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31.
H. Vervaet P. Boeckx V. Unamuno O. Van Cleemput G. Hofman 《Biology and Fertility of Soils》2002,36(2):143-150
This paper studies changes of 15N signatures ('15N, ) and total N (TN, %) in soil profiles among forest stands with different NO3- {\rm NO}_3^ - losses within the same climatic zone. An additional aim was to investigate whether the change of '15N (('15N) within the 0-10, 10-20 and 20-30 cm depths of the mineral layer could be linked to measured potential net N mineralization rates. Soil samples were collected from five forest stands in Belgium: three mixed deciduous forests (G, AE, LD), a homogenous deciduous (SB) and a coniferous stand (CP). At the G site, five locations were sampled: one at the forest edge (GE), two deeper in the forest (GF1, GF2), one clear-cut spot (GO) and one in coppice wood (GC). The '15N and TN measurements were conducted for the litter layer, the fermentation + humus layer and the underlying mineral layers (0-30 cm, at 2 cm intervals). The '15N values increased with depth, ranging from -12 to -1 for the forest floor and from -7 to +15 for the mineral layers. The overall enrichment factor was greater for locations GE, AE and SB (-5.2, P <0.001, R2 =0.86) than locations GF1, GF2, GO, GC, LD and CP (-2.4, P <0.001, R2 =0.93), possibly indicating NO3- losses. A significant linear regression model could be calculated between ('15N and potential net N mineralization rates (y =0.04x), explaining 65% of the variability of ('15N. Thus, '15N profiles in forest soils might be useful as an indicator of NO3- {\rm NO}_3^ - loss and N mineralization behaviour, however, further research is needed to confirm our observations. 相似文献
32.
Sediment source fingerprinting: benchmarking recent outputs,remaining challenges and emerging themes
Collins Adrian L. Blackwell Martin Boeckx Pascal Chivers Charlotte-Anne Emelko Monica Evrard Olivier Foster Ian Gellis Allen Gholami Hamid Granger Steve Harris Paul Horowitz Arthur J. Laceby J. Patrick Martinez-Carreras Nuria Minella Jean Mol Lisa Nosrati Kazem Pulley Simon Silins Uldis da Silva Yuri Jacques Stone Micheal Tiecher Tales Upadhayay Hari Ram Zhang Yusheng 《Journal of Soils and Sediments》2020,20(12):4160-4193
Journal of Soils and Sediments - This review of sediment source fingerprinting assesses the current state-of-the-art, remaining challenges and emerging themes. It combines inputs from international... 相似文献
33.
Soil properties influencing the denitrification potential of Flemish agricultural soils 总被引:3,自引:0,他引:3
D'Haene Karoline Moreels Edwin De Neve Stefaan Chaves Daguilar Barbara Boeckx Pascal Hofman Georges Van Cleemput Oswald 《Biology and Fertility of Soils》2003,38(6):358-366
The denitrification potential of the soil horizons between 0- and 90-cm depth of 20 agricultural fields, representative of the most frequent combinations of agricultural crops and soil textures in Flanders (Belgium), and the factors affecting the denitrification potential were studied in the laboratory under controlled conditions. The denitrification potential in the presence of an added soluble C and N source was measured at 15°C after saturation of air-dried soil samples with water. The denitrification potential of the lower horizons was generally negligible compared to the upper horizons. The lower denitrification potential of the deeper horizons could partially be explained by their limited C availability. The denitrification potential of the upper horizons strongly depended on texture. Based on this parameter the soils could be divided into three groups: soils with a high clay content (>30% clay) were characterised by a high denitrification potential (>8.33 µg N g-1 dry soil day-1); soils with medium texture had a medium denitrification potential, between 0.41 and 7.25 µg N g-1 dry soil day-1; and soils with a high sand content (>80% sand) had a low denitrification potential (<2.58 µg N g-1 dry soil day-1). In most cases, extending the saturation period during pre-incubation increased the denitrification potential. Comparison of the denitrification potential of the upper horizons with and without addition of a soluble C source showed that the denitrification potential of the upper horizons of these soils was limited by their percentage of endogenous C. The measured denitrification potentials indicate that denitrification losses in soils high in clay content can be important when NO3
- concentrations are high. 相似文献
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35.
Karolien Denef Mihiri C.W. Manimel Wadu Pascal Boeckx 《Soil biology & biochemistry》2009,41(1):144-153
Rhizodeposit-carbon provides a major energy source for microbial growth in the rhizosphere of grassland soils. However, little is known about the microbial communities that mediate the rhizosphere carbon dynamics, especially how their activity is influenced by changes in soil management. We combined a 13CO2 pulse-labeling experiment with phospholipid fatty acid (PLFA) analysis in differently managed Belgian grasslands to identify the active rhizodeposit-C assimilating microbial communities in these grasslands and to evaluate their response to management practices. Experimental treatments consisted of three mineral N fertilization levels (0, 225 and 450 kg N ha−1 y−1) and two mowing frequencies (3 and 5 times y−1). Phospholipid fatty acids were extracted from surface (0-5 cm) bulk (BU) and root-adhering (RA) soil samples prior to and 24 h after pulse-labeling and were analyzed by gas chromatography-combustion-isotope ratio mass spectrometry (GC-c-IRMS). Soil habitats significantly differed in microbial community structure (as revealed by multivariate analysis of mol% biomarker PLFAs) as well as in gram-positive bacterial rhizodeposit-C uptake (as revealed by greater 13C-PLFA enrichment following pulse-labeling in RA compared to BU soil in the 450N/5M treatment). Mowing frequency did not significantly alter the relative abundance (mol%) or activity (13C enrichment) of microbial communities. In the non-fertilized treatment, the greatest 13C enrichment was seen in all fungal biomarker PLFAs (C16:1ω5, C18:1ω9, C18:2ω6,9 and C18:3ω3,6,9), which demonstrates a prominent contribution of fungi in the processing of new photosynthate-C in non-fertilized grassland soils. In all treatments, the lowest 13C enrichment was found in gram-positive bacterial and actinomycetes biomarker PLFAs. Fungal biomarker PLFAs had significantly lower 13C enrichment in the fertilized compared to non-fertilized treatments in BU soil (C16:1ω5, C18:1ω9) as well as RA soil (all fungal biomarkers). While these observations clearly indicated a negative effect of N fertilization on fungal assimilation of plant-derived C, the effect of N fertilization on fungal abundance could only be detected for the arbuscular mycorrhizal fungal (AMF) PLFA (C16:1ω5). On the other hand, increases in the relative abundance of gram-positive bacterial PLFAs with N fertilization were found without concomitant increases in 13C enrichment following pulse-labeling. We conclude that in situ13C pulse-labeling of PLFAs is an effective tool to detect functional changes of those microbial communities that are dominantly involved in the immediate processing of new rhizosphere-C. 相似文献
36.
Svetlana Bykova Pascal Boeckx Irina Kravchenko Valery Galchenko Oswald Van Cleemput 《Biology and Fertility of Soils》2007,43(3):341-348
Methane oxidising activity and community structure of 11, specifically targeted, methanotrophic species have been examined
in an arable soil. Soils were sampled from three different field plots, receiving no fertilisation (C), compost (G) and mineral
fertiliser (M), respectively. Incubation experiments were carried out with and without pre-incubation at elevated CH4 mixing ratios (100 ml CH4 l−1) and with and without ammonium (100 mg N kg−1) pre-incubation. Four months after fertilisation, plots C, G and M did not show significant differences in physicochemical
properties and CH4 oxidising activity. The total number of methanotrophs (determined as the sum the 11 specifically targeted methanotrophs)
in the fresh soils was 17.0×106, 13.7×106 and 15.5×106 cells g−1 for treatment C, G and M, respectively. This corresponded to 0.11 to 0.32% of the total bacterial number. The CH4 oxidising activity increased 105-fold (20–26 mg CH4 g−1 h−1), the total number of methanotrophs doubled (28–76×106 cells g−1) and the methanotrophic diversity markedly increased in treatments with a pre-incubation at elevated CH4 concentrations. In all soils and treatments, type II methanotrophs (62–91%) outnumbered type I methanotrophs (9–38%). Methylocystis and Methylosinus species were always most abundant. After pre-incubation with ammonium, CH4 oxidation was completely inhibited; however, no change in the methanotrophic community structure could be detected. 相似文献