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2.2.4. Biochemical analyses Microbial Biomass C 40 Soil sampling was performed twice in the year 2006: in the middle of the growing season, in June and in the end of the growing season, in October. For each sampling date 8 soil cores were collected. For MBC determination the Fumigation Extraction method (Vance et al., 1987) was used. In brief, two portions of moist soil (20 g oven-dry soil) were weighed, the first one (non fumigated) was immediately extracted with 80 ml of 0.5M K 2 SO 4 for 30 min by oscillating shaking at 200 rpm and filtered with filter paper (Whatman n. 42); the second one was fumigated for 24h at 25 °C with ethanol-free CHCl3 and then extracted as described above. Organic C in the fumigated and non fumigated extracts was determined after oxidation with 0.4 N K 2 Cr 2 O 7 at 100°C for 30 min. Microbial C was calculated as a difference between C content in fumigated and non fumigated extracts divided by a conversion factor (KEC: 0.38). 2.2.5. Statistics Each measurement plot of soil respiration was considered as experimental unit, the replicate measurements were averaged for further analyses, so that soil CO2 efflux for each date represents the average of all the plots. Standard error (SE) of mean was calculated to provide a measure of the variance for aboveground and belowground biomass and soil respiration flux measurements. Multiple linear regression analysis was used to evaluate the contribution of GPP of various times after the measurements to soil CO2 efflux from soil. Nonlinear regression analyses were performed to estimate the effect of temperature and soil water content on soil respiration of different origin. The significant of all the regression coefficients were tested using STATISTICA (Stat Soft).
2.3. Results CO 2 (µmol m -2 s -1 ) CO 2 (µmol m -2 s -1 ) T ( o C); SWC(%) 12 10 8 6 4 2 0 12 10 8 6 4 2 0 45 40 35 30 25 20 15 10 5 0 14.12.05 (a) (b) (c) Ts 24.03.06 Ra Rh SWC 2006 2007 2008 02.07.06 10.10.06 18.01.07 28.04.07 Fig. 2 Seasonal and inter-annual variability of CO2 efflux originating from a) total soil respiration 2006-2007- 2008 b) root-derived (Ra) and microbial-derived (Rh) soil respiration in 2006-2007-2008 (± SE) c) Soil temperature (Ts) and Soil water content (SWC) at 5 cm depth in 2006-2007-2008. 06.08.07 14.11.07 22.02.08 01.06.08 09.09.08 18.12.08 41
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Page 4 and 5: explain diurnal and seasonal change
Page 6 and 7: sull’intensità del flusso respir
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Page 11 and 12: 1. INTRODUCTION AND OVERVIEW 11
Page 13 and 14: times as much carbon as the terrest
Page 15 and 16: Fig. 3 Different soil C pools with
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Page 21 and 22: For grasslands, the nature, frequen
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Page 31 and 32: Houghton R.A., 2003. Revised estima
Page 33: Vleeshouwers L.M., Verhagen A. 2002
Page 36 and 37: 2.1. Introduction 36 Soil respirati
Page 38 and 39: 38 In the year 2005 ten PVC collars
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Page 44 and 45: CO 2 efflux (mmol m -2 s -1 ) 44 CO
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Page 48 and 49: 48 Q10 R 2 p Rs 2.51 0.77 0.000 Ra
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Page 58 and 59: measurements, the possibility to fi
Page 60 and 61: and Schlesinger, 1992; Moyano et al
Page 62 and 63: Janssens I.A., Pilegaard K., 2003.
Page 64: Xu X., Kuzyakov Y., Wanek W., Richt
Page 67 and 68: 3.1. Introduction Soil respiration
Page 69 and 70: Our experiment was conducted in a m
Page 71 and 72: Lactic acid 13 C 13 CO2 Root-derive
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Page 79 and 80: Total Label Recovered (TLR, %) Ra R
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Page 87 and 88: Gavrichkova O., Kuzyakov Y., 2008.
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Chapter source: 90 4. THE EFFCT OF
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Bardgett et al. (1997) showed that
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94 Partitioning plots were installe
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Microbial C was calculated as a dif
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taken from 1 µg N-NO2 ml -1 soluti
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ates between clipped and unclipped
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Fig. 7 Total (Rs), root (Ra)- and m
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104 Rh, (CO 2 , mmolm -2 s -1 ) 7 6
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Fig. 11 Cumulative microbial respir
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108 After the calculation of synthe
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Fig. 16: a) Relationship between sy
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an annual mowing the measurement wa
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mineral N available to plants and N
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Cambardella C.A., Elliott E.T., (19
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Rice C.W., Moorman T.B., Beare M, 1
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120
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5.1. Introduction 122 Nitrogen (N)
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specie, c) an additional aim was to
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5.2.4. Sampling and analyses 126 Na
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the differences between N and contr
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130 specific root respiration (max
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Fig. 4 a) Intensity of 14 CO2 efflu
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Fig. 6 a) values above zero: root-d
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136 Zea mays: A clear diurnal dynam
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plants. The growth stage could cont
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nitrates. At temperatures of 15 - 2
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experiment could be responsible for
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Horwath W.R., Pretziger K.S., Paul,
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146
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148 6.1 . Introduction In studies o
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Regression analyses technique, whic
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152 The respiratory response with g
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154 100% 80% 60% 40% 20% 0% 85% 13%
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6.3.2. 2008: Mesh- exclusion vs. re
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6.4. Discussion 6.4.1. Mesh-exclusi
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introduction in a small soil sample
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component, expressing a total soil
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Kucera C.L., Kirkham D.R., 1971. So
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Acknowledgements This work was poss
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