ; Soils ; Organic Soils;
    ISSN: SOIL
    E-ISSN: 2199-398X
    E-ISSN: 21993971
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