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Berlin Brandenburg

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  • 1
    Lexicon Article
    Lexicon Article
    Language: English
    In: World Environmental History
    ISBN: 978-0-9743091-9-4
    Source: Gale Virtual Reference Library (GVRL)
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  • 2
    In: Geophysical Research Letters, 16 August 2018, Vol.45(15), pp.7588-7595
    Description: Soils with argillic horizons comprise more than 25% of the Earth's surface. Although their origin is still debated, lessivage is often invoked to explain them, but the long timescales involved hinder its direct experimental verification. We present a parsimonious model of clay transport, formulated for long timescales over which lessivage is modeled stochastically, complemented by detailed field observations. This probabilistic description allows us to predict the clay profile, the depth of the Bt horizon from the surface, and the mean clay residence time. The results are tested with field measurements at different locations in the Calhoun Critical Zone Observatory. Dimensional analysis unveils two dimensionless parameters governing lessivage dynamics, leading to a classification based on erosion rates and lessivage characteristics. We identify static and eluviated regimes, in which erosion or eluviation prevails, and an illuviated regime, in which the balance between lessivage and erosion brings about the formation of a Bt horizon. Soil clay layers (argillic horizons) play a crucial role in the ecosystem, affecting soil hydrology, fate of contaminants, and plant rooting. In spite of considerable research, their origin is still uncertain. Considerable debate remains on the role of lessivage, the transport of clay from surface to subsurface soil layers due to percolating water. Using a combination of a stochastic model with field observations, here we show that under specific climate and soil conditions, lessivage explains the formation of clay layers. These findings shed light on the potential evolution of soil profiles and properties under changing climatic and environmental conditions. A parsimonious model for long term analysis of clay translocation is developed and tested with field measurements The model predicts vertical clay profile, Bt horizon depth, and clay residence time Clay profiles are classified based on erosion rates and lessivage characteristics
    Keywords: Formation Of Clay‐Enriched Horizons ; Lessivage Model ; Clay Profiles Classification ; Bt Horizon ; Clay Translocation
    ISSN: 0094-8276
    E-ISSN: 1944-8007
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  • 3
    In: Nature, 2010, Vol.466(7306), p.558
    Description: Agronomists, for example, tend to measure yields from fields that generally range from less than 1 hectare to 200 hectares, whereas landscape ecologists may monitor the way habitats are interconnected over geographical areas of many thousands of hectares. [...] some farming systems, such as traditional...
    Keywords: Water Quality ; Genetically Altered Foods ; Soil Erosion ; Farms ; Farmers ; Sustainability ; Energy Efficiency ; Network Security;
    ISSN: 0028-0836
    E-ISSN: 14764687
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  • 4
    In: Nature, 1999, Vol.400(6739), p.56
    Description: Present understanding of the global carbon cycle is limited by uncertainty over soil-carbon dynamics super(1) super(-) super(6) . The clearing of the world's forests, mainly for agricultural uses, releases large amounts of carbon to the atmosphere (up to 2 x 10 super(1) super(5) g yr super(-) super(1) ), much of which arises from the cultivation driving an accelerated decomposition of soil organic matter super(1) super(-) super(4) . Although the effects of cultivation on soil carbon are well studied, studies of soil-carbon recovery after cultivation are limited super(4) super(-) super(1) super(1) . Here we present a four-decade-long field study of carbon accumulation by pine ecosystems established on previously cultivated soils in South Carolina, USA super(7) . Newly accumulated carbon is tracked by its distinctive super(1) super(4) C signature, acquired around the onset of forest growth from thermonuclear bomb testing that nearly doubled atmospheric super(1) super(4) CO sub(2) in the 1960s. Field data combined with model simulations indicate that the young aggrading forest rapidly incorporated bomb radiocarbon into the forest floor and the upper 60 cm of underlying mineral soil. By the 1990s, however, carbon accumulated only in forest biomass, forest floor, and the upper 7.5 cm of mineral soil. Although the forest was a strong carbon sink, trees accounted for about 80%, the forest floor 20%, and mineral soil 〈1%, of the carbon accretion. Despite high carbon inputs to the mineral soil, carbon sequestration was limited by rapid decomposition, facilitated by the coarse soil texture and low-activity clay mineralogy.
    Keywords: Carbon Cycle ; Carbon Budget of Forests ; Carbon in Soil ; Physical Properties/Composition ; 546.26 ; 630.11 ; 631.41;
    ISSN: 0028-0836
    E-ISSN: 1476-4687
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  • 5
    Language: English
    In: BioScience, 1 October 1995, Vol.45(9), pp.600-609
    Description: Biologic processes are studied to prove the claim that soil is much deeper than the depths mentioned in textbooks. These processes involve the spatial and temporal patterns of carbon dioxide in soil atmosphere, carbonic acid in soil solution and soil-exchangeable acidity.
    Keywords: Soil Biology -- Research ; Soil Science -- Research;
    ISSN: 00063568
    E-ISSN: 15253244
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  • 6
    Language: English
    In: Soil Biology and Biochemistry, 2010, Vol.42(2), pp.260-269
    Description: Plant-derived carbon compounds enter soils in a number of forms; two of the most abundant being leaf litter and rhizodeposition. Our knowledge concerning the predominant controls on the cycling of leaf litter far outweighs that for rhizodeposition even though the constituents of rhizodeposits includes a cocktail of low molecular weight organic compounds which represent a rapidly cycling source of carbon, readily available to soil microbes. We determined the mineralization dynamics of a major rhizodeposit, glucose, and its relationship to land-use, microbial community and edaphic characteristics across a landscape in the southeastern United States. The landscape consists of cultivated, pasture, pine plantation, and hardwood forest sites (  = 3). Mineralization dynamics were resolved in both winter and summer using an C-glucose pulse-chase approach. Mineralization rates of the labeled glucose decline exponentially across the 72 h measurement periods. This pattern and absolute mineralization rates are consistent across seasons. An information-theoretic approach reveals that land-use is a moderately strong predictor of cumulative glucose mineralization. Measures assessing the size, activity, and/or composition of the microbial community were poor predictors of glucose mineralization. The strongest predictor of glucose mineralization was soil-extractable phosphorus. It was positively related to glucose mineralization across seasons and explained 60% and 48% of variation in cumulative glucose mineralization in the summer and winter, respectively. We discuss potential mechanisms underlying the relationship between soil phosphorus and glucose mineralization. Our results suggest that specific soil characteristics often related to land-use and/or land-management decisions may be strong predictors of glucose mineralization rates across a landscape. We emphasize the need for future research into the role of soil phosphorus availability and land-use history in determining soil organic carbon dynamics.
    Keywords: Soil Microbial Communities ; Root Exudates ; Low Molecular Weight Compounds ; Fungal-to-Bacterial Ratios ; Land-Use ; Rhizosphere ; Carbon Cycling ; Decomposition ; Agriculture ; Chemistry
    ISSN: 0038-0717
    E-ISSN: 1879-3428
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  • 7
    Language: English
    In: Soil biology & biochemistry, 2010, Vol.42, pp.260-269
    Description: Plant-derived carbon compounds enter soils in a number of forms; two of the most abundant being leaf litter and rhizodeposition. Our knowledge concerning the predominant controls on the cycling of leaf litter far outweighs that for rhizodeposition even though the constituents of rhizodeposits includes a cocktail of low molecular weight organic compounds which represent a rapidly cycling source of carbon, readily available to soil microbes. We determined the mineralization dynamics of a major rhizodeposit, glucose, and its relationship to land-use, microbial community and edaphic characteristics across a landscape in the southeastern United States. The landscape consists of cultivated, pasture, pine plantation, and hardwood forest sites (n = 3). Mineralization dynamics were resolved in both winter and summer using an in situ 13C-glucose pulse-chase approach. Mineralization rates of the labeled glucose decline exponentially across the 72 h measurement periods. This pattern and absolute mineralization rates are consistent across seasons. An information-theoretic approach reveals that land-use is a moderately strong predictor of cumulative glucose mineralization. Measures assessing the size, activity, and/or composition of the microbial community were poor predictors of glucose mineralization. The strongest predictor of glucose mineralization was soil-extractable phosphorus. It was positively related to glucose mineralization across seasons and explained 60% and 48% of variation in cumulative glucose mineralization in the summer and winter, respectively. We discuss potential mechanisms underlying the relationship between soil phosphorus and glucose mineralization. Our results suggest that specific soil characteristics often related to land-use and/or land-management decisions may be strong predictors of glucose mineralization rates across a landscape. We emphasize the need for future research into the role of soil phosphorus availability and land-use history in determining soil organic carbon dynamics. ; Includes references ; p. 260-269.
    Keywords: Soil Organic Carbon ; Seasonal Variation ; Soil Fertility ; Forest Plantations ; Pastures ; Phosphorus ; Agricultural Land ; Isotope Labeling ; Temporal Variation ; Soil Microorganisms ; Edaphic Factors ; Land Management ; Glucose ; Mineralization ; Temperate Forests ; Land Use ; Root Systems
    ISSN: 0038-0717
    Source: AGRIS (Food and Agriculture Organization of the United Nations)
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  • 8
    Lexicon Article
    Lexicon Article
    Language: English
    In: Berkshire Encyclopedia of World History
    ISBN: 978-1-84972-976-5
    Source: Gale Virtual Reference Library (GVRL)
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  • 9
    Language: English
    In: Clays and Clay Minerals, 2018, Vol.66(1), pp.61-73
    Description: Chemical denudation and chemical weathering rates vary under climatic, bedrock, biotic, and topographic conditions. Constraints for landscape evolution models must consider changes in these factors on human and geologic time scales. Changes in nutrient dynamics, related to the storage and exchange of K + in clay minerals as a response to land use change, can affect the rates of chemical weathering and denudation. Incorporation of these changes in landscape evolution models can add insight into how land use changes affect soil thickness and erodibility. In order to assess changes in soil clay mineralogy that result from land-use differences, the present study contrasts the clay mineral assemblages in three proximal sites that were managed differently over nearly the past two centuries where contemporary vegetation was dominated by old hardwood forest, old-field pine, and cultivated biomes. X-ray diffraction (XRD) of the oriented clay fraction using K-, Mg-, and Na-saturation treatments for the air-dried, ethylene glycol (Mg-EG and K-EG) solvated, and heated (100, 350, and 550°C) states were used to characterize the clay mineral assemblages. XRD patterns of degraded biotite (oxidized Fe and expelled charge-compensating interlayer K) exhibited coherent scattering characteristics similar to illite. XRD patterns of the Mg-EG samples were, therefore, accurately modeled using NEWMOD2® software by the use of mineral structure files for discrete illite, vermiculite, kaolinite, mixed-layer kaolinite-smectite, illite-vermiculite, kaolinite-illite, and hydroxy-interlayered vermiculite. The soil and upper saprolite profiles that formed on a Neoproterozoic gneiss in the Calhoun Experimental Forest in South Carolina, USA, revealed a depth-dependence for the deeply weathered kaolinitic to the shallowly weathered illitic/vermiculitic mineral assemblages that varied in the cultivated, pine, and hardwood sites, respectively. An analysis of archived samples that were collected over a five-decade growth period from the pine site suggests that the content of illite-like layers increased at the surface within 8 y. Historical management of the sites has resulted in different states of dynamic equilibrium, whereby deep rooting at the hardwood and pine sites promotes nutrient uplift of K from the weathering of orthoclase and micas. Differences in the denudation rates at the cultivated, pine, and hardwood sites through time were reflected by changes in the soil clay mineralogy. Specifically, an increased abundance of illite-like layers in the surface soils can serve as a reservoir of K + .
    Keywords: Calhoun Experimental Forest ; Degraded Biotite ; Kaolinitic Ultisol ; X-ray Pattern Modeling
    ISSN: 0009-8604
    E-ISSN: 1552-8367
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  • 10
    Language: English
    In: Ecology, October 2008, Vol.89(10), pp.2911-23
    Description: In the ancient and acidic Ultisol soils of the Southern Piedmont, USA, we studied changes in trace element biogeochemistry over four decades, a period during which formerly cultivated cotton fields were planted with pine seedlings that grew into mature forest stands. In 16 permanent plots, we estimated 40-year accumulations of trace elements in forest biomass and O horizons (between 1957 and 1997), and changes in bioavailable soil fractions indexed by extractions of 0.05 mol/L HCl and 0.2 mol/L acid ammonium oxalate (AAO). Element accumulations in 40-year tree biomass plus O horizons totaled 0.9, 2.9, 4.8, 49.6, and 501.3 kg/ha for Cu, B, Zn, Mn, and Fe, respectively. In response to this forest development, samples of the upper 0.6-m of mineral soil archived in 1962 and 1997 followed one of three patterns. (1) Extractable B and Mn were significantly depleted, by -4.1 and -57.7 kg/ha with AAO, depletions comparable to accumulations in biomass plus O horizons, 2.9 and 49.6 kg/ha, respectively. Tree uptake of B and Mn from mineral soil greatly outpaced resupplies from atmospheric deposition, mineral weathering, and deep-root uptake. (2) Extractable Zn and Cu changed little during forest growth, indicating that nutrient resupplies kept pace with accumulations by the aggrading forest. (3) Oxalate-extractable Fe increased substantially during forest growth, by 275.8 kg/ha, about 10-fold more than accumulations in tree biomass (28.7 kg/ha). The large increases in AAO-extractable Fe in surficial 0.35-m mineral soils were accompanied by substantial accretions of Fe in the forest's O horizon, by 473 kg/ha, amounts that dwarfed inputs via litterfall and canopy throughfall, indicating that forest Fe cycling is qualitatively different from that of other macro- and micronutrients. Bioturbation of surficial forest soil layers cannot account for these fractions and transformations of Fe, and we hypothesize that the secondary forest's large inputs of organic additions over four decades has fundamentally altered soil Fe oxides, potentially altering the bioavailability and retention of macro- and micronutrients, contaminants, and organic matter itself. The wide range of responses among the ecosystem's trace elements illustrates the great dynamics of the soil system over time scales of decades.
    Keywords: Biomass ; Soil -- Analysis ; Trace Elements -- Analysis ; Trees -- Metabolism
    ISSN: 0012-9658
    E-ISSN: 19399170
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