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Berlin Brandenburg

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  • 1
    In: Nature, 2016, Vol.536(7617), p.E1
    Description: In their study, Evaristo et al.1 collected an extensive data set on the basis of which they statistically determined the isotopic compositions of the plant water source (δ 18Ointersect and δ 2Hintersect, called respectively δ 18Ointercept and δ 2Hintercept in their paper) as the x and y coordinates in (δ 18O, δ 2H) space of the intersection between the local meteoric water line (LMWL) and the plant xylem water 'evaporation line' (EL) for a range of climates and vegetation types.
    Keywords: Isotopes ; Groundwater ; Groundwater Recharge ; Stream Flow ; Precipitation ; Botany ; Flowers & Plants;
    ISSN: 0028-0836
    E-ISSN: 1476-4687
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  • 2
    In: Global Change Biology, March 2017, Vol.23(3), pp.1338-1352
    Description: Salinity intrusion caused by land subsidence resulting from increasing groundwater abstraction, decreasing river sediment loads and increasing sea level because of climate change has caused widespread soil salinization in coastal ecosystems. Soil salinization may greatly alter nitrogen (N) cycling in coastal ecosystems. However, a comprehensive understanding of the effects of soil salinization on ecosystem N pools, cycling processes and fluxes is not available for coastal ecosystems. Therefore, we compiled data from 551 observations from 21 peer‐reviewed papers and conducted a meta‐analysis of experimental soil salinization effects on 19 variables related to N pools, cycling processes and fluxes in coastal ecosystems. Our results showed that the effects of soil salinization varied across different ecosystem types and salinity levels. Soil salinization increased plant N content (18%), soil (12%) and soil total N (210%), although it decreased soil (2%) and soil microbial biomass N (74%). Increasing soil salinity stimulated soil NO fluxes as well as hydrological and fluxes more than threefold, although it decreased the hydrological dissolved organic nitrogen () flux (59%). Soil salinization also increased the net N mineralization by 70%, although salinization effects were not observed on the net nitrification, denitrification and dissimilatory nitrate reduction to ammonium in this meta‐analysis. Overall, this meta‐analysis improves our understanding of the responses of ecosystem N cycling to soil salinization, identifies knowledge gaps and highlights the urgent need for studies on the effects of soil salinization on coastal agro‐ecosystem and microbial N immobilization. Additional increases in knowledge are critical for designing sustainable adaptation measures to the predicted intrusion of salinity intrusion so that the productivity of coastal agro‐ecosystems can be maintained or improved and the N losses and pollution of the natural environment can be minimized.
    Keywords: Costal Ecosystem ; Denitrification ; Dissimilatory Nitrate Reduction To Ammonium Dnra ; Nitrogen Cycle ; Salinity Intrusion ; Sea‐Level Rise ; Soil Salinization
    ISSN: 1354-1013
    E-ISSN: 1365-2486
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  • 3
    Language: English
    In: Soil Biology and Biochemistry, May 2015, Vol.84, pp.107-115
    Description: Despite the fact that microbial nitrification and denitrification are considered the major soil N O emission sources, especially from agricultural soils, several abiotic reactions involving the nitrification intermediate hydroxylamine (NH OH) have been identified leading to N O emissions, but are being neglected in most current studies. Here, we studied N O formation from NH OH in cropland, grassland, and forest soils in laboratory incubation experiments. Incubations were conducted with and without the addition of NH OH to non-sterile and sterile soil samples. N O evolution was quantified with gas chromatography and further analyzed with online laser absorption spectroscopy. Additionally, the isotopic signature of the produced N O (δ N, δ O, and N site preference) was analyzed with isotope ratio mass spectrometry. While the forest soil samples showed hardly any N O evolution upon the addition of NH OH, immediate and very large formation of N O was observed in the cropland soil, also in sterilized samples. Correlation analysis revealed soil parameters that might explain the variability of NH OH-induced N O production to be: soil pH, C/N ratio, and Mn content. Our results suggest a coupled biotic–abiotic production of N O during nitrification, e.g. due to leakage of the nitrification intermediate NH OH with subsequent reaction with the soil matrix.
    Keywords: Coupled Biotic–Abiotic Process ; Nitrification ; Intermediate ; N2o ; Nh2oh ; Agriculture ; Chemistry
    ISSN: 0038-0717
    E-ISSN: 1879-3428
    Source: ScienceDirect Journals (Elsevier)
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  • 4
    Language: English
    In: Soil Biology and Biochemistry, December 2017, Vol.115, pp.261-264
    Description: Open-cast lignite mining consumes arable land, which has to be restored and recultivated afterwards. This process strongly dilutes the organic carbon and nitrogen pool as well as soil biological parameters of the former soil due to mixing with the underlying subsoil and parent material before redeposition. Cultivation of alfalfa is commonly used to restore agricultural land and to refill diluted C and N pools and re-establish biologic functions. Based on nematode-derived indices, we here evaluate the development of the food web during the early recovery period with N-fixing alfalfa on post-mining soil substrates in the lignite mining district west of Cologne (Germany). Nematode-derived indices revealed a fast recovery of the soil food web during this initial alfalfa cultivation. We found evidence that the applied recultivation procedure lowers the stress and disturbance level in the soil-microbial food web and improves the trophic complexity. The fast maturing of the food web was indicated by nematodes, which indicated a highly structured and stable food web already after three years of alfalfa cultivation. A declining δ N signal of the soil indicated a strong impact of N-fixation by alfalfa. Microbial and mineral N content increased during the alfalfa cultivation period. We concluded that the rapid recovery of the soil food web might not be paralleled by an equal increase of its capacity to retain N in the soil food web. This might have implications for nitrate leaching, nitrous oxide emission, and a later agricultural recultivation with common field crops.
    Keywords: Brown Coal ; Nitrous Oxide ; Soil Restoration ; Agriculture ; Chemistry
    ISSN: 0038-0717
    E-ISSN: 1879-3428
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  • 5
    In: Nature, 2010, Vol.464(7290), p.881
    Description: Atmospheric concentrations of the greenhouse gas nitrous oxide ([N.sub.2]O) have increased significantly since pre-industrial times owing to anthropogenic perturbation of the global nitrogen cycle (1,2), with animal production being one of the main contributors (3). Grasslands cover about 20 per cent of the temperate land surface of the Earth and are widely used as pasture. It has been suggested that high animal stocking rates and the resulting elevated nitrogen input increase [N.sub.2]O emissions (4-7). Internationally agreed methods to upscale the effect of increased livestock numbers on [N.sub.2]O emissions are based directly on per capita nitrogen inputs (8). However, measurements of grassland [N.sub.2]O fluxes are often performed over short time periods (9), with low time resolution and mostly during the growing season. In consequence, our understanding of the daily and seasonal dynamics of grassland [N.sub.2]O fluxes remains limited. Here we report year-round [N.sub.2]O flux measurements with high and low temporal resolution at ten steppe grassland sites in Inner Mongolia, China. We show that short-lived pulses of [N.sub.2]O emission during spring thaw dominate the annual [N.sub.2]O budget at our study sites. The [N.sub.2]O emission pulses are highest in ungrazed steppe and decrease with increasing stocking rate, suggesting that grazing decreases rather than increases [N.sub.2]O emissions. Our results show that the stimulatory effect of higher stocking rates on nitrogen cycling (4,7) and, hence, on [N.sub.2]O emission is more than offset by the effects of a parallel reduction in microbial biomass, inorganic nitrogen production and wintertime water retention. By neglecting these freeze-thaw interactions, existing approaches may have systematically overestimated [N.sub.2]O emissions over the last century for semi-arid, cool temperate grasslands by up to 72 per cent.
    Keywords: Biogeochemical Cycles -- Observations ; Nitrous Oxide -- Environmental Aspects ; Atmospheric Carbon Dioxide -- Properties ; Grasslands -- Natural History ; Greenhouse Gases -- Properties ; Livestock Industry -- Environmental Aspects ; Air Pollution Research -- Methods;
    ISSN: 0028-0836
    E-ISSN: 14764687
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  • 6
    In: Global Change Biology, October 2017, Vol.23(10), pp.4068-4083
    Description: Animal manure application as organic fertilizer does not only sustain agricultural productivity and increase soil organic carbon () stocks, but also affects soil nitrogen cycling and nitrous oxide (NO) emissions. However, given that the sign and magnitude of manure effects on soil NO emissions is uncertain, the net climatic impact of manure application in arable land is unknown. Here, we performed a global meta‐analysis using field experimental data published in peer‐reviewed journals prior to December 2015. In this meta‐analysis, we quantified the responses of NO emissions to manure application relative to synthetic N fertilizer application from individual studies and analyzed manure characteristics, experimental duration, climate, and soil properties as explanatory factors. Manure application significantly increased NO emissions by an average 32.7% (95% confidence interval: 5.1–58.2%) compared to application of synthetic N fertilizer alone. The significant stimulation of NO emissions occurred following cattle and poultry manure applications, subsurface manure application, and raw manure application. Furthermore, the significant stimulatory effects on NO emissions were also observed for warm temperate climate, acid soils ( 〈 6.5), and soil texture classes of sandy loam and clay loam. Average direct NO emission factors (s) of 1.87% and 0.24% were estimated for upland soils and rice paddy soils receiving manure application, respectively. Although manure application increased stocks, our study suggested that the benefit of increasing stocks as sinks could be largely offset by stimulation of soil NO emissions and aggravated by emissions if, particularly for rice paddy soils, the stimulation of emissions by manure application was taken into account. The uncertain manure effects on NO emissions constrain evaluation of the net climatic impact of manure application in arable lands. A global meta‐analysis was performed to quantify the overall responses of NO emissions to manure application relative to synthetic N fertilizer in agricultural soils. Manure application on average significantly increased NO emissions by 32.7% as compared to synthetic N fertilizer alone, and the sign and magnitude of NO emissions were dependent on manure characteristics, climate, and soil properties. The benefit of C sequestration could be largely offset by stimulation of soil NO emissions and aggravated by CH emissions if, particularly for rice paddy soils, the stimulation of CH emissions by manure application was taken into account.
    Keywords: Animal Manure ; Emission Factor ; Greenhouse Gas Balance ; Manure Characteristics ; Meta‐Analysis ; Nitrous Oxide ; Soil Ph ; Soil Texture
    ISSN: 1354-1013
    E-ISSN: 1365-2486
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  • 7
    Language: English
    In: Geochimica et Cosmochimica Acta, 15 August 2014, Vol.139, pp.72-82
    Description: Efficient nitrous oxide (N O) mitigation strategies require the identification of the main source and sink processes and their contribution to total soil N O production. Several abiotic reactions of nitrification intermediates leading to N O production are known, but their contribution to total N O production in soils is uncertain. As the site preference (SP) of N in N O is a promising tool to give more insight into N O production processes, we investigated the SP of N O produced by different abiotic reactions in a laboratory study. All reactions involved the nitrification intermediate hydroxylamine (NH OH) in combination with nitrite (NO ), Fe , Fe and Cu , reactants commonly or potentially found in soils, at different concentrations and pH values. N O production and its four main isotopic species ( N N O, N N O, N N O, and N N O) were quantified simultaneously and online at high temporal resolution using quantum cascade laser absorption spectroscopy. Thereby, our study presents the first continuous analysis of δ O in N O. The experiments revealed the possibility of purely abiotic reactions over a wide range of acidity (pH 3–8) by different mechanisms. All studied abiotic pathways produced N O with a characteristic SP in the range of 34–35‰, unaffected by process conditions and remaining constant over the course of the experiments. These findings reflect the benefit of continuous N O isotopic analysis by laser spectroscopy, contribute new information to the challenging source partitioning of N O emissions from soils, and emphasize the potentially significant role of coupled biotic–abiotic reactions in soils.
    Keywords: Geology
    ISSN: 0016-7037
    E-ISSN: 1872-9533
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  • 8
    Language: English
    In: Soil Biology and Biochemistry, October 2017, Vol.113, pp.153-160
    Description: Emissions of gaseous forms of nitrogen from soil, such as nitrous oxide (N O) and nitric oxide (NO), have shown great impact on global warming and atmospheric chemistry. Although in soil both nitrification and denitrification could cause N O and NO emissions, most studies demonstrated that denitrification is the dominant process responsible for the increase of atmospheric N O, while nitrification produces mostly NO. The use of nitrification inhibitors (NIs) has repeatedly been shown to reduce both N O and NO emissions from agricultural soils; nevertheless, the efficiency of the mitigation effect varies greatly. It is generally assumed that nitrification inhibitors have no direct effect on denitrification. However, the indirect impact, due to the reduced substrate (nitrate) delivery to microsites where denitrification occurs, may have significant effects on denitrification product stoichiometry that may significantly lower soil-borne N O emissions. Soil-water status is considered to have a remarkable effect on the relative fluxes of nitrogen gases. The effect and mechanism of NI on N O, NO and N emission under different soil water-filled pore space (WFPS) is still not well explored. In the present study, we conducted a soil incubation experiment in an automated continuous-flow incubation system under a He/O atmosphere. Ammonium sulfate was applied with and without NI (DMPP) to a permanent UK grassland soil under three different soil moisture conditions (50, 65, and 80% WFPS). With every treatment, glucose was applied to supply enough available carbon for denitrification. Emissions of CO , N O, NO and N were investigated. Additionally, isotopic signatures of soil-emitted N O were analyzed. Generally, higher WFPS led to higher N O and NO emissions, while N emissions were only detected at high soil moisture condition (80% WFPS). Different processes were responsible for N O and NO emission in different phases of the incubation period. The application of DMPP did significantly reduce both N O and NO emissions at all three soil moisture conditions. Furthermore, DMPP application increased N emissions and decreased the N O/(N O + N ) product ratio at 80% WFPS.
    Keywords: Nitrification Inhibitor ; Denitrification ; Nitrous Oxide ; Nitric Oxide ; Dinitrogen ; Isotopomer ; Agriculture ; Chemistry
    ISSN: 0038-0717
    E-ISSN: 1879-3428
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  • 9
    Language: English
    In: Soil Biology and Biochemistry, June 2018, Vol.121, pp.147-153
    Description: The winter wheat–summer maize rotation system in the North China Plain is a major source of nitrous oxide (N O) emissions due to high nitrogen (N) fertilizer and irrigation water inputs. However, a detailed understanding of the contribution of N O production sources is still limited because of the complexity of N O generation in soils and a lack of relevant field studies. Moreover, the efficiency and mechanisms of N O mitigation approaches in this area, i.e. the use of nitrification inhibitors, remains poorly understood. To elucidate the N O production pathways from this rotation system and to evaluate the effect of a widely used nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) on mitigating N O emissions, we monitored N O fluxes and analyzed isotopomer ratios of soil-emitted N O during one rotation year. Results indicate that the application of DMPP significantly reduced N O emissions by 67% in the winter wheat season and 47% in the summer maize season. Isotopomer analysis revealed that in the N-fertilized treatment, nitrification and/or fungal denitrification accounted for up to 36% of the N O emission peaks observed after fertilization and irrigation events, whereas the nitrifier denitrification pathway was likely to be the major source, accounting for the remaining N O emissions. The high effectiveness of the nitrification inhibitor on mitigating N O emissions at high soil moisture may be attributed to the dual inhibitory effect on nitrifier denitrification, i.e. reducing the supply of nitrite, which is the substrate of nitrifier denitrification and inhibiting ammonia-oxidizing bacteria activities, which carry nitrifier denitrification.
    Keywords: Nitrous Oxide ; Isotopomer ; Nitrification Inhibitor ; Nitrifier Denitrification ; Agriculture ; Chemistry
    ISSN: 0038-0717
    E-ISSN: 1879-3428
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  • 10
    Language: English
    In: Soil Biology and Biochemistry, February 2014, Vol.69, pp.168-178
    Description: The stabilization of soil organic matter (SOM) is triggered by three main mechanisms: (i) low bioavailability due to aggregation, (ii) recalcitrance due to the chemical structure, and (iii) association of the SOM with mineral surfaces. In the present study we used particle size SOM fractions (sand, silt and clay), derived from the Ah soil horizon from a Norway spruce forest in Southern Germany, to study the effects of different stabilization mechanisms on the bioavailability of soil organic carbon (SOC) in a one year incubation experiment. The respired CO was hourly recorded, additionally CO was analysed 20 times and CO three times during the incubation experiment. To better differentiate between particulate OM (POM) and mineral associated OM (MIN), the incubated fractions and bulk soil were separated according to density (1.8 g cm ) after the incubation experiment. C-CPMAS NMR spectroscopy was used to study the chemical composition of the incubated samples. We demonstrate a clear increase in SOM bioavailability due to aggregate disruption, as the calculated theoretical CO evolution of the SOM fractions recombined by calculation was 43.8% higher in relation to the intact bulk soil. The incubated sand fraction, dominated by POM rich in O/N-alkyl C, showed a prolonged bioavailability of SOC moieties with mean residence times (MRT) of 78 years. Interestingly, the silt fraction, dominated by highly aliphatic, more recalcitrant POM, showed low mineralization rates and slow MRT's (192 years) close to values for the clay fraction (171 years), which contained a large amount of mineral-associated SOM. The recorded CO signatures showed a high depletion in C during the initial stage of the incubation, but an enrichment of the respired CO of up to 3.4‰ relative to the incubated SOM was observed over longer time periods (after 3 and 4 days for bulk soil and sand, respectively, and after 14 days for silt and clay). Therefore, we found no evidence for a C enrichment of SOM as driven by metabolic isotopic fractionation during microbial SOM mineralization, but an indication of a change in the isotopic composition of the C-source over time.
    Keywords: 13co2 ; 14co2 ; Laboratory Incubation ; Heterotrophic Respiration ; 13c-Cpmas NMR Spectroscopy ; Particle Size Fractionation ; Density Fractionation ; Mean Residence Time ; Microbial Biomass ; Agriculture ; Chemistry
    ISSN: 0038-0717
    E-ISSN: 1879-3428
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