Fumigation-Extraction

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Ross A Virginia - One of the best experts on this subject based on the ideXlab platform.

Rainer Georg Joergensen - One of the best experts on this subject based on the ideXlab platform.

  • microbial biomass phosphorus and c n p stoichiometry in forest floor and a horizons as affected by tree species
    Soil Biology & Biochemistry, 2017
    Co-Authors: Ulrike Talkner, Dan Paul Zederer, Marie Spohn, Rainer Georg Joergensen
    Abstract:

    Abstract Forest floor horizons contain significant total P stocks, but information on the contribution of microbial biomass P (PMB) and on the controlling factors of this pool is limited. Slightly modified fumigation extraction procedures were used to investigate the stoichiometric relationships of PMB to microbial biomass C (CMB) and microbial biomass N (NMB) in the forest floor (L, F, H, and A horizons) at five sites, differing in P availability to trees, under adjacent spruce (Picea abies) and beech (Fagus sylvatica) stands. CMB, NMB, and PMB contents were higher in forest floors under beech than under spruce. Mean stocks of PMB and total P were roughly 27 and 100 kg ha−1 in the forest floor, respectively, but did not differ between the tree species, due to an increased organic matter accumulation in the forest floor under spruce. This reveals the importance of forest floor horizons and microbial biomass turnover for P nutrition of trees in acidic soils with the humus form moder. C/PMB ratios declined from roughly 26 in L to 13 in F and H horizons, followed by an increase to roughly 17 in A horizons. The range of C/PMB ratios was small at all sites in relation to the wide SOC/total P ratios of the litter used as microbial substrate, indicating a relatively strict homeostatic regulation of the forest floor microbial, mainly fungal biomass stoichiometry.

  • simultaneous measurement of s macronutrients and heavy metals in the soil microbial biomass with chcl3 fumigation and nh4no3 extraction
    Soil Biology & Biochemistry, 2009
    Co-Authors: Khalid Saifullah Khan, Stefanie Heinze, Rainer Georg Joergensen
    Abstract:

    Abstract The study was carried out to investigate whether 1 M NH 4 NO 3 extraction is a useful alternative to 10 mM CaCl 2 extraction for estimating soil microbial biomass S and whether the data of CHCl 3 -labile NH 4 NO 3 -extractable macronutrients and heavy metals are useful and in agreement with the available data on element concentrations in soil microorganisms. Microbial biomass C was followed by microbial biomass S after CaCl 2 extraction with an average C/S ratio of 82, and by microbial biomass S after NH 4 NO 3 extraction with an average C/S ratio of 57. The mean contribution of CHCl 3 -labile metals in relation to the NH 4 NO 3 -extractable fraction from non-fumigated soils ranged from 0.1 to 112% in the order potassium  3 -labile metals in relation to the microbial biomass C ranged from 0.03 to 22‰ in the order cadmium  + ) to a more than 200-fold range (Cu 2+ ). Significant positive correlations with microbial biomass C were observed for CHCl 3 -labile zinc, sodium and especially potassium. The concentration of all elements except copper in relation to microbial biomass C were in the range known from the limited literature on fungi grown on heavy metal contaminated soils.

  • soil microbial community composition as affected by restoration practices in california grassland
    Soil Biology & Biochemistry, 2006
    Co-Authors: Martin Potthoff, Kate M Scow, Kerri L Steenwerth, Louise E Jackson, Rebecca E Drenovsky, Rainer Georg Joergensen
    Abstract:

    Abstract Agricultural practices have strong impacts on soil microbes including both the indices related to biomass and activity as well as those related to community composition. In a grassland restoration project in California, where native perennial bunchgrasses were introduced into non-native annual grassland after a period of intensive tillage, weeding, and herbicide use to reduce the annual seed bank, microbial community composition was investigated. Three treatments were compared: annual grassland, bare soil fallow, and restored perennial grassland. Soil profiles down to 80 cm in depth were investigated in four separate layers (0–15, 15–30, 30–60, and 60–80 cm) using both phospholipid ester-linked fatty acid (PLFAs) and ergosterol as biomarkers in addition to microbial biomass C by fumigation extraction. PLFA fingerprinting showed much stronger differences between the tilled bare fallow treatment vs. grasslands, compared to fewer differences between restored perennial grassland and annual grassland. The presence or absence of plants over several years clearly distinguished microbial communities. Microbial communities in lower soil layers were little affected by management practices. Regardless of treatment, soil depth caused a strong gradient of changing habitat conditions, which was reflected in Canonical Correspondence Analysis of PLFAs. Fungal organisms were associated with the presence of plants and/or litter since the total amount and the relative proportion of fungal markers were reduced in the tilled bare fallow and in lower layers of the grassland treatments. Total PLFA and soil microbial biomass were highly correlated, and fungal PLFA biomarkers showed strong correlations to ergosterol content. In conclusion, microbial communities are resilient to the grassland restoration process, but do not reflect the change in plant species composition that occurred after planting native bunchgrasses.

  • the determination of δ13c in soil microbial biomass using fumigation extraction
    Soil Biology & Biochemistry, 2003
    Co-Authors: Martin Potthoff, Rainer Georg Joergensen, Norman Loftfield, Franz Buegger, Barbara Wick, Bettina John, Heiner Flessa
    Abstract:

    Abstract The determination of the isotopic composition of the microbial biomass C in soil is an important tool to study soil microbial ecology and the decomposition and microbial immobilization of soil organic C. We discuss advantages and disadvantages of different methods to determine 13C/12C in soil microbial biomass and propose a new procedure that is based on the UV-catalyzed liquid oxidation of fumigated and non-fumigated soil extracts combined with trapping of the released CO2 in liquid nitrogen and subsequent determination of δ 13 CO 2 -C by a gas chromatograph connected with an isotope ratio mass spectrometer (IRMS). This method was evaluated using test solutions with known isotopic composition and soil extracts. Additionally, the method was compared with an off-line sample preparation technique combined with isotope analysis by a dual-inlet IRMS and an on-line analysis using an elemental analyser connected with an IRMS. All methods applied obtained comparable results and there were no significant differences between the δ 13 C values measured. The off-line preparation procedure had the highest precision but it was also the most labour-intensive. The choice of the most suitable method depends mainly on the number of samples that have to be analysed, the salt concentration of the extracts and the differences of δ 13 C that have to be detected. The application of this method with liquid oxidation and subsequent GC-IRMS analysis showed that microbial biomass C of a grassland soil was 13C-enriched by 2‰ δ 13 C PDB compared with the total soil organic C. The addition of maize straw resulted in a rapid immobilization of maize C in the microbial biomass.

  • the fumigation extraction method to estimate soil microbial biomass calibration of the kec value
    Soil Biology & Biochemistry, 1996
    Co-Authors: Rainer Georg Joergensen
    Abstract:

    Abstract The kEC value (=extractable part of microbial biomass C) of the Fumigation-Extraction (FE) method was assessed on the basis of 153 soils (94 arable, 46 grassland and 13 forest soils) by indirect calibration using the fumigation-incubation (FI) method. Sixty-six soils were investigated for the first time and the data on a further 87 soils were obtained from the literature. The single kEC values ranged from 0.23 to 0.84. A split according to the form of land use resulted in a significantly (Scheffe, P = 0.05) lower kEC value for the arable soils (0.42; n = 94) in comparison to those for the grassland (0.49; n = 46) and the forest soils (0.51; n = 13). This difference is mainly due to the significant effects of the respiration rate measured in non-fumigated control samples of the FI method which was used for calibration of the kEC value. For that reason, I investigated the effects of incubation temperature (22°, 25° and 28°C) on biomass C data obtained by the FI method, and thus on the kEC value of the FE method, and discuss further problems of direct and indirect calibration. Based on experimental and literature data, I conclude that the kEC values of Vance et al. (Soil Biology & Biochemistry19, 703–707, 1987) and Wu et al. (Soil Biology & Biochemistry22, 1167–1169, 1990) remain valid. A kEC value of 0.38 can be recommended for C analysis by dichromate consumption and a kEC value of 0.45 for that by UV-persulfate or oven oxidation.

Weixin Cheng - One of the best experts on this subject based on the ideXlab platform.

P C Brookes - One of the best experts on this subject based on the ideXlab platform.

  • extraction of soil nitrogen by chloroform fumigation a new index for the evaluation of soil nitrogen supply
    Soil Biology & Biochemistry, 2011
    Co-Authors: P C Brookes, Hua Zhou, Shanmin Shen
    Abstract:

    Abstract The N extracted after chloroform (CHCl 3 ) fumigation was determined as a possible index of soil N supply to plants. The relationships between extractable N following fumigation and reference indices such as total N, alkali-hydrolyzable N, N released by the Stanford short-term incubation method, and the N extracted by KCl and by CaCl 2 , were measured in nine soils of differing soil N supply capacity. A highly significant correlation was achieved between the extractable N released by fumigation and the N released by the Stanford method, i.e. a short-term aerobic incubation ( r  = 0.87). Similarly, the correlation between extractable N by fumigation and the N uptake by ryegrass was highly statistically significant ( r  = 0.93). Using the N extracted following fumigation has the advantage that laboratory results are available in two days and are both reproducible and of high precision. Therefore, the N extracted following fumigation is a valid, timesaving and precise index of soil N supply capacity.

  • impact of black carbon addition to soil on the determination of soil microbial biomass by fumigation extraction
    Soil Biology & Biochemistry, 2010
    Co-Authors: Mark Durenkamp, Yangchao Luo, P C Brookes
    Abstract:

    Abstract The efficiency of the fumigation extraction method on the determination of soil microbial biomass carbon and ninhydrin-N was tested in three different soils (UK grassland, UK arable, Chinese arable) amended with black carbon (biochar or activated charcoal). Addition of activated charcoal to soil resulted in a significant decrease in K 2 SO 4 extractable carbon and ninhydrin-N in all three soils, whereas the addition of biochar generally did not. A lower concentration of the extraction reagent (0.05 M vs. 0.5 M K 2 SO 4 ) resulted in a significantly lower extraction efficiency in the grassland soil. The extraction efficiency of organic carbon was more affected by black carbon than that of ninhydrin-N, which resulted in a decreased biomass C/ninhydrin-N ratio. The impact of black carbon on the extraction efficiency of soil microbial biomass depended on the type of black carbon, on the concentration of the extraction medium and on soil type.

  • evaluating soil microbial biomass carbon as an indicator of long term environmental change
    Soil Biology & Biochemistry, 2003
    Co-Authors: P R Hargreaves, P C Brookes, G J S Ross, P R Poulton
    Abstract:

    Abstract The aim is to assess whether soil microbial biomass carbon (biomass C) could be used as an indicator of environmental change in natural and semi-natural ecosystems. Biomass C was measured by fumigation–extraction in soils from two sites at Rothamsted. One was a plot from the Broadbalk Wheat Experiment, given inorganic fertiliser and chalk, which has been in continuous cultivation for more than 150 yr. The other was a similar sized area, from Geescroft Wilderness, which has been left to revert to woodland since 1885, after being an arable field. Other soil properties (pH, soil organic C and exchangeable cations) were also measured to compare with biomass C. The coefficients of variation (cvs) of the properties measured were calculated for comparison, little difference was found between the cvs for biomass C from each site: cv=26% for Broadbalk and 23% for Geescroft. The cvs for the other, chemical properties, were mostly 25% for Geescroft, as expected, given the different cultivation histories. Statistical analysis of the variation in biomass C concentration revealed that such measurements would not be valid indicators of environmental change, without processing impossibly large numbers of samples. To decrease the least significant percentage change to less than 5% after three samplings, 320 samples would have to be taken each time. This would be also be true of the other chemical properties in Geescroft Wilderness, where the measured background variation would mask any subtle environmental change. This indicates that, for some properties at least, statistically significant changes will only be detected in the longer term with regular sampling, e.g. 30–40 yr.

  • soil microbial biomass c n and ninhydrin n in aerobic and anaerobic soils measured by the fumigation extraction method
    Soil Biology & Biochemistry, 1991
    Co-Authors: Kazuyuki Inubushi, P C Brookes, D S Jenkinson
    Abstract:

    The Fumigation-Extraction method was tested to see if it could be used to measure soil microbial biomass in waterlogged soil. Three Japanese paddy soils were incubated, aerobically or anaerobically (waterlogged), before being fumigated with CHCl3 and extracted by 0.5 m K2SO4. CHCl3-fumigation caused large increases in K2SO4-extractable C, N and ninhydrin-N in the aerobic soils, as observed previously. Fumigation caused smaller, but comparable, increases in waterlogged soils. The biomass, measured as K2SO4-extractablc C released by CHCl3. declined only slowly, if at all, during an 80 day aerobic incubation. However, under waterlogged conditions K2SO4-extractable C released by CHCl3 declined significantly: in 40 days by 11. 22 and 26% in the three soils. Aeration of waterlogged soils for up to 1 h before extraction did not change the amount of K2SO4-extractable C released by CHCl3. This suggests that O2 does not need to be rigorously excluded during the sampling or analysis of waterlogged soils. Microbial biomass C (BC) in aerobic soils can provisionally be calculated from the relationship BC = 2.64 EC. where EC is the organic C extracted by 0.5 m K2SO4 from fumigated soil, less than extracted from the non-fumigated control.

Harvey Bolton - One of the best experts on this subject based on the ideXlab platform.

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