utilization of isotopes in plant nutritional studies is briefed in this ppt, student of agriculture particularly soil science can make best use of it

2. UTILIZATION OF ISOTOPES IN PLANT
NUTRITIONAL STUDIES
Seminar-I
on
Veerendrapateel, L.
Snr. M.Sc.(Agri)
PG15AGR7121

3. Sequence of presentation:
Introduction
Isotopes- Definition andtypes of isotopes
Application of isotopes
• In Agriculture
• In plant nutrition
Research papers
Conclusion

4. Introduction
An atom….

5. What is an Isotope….?
Atoms of element with different numbers of
neutrons are called "isotopes" of that element
+
+ +
+
+
+
Nucleus
Electrons
Nucleus
Neutron
Proton
Carbon-12
Protons 6
Electrons 6
Neutrons 6
Nucleus
Electrons
Carbon-14
Protons 6
Electrons 6
Neutrons 8
+
+
+
+
+
+
Nucleus
Neutron
Proton

6. The existence of isotopes was first suggested in 1913 by
Frederick Soddy- Radio chemist
England

7. Isotope
s
Stable
Unstabl
e
No. Of protons < no of neutrons No. Of protons > no of neutrons
Unstable atoms have an excess of energy or mass or both
Undergo radioactive decay-
ionizing radiation
Do not undergo radioactive decay
eg; 15N, 31P,18O, 12C etc..
eg; 32P,11C etc..

8. Table 1: Radiations produced by unstable isotope
Type Of
Radiation
Description Electrical
Charge
Relative Damage
To Living Cells
- Radiation Fast moving particles
containing two protons
and two neutrons
Positive Most damaging
- Radiation Fast moving electrons Positive Or
Negative
Most damaging
- Radiation Electromagnetic
radiation, like light
but with A much
shorter wavelength
and higher energy
None Least damaging

9. Applications of Isotopes
Medicine
Archeology
Industrial uses- Na-24 is used to detect the leakage
of underground pipes, in the smoke detectors, help
to control the thickness of plastic, paper and metal
sheets in respective industries
Energy- Radioisotope thermoelectric generators
(RTGs)
Agricultural uses

10. Americium -241

11. Application in Agriculture
Isotopes are used widely in the field of
Crop improvement
Soil fertility and Plant nutrition
Irrigation and Water management
Insect pest control
Livestock production and health
Chemical residue and pollution
Food preservation
Soil conservation

12. Application in Soil fertility and Plant nutrition
• Fertilizer use efficiency & uptake of fertilizers
• Ions mobility in soil and plants
• Metabolism of nutrients by plants.
• Biological nitrogen fixation
• Rate of soil erosion and soil formation.
• Nutrient turnover in soil
• Genotypic difference in nutrient uptake and use
• Recovery of nutrient from crop residues.
• Nitrogen gaseous losses (volatilization and
denitrification)
• Degradation of nutrient among plant parts
• Tolerance of plant for salinity and drought

13. Measurement of fertilizer use efficiency
1) The classical or conventional method based on yield.
2) Methods based on nutrient uptake:
1. Differential method: Indirect method
2. Isotopic method: Direct measurement of uptake from
the applied fertilizer through the use of isotopes.
 Using labeled fertilizer with isotope 15N and radioactive
isotopes 32P or 33P etc.

14. Isotopic labeling…?
Technique to track the passage of an isotope
through a reaction, metabolic pathway.
George De Hevesy- 1943

15. • A radioactive compound is introduced into a living
organism and the radio-isotope provides a means to
construct an image showing the way in which that
compound and its reaction products are distributed
around the organism

16.  In this technique, one/more of the atoms of the
molecule of interest is substituted for an atom
of the same chemical element, but of a different
isotope (radioactive isotope used in radioactive
tracing).
 Used in chemistry and biochemistry:
understand chemical reactions and interactions.

17. Ways to detect the presence of
labelling isotopes
1. Mass- Mass spectroscopy
2. Vibrational mode- IR-spectroscopy
3. Radioactive decay-
 Nuclear magnetic resonance(NMR),
 Autoradiographs of gels- Gel electrophoresis
 Liquid scintillation
 Geiger-Mueller (GM) counters

18. Stable Isotope Analysis (SIA) - 15N, 13C, 18O and 34S
In stable isotope analysis, milligram amounts
of samples are combusted or pyrolysed at high
temperature. After suitable preparation the
measurable gases (N2, CO2, CO or SO2) are
separated on a chromatography column. The gas
species of different masses are subsequently
measured by mass spectroscopy

19. MASS SPECTROMETER

20. Liquid scintillation

21. Geiger-Mueller (GM) tube, also called as GM counter.

22. Element Stable
isotope
Radio
isotope
Typical applications
Carbon 12C 14C Photosynthesis, SOM studies, Carbon balance
Hydrogen 1H 3H Water movement, Biochemical studies
Oxygen 18O, 16O 15O, 13O Photosynthesis, Respiration, Hydrology
Potassium 39K 42K Ion uptake mechanism,
Magnesium 24Mg 28Mg Movement in plant
Sulfur 32S 35S Availability from soil, uptake from soil and air
Iron 56Fe 59Fe Soil erosion, movement in soil and plants
Chlorine 35Cl 36Cl
37Cl
Solute movement in soil, Herbicidal effects on life
forms
Cesium 133Cs 134Cs
137Cs
Soil erosion (sediment movement and deposition)
Boron 11B, 10B 12B Foliar absorption, Soil moisture studies
Molybdenum 96Mo 99Mo Plant nutrition
Table 2. Principal isotopes used in soil-plant studies
Zapata, 1990

23. PHOSPHORUS
Isotope Natural abundance (atom %) Typical applications
13N Trace
 N- fixation
 Denitrification.
14N 99.63  14N enriched materials for single season FUE
15N 0.368
 FUE, biological N fixation
 N transformation in soils (N-cycling)
 Animal nutrition studies.
 Nitrate pollution in groundwater.
Isotope Half life (days) Typical applications
32P 14.26
 Fertilizer use efficiency
 Residual P fertilizer studies
 Root activity pattern of crops
33P 25.34
 Root autoradiography
 Double labelling for root.
 Activity pattern of crops.
 Fertilizer use efficiency.
NITROGEN
Zapata, 1990

24. Principle in use of Labelled fertilizer
“For a known constant amount of
radioactivity, the specific activity is
proportional to the total amount of test
element present in the system”.

25. Specific activity:
Specific activity of standard :
=
𝑵𝒆𝒕 𝒄𝒐𝒖𝒏𝒕𝒔 𝒑𝒆𝒓 𝒖𝒏𝒊𝒕 𝒕𝒊𝒎𝒆 𝒊𝒏 𝒕𝒉𝒆 𝒂𝒍𝒊𝒒𝒖𝒐𝒕 𝒐𝒇 𝒇𝒆𝒓𝒕𝒊𝒍𝒊𝒛𝒆𝒓 𝒔𝒕𝒂𝒏𝒅𝒂𝒓𝒅
𝑻𝒐𝒕𝒂𝒍 𝒏𝒖𝒕𝒓𝒊𝒆𝒏𝒕 𝒊𝒏 𝒕𝒉𝒆 𝒂𝒍𝒊𝒒𝒖𝒐𝒕(𝝁𝒈)
Specific activity of Sample :
=
𝑵𝒆𝒕 𝒄𝒐𝒖𝒏𝒕𝒔 𝒑𝒆𝒓 𝒖𝒏𝒊𝒕 𝒕𝒊𝒎𝒆 𝒊𝒏 𝒕𝒉𝒆 𝒂𝒍𝒊𝒒𝒖𝒐𝒕 𝒐𝒇 𝒑𝒍𝒂𝒏𝒕 𝒔𝒂𝒎𝒑𝒍𝒆
𝑻𝒐𝒕𝒂𝒍 𝒏𝒖𝒕𝒓𝒊𝒆𝒏𝒕 𝒊𝒏 𝒕𝒉𝒆 𝒂𝒍𝒊𝒒𝒖𝒐𝒕 𝝁𝒈 𝒊𝒏 𝒕𝒉𝒆 𝒑𝒍𝒂𝒏𝒕 𝒔𝒂𝒎𝒑𝒍𝒆

26. %𝑵𝒅𝒇𝒇 =
𝒔𝒑𝒆𝒄𝒊𝒇𝒊𝒄 𝒂𝒕𝒊𝒗𝒊𝒕𝒚 𝒐𝒇 𝒑𝒍𝒂𝒏𝒕
𝒔𝒑𝒆𝒄𝒊𝒇𝒊𝒄 𝒂𝒄𝒕𝒊𝒗𝒊𝒕𝒚 𝒐𝒇 𝒇𝒆𝒓𝒕𝒊𝒍𝒊𝒛𝒆𝒓
× 100
% of nutrient derived from the fertilizer:
% Ndfs = 100- %Pdff
% of nutrient derived from the soil:

27. Fertilizer nutrient uptake :
=
%𝑵𝒅𝒇𝒇
𝟏𝟎𝟎
× Total nutrient uptake
=
%𝑵𝒅𝒇𝒇 ×𝑻𝒐𝒕𝒂𝒍 𝒏𝒖𝒕𝒓𝒊𝒆𝒏𝒕 𝒖𝒑𝒕𝒂𝒌𝒆(𝒌𝒈/𝒉𝒂)
𝑹𝒂𝒕𝒆 𝒐𝒇 𝒇𝒆𝒓𝒕𝒊𝒍𝒊𝒛𝒆𝒓 𝒂𝒑𝒑𝒍𝒊𝒄𝒂𝒕𝒊𝒐𝒏 ( 𝒌𝒈/𝒉𝒂)
× 100
% 𝑼𝒕𝒊𝒍𝒊𝒛𝒂𝒕𝒊𝒐𝒏 𝒐𝒇 𝒇𝒆𝒓𝒕𝒊𝒍𝒊𝒛𝒆𝒓 𝒏𝒖𝒕𝒓𝒊𝒆𝒏𝒕 𝒐𝒓 𝑵𝑼𝑬:

28. For example: In a pot culture experiment
• 32P labelled fertilizer containing 100 mg P with an activity of
5000 k Bq is added.
• An aliquot of a plant sample containing 50 mg P gives an
activity of 500 k Bq
• Specific activity of standard or fertilizer P: 5000/100= 50 k Bq
mg-1
• Specific activity of sample: 500/50= 10 k Bq mg-1
• %𝑃𝑑𝑓𝑓= 10/50 ×100 = 50%
• %𝑃𝑑𝑓𝑠 = 100-50 = 50%
• % utilization of fertilizer nutrient = 50 ×50/100= 2.5

29. • For stable 15N same principle applies,
instead of “specific activity” the term “% 15N
atom excess is used”
** since the amount of sample is expressed as %15N atom
excess over the natural abundance of 0.3663. i.e. 14N=
99.63%, 15N= 0.366%
(subtracting 0.3663 from the determination of 15N
abundance to obtain 15N atom excess).
% Ndff =
% 15
𝑁 𝑎𝑡𝑜𝑚 𝑒𝑥𝑐𝑒𝑠𝑠 𝑖𝑛 𝑝𝑙𝑎𝑛𝑡 𝑠𝑎𝑚𝑝𝑙𝑒
%15
𝑁 𝑎𝑡𝑜𝑚 𝑒𝑥𝑐𝑒𝑠𝑠 𝑖𝑛 𝑓𝑒𝑟𝑡𝑖𝑙𝑖𝑧𝑒𝑟
X 100

30. • In a field experiment 70 kg N/ha in the form of 15N labelled
urea fertilizer with 1.566 % 15N excess was applied to a
crop
• The crop was harvested with a dry matter yield of 4 tons/ha
and plant sample had 0.566 % N abundance and 3% total
N.
• % 15N atom excess plant = 0.566 - 0.366 = 0.20
• % 15N atom excess fertilizer = 1.566 - 0.366 = 1.20
• % Ndff: 0.2/1.2 ×100 =16.66
• % Ndfs = 100 – 16.66= 83.33
• Total N yield = 4000 x 3/100= 120 kg N/ha
• Fertilizer N yield = 16.66/100x 120 = 19.99kg N/ha
• % Fertilizer N utilization = 19.99/70 x 100 = 28.56 %

31. Advantages of isotope study
1.With the help of radioisotopes we can easily locate the
presence of a single atom and molecule and their
movement.
2.Very small quantities of labelled nutrients can be
accurately measured in presence of large quantities of
other nutrients.
3.Tracer technique enables one in tracing those elements
taken by the plants accurately and precisely.
4.It also helps to study accurately the interaction among
the mineral nutrients
5. You can label specific atoms (say carbon-1 in glucose)
to follow where each one goes.
6. A radioactive molecule is chemically exactly like the
unlabelled form. Thus, it will behave just like the
unlabeled form so you dont have to worry about effects
due to the labelling itself.
7. Since carbon, hydrogen and phosphorus can be easily
purchased in radioactive forms, you can make any
biomolecule in a radioactive form.

32. Disadvantages:
1. Radioisotopes are rather expensive.
2. Radioisotopes are hazardous and must be handled
with extreme care. By the same token, they present
a disposal hazard.
3. Some radioisotopes (like P-32 and I-125) have short
half-lives, so have to be used quickly.

34. The application of isotopic (32P and 15N) dilution
techniques to evaluate interactive effect of
phosphate solubilizing rhizobacteria, mycorrhizal
fungai and Rhizobium to improve the agronomic
efficiency of of rock phosphate for legume crops
Barea et al. (2002)
Institute of Systematica and Ecology, Cuba
Pot culture experiment

35. Soil Properties
pH : 6.8
Organic carbon (%) : 0.8
Total N (mg kg-1) : 2600
Avail. P (mg kg-1) : 15
Exch Ca. (meq l-1) : 10

36. Material and methods
• Pot culture- Factorial RCBD
• Treatments: 8, Replications: 5
• 4 microbial treatments
1. Rhizobium inoculation- Rhizobium meliloti (WTGR4 isolate)
2. Arbuscular Mycorrhiza(AM) inoculation- Glomus mosseae.
3. PSB inoculation(RB)- Enterobacter sp
4. AM+ RB inoculation
• 2 Chemical treatments
1. Unammended control- without P application
2. Rock phosphate application: 100 mg per pot (11.4% total P)
Plant selected: Alfalfa (Medicago satia L.,)

37. • Plants were fertilized (5 ml wk−1 pot−1)with a basal nutrient
solution (lacking N and P) in the following amounts
• After 10 d of plant growth each pot received a solution of
(15NH4)2SO4 with 10% 15N atom excess, which supplied 2
mg N kg−1 soil. An aliquot containing 1850 K Bq 32P pot−1
was added to obtain sufficient activity in the plant material.
Nutrients Conc. (μmol kg−1) Nutrients Conc. (μmol kg−1)
K2SO4
MgSO4.7H2O
MnSO4.H2O
CuSO4.5H2O
2008
2029
118
100
ZnSO4.7H2O
CaCl2.6H2O
H3BO3
NaMoO4.2H2O
35
21
81
2
• Plants were harvested after 55 d of growth.
• The N isotopic composition of plant was determined by
using an automated N analyzer- continuous-flow isotope
ratio mass spectrometer (ANA–MS method).
• The 32P activity in the plant material was measured by
liquid scintillation counting of the 32P expressed in Bq.
• The specific activity of P was then calculated by
considering the radioactivity per amount of total P content
in the plant and expressed in Bq mg P−1

38. Table 3. Effect of treatments on shoot weight of alfalfa plants
Shoot dry weight (mg pot-1)
Microbial treatment
Chemical treatments
Control Rock phosphate
Rhizobium (WT)
Control 269 390
Rhizobacteria (RB) 290 535
Mycorrhiza (AM) 405 570
RB+ AM 560 618
Barea et al. (2002)

39. Table 4. Effect of microbial treatment on shoot N content and
atom percent 15N excess in alfalfa plants
Microbial
treatment
Chemical treatments
Control Rock phosphate
N content
(mg pot-1)
15N % a.e
N content
(mg pot-1)
15N % a.e.
Rhizobium (WT)
Control 12.8 0.90 15.1 0.93
Rhizobacteria
(RB)
12.1 0.81 25.3 0.65
Mycorrhiza (AM) 20.1 0.60 27.8 0.62
RB+ AM 29.6 0.59 31.2 0.50
15N : 10% atom excess which supplies 2 mg N kg-1
32P: 1850 K Bq 32P pot-1
Barea et al. (2002)

40. Microbial
treatment
Chemical treatments
Control Rock phosphate
P content
(mg pot-1)
32P/Total
P content
(mg pot-1)
32P/Total
Rhizobium (WT)
Control
0.39 2200 0.65 1083
Rhizobacteria (RB)
0.34 2080 1.10 900
Mycorrhiza (AM)
0.81 1333 1.75 650
RB+ AM
1.01 1117 1.85 580
Table 5. Effect of microbial treatment on shoot P content and
specific activity in alfalfa plants
Barea et al. (2002)

41. Fig 1. Effect on dry matter
Barea et al. (2002)

42. Fig 2. Effect on accumulation of N and P (g 10m-2)

43. Assessment of FUE under enhanced crop intensity
of vegetables due to intercropping using 15N and
32P labelled fertilizers.
Kotur et al. (2010)
Indian Institute of Horticultural Research, Bangalore

44. Soil Properties
Texture : Sandy loam
pH : 5.9
Org. N (%) : 0.3
Avail. N (kg ha-1) : 246
Avail P (kg ha-1) : 15.5
CEC (cmol(p+)kg-1) : 8.7

45. Table 6. Yield under different solo crops and their combinations
Treatment
Capsicum*
onion**
Watermelon*
Radish**
Okra*
Frenchbean**
(kg/1.8 m2)
Sole Crop 1* 6.3 15.5 5.6
Sole Crop 2** 2.7 8.9 2.4
Crop
combination$ 4.4 15.6 5.5
S.E.(±) 0.10 0.25 0.14
CD (P=0.05) 0.35 0.88 0.48
*Main crop, ** intercrop, #capsicum-eq in capsicum, onion;
watermelon-eq in watermelon, radish; okra-eq in okra, Frenchbean crop combination,
$crop combination of respective main and intercrop.
15N urea: 1.0 atom%;
32P labelled superphosphate: Specific activity of 0.2mCi/g of P
Kotur et al. (2010)

46. Table 7. Fertilizer N utilization under different solo crops and their
combinations
Treatment
Capsicum*
onion**
Watermelon*
Radish**
Okra*
Frenchbean**
Fertilizer N utilization (%)
Sole Crop 1* 10.85 23.70 22.76
Sole Crop 2** 25.25 37.16 23.10
Crop
combination
6.60 19.12 6.44
S.Em (±) 0.59 0.84 0.82
CD (P=0.05) 2.04 2.92 2.84
Kotur et al. (2010)

47. Table 8. Fertilizer P utilization under different solo crops and
their combinations
Treatment
Capsicum*
onion**
Watermelon*
Radish**
Okra*
Frenchbean**
Fertilizer P utilization (%)
Sole Crop 1* 11.9 4.89 8.24
Sole Crop 2** 7.09 10.43 10.14
Crop
combination
6.18 6.13 9.31
S.E.(±) 0.15 0.13 0.23
CD (P=0.05) 0.50 0.44 0.79
Kotur et al. (2010)

48. Effect of 15N- labelled urea application alone and
in combination with FYM/green manure on rice
yield and NUE by rice.
Battacharya et al. (2006)
Division of Soil Science and Agricultural Chemistry,
Indian Agricultural Research Institute, New Delhi

49. Soil Properties
Soil Type : Typic Haplustept
Texture : Sandy loam
pH : 8.50
EC (dSm-1) : 0.45
Total N (mg kg-1) : 680
O.C. (g kg-1) : 4.4
Avail. N (mg kg-1) : 102
Avail. P (mg kg-1) : 11.2
Avail. K (mg kg-1) : 99.0
CEC (cmol(p+) kg-1) : 9.7

50. Table 9. Treatment details
S.No
Nitrogen rate
(kg ha-1)
Source and notation
1 0 Control
2 90 Urea (U)
3 120 Urea (U)
4 90 2/3 N as urea+ 1/3 N as GM (UG2:1)
5 90 1/2 N as urea+ 1/2 N as GM (UG1:1)
6 120 2/3 N as urea+ 1/3 N as GM (UG2:1)
7 120 1/2 N as urea+ 1/2 N as GM (UG1:1)
8 90 2/3 N as urea+ 1/3 N as FYM (UG2:1)
9 90 1/2 N as urea+ 1/2 N as FYM (UG1:1)
10 120 2/3 N as urea+ 1/3 N as FYM (UG2:1)
11 120 1/2 N as urea+ 1/2 N as FYM (UG1:1)
GM (2.31% N, 0.48% P and 0.61% K); FYM (0.46% N, 0.33% P and 0.44% K)
Battacharya et al. (2006)

51. Table 10. Effect of N levels and its combination with FYM or
green manure on yield of rice
Sources
Grain yield(t ha-1) Straw yield (t ha-1)
N levels (kg ha-1)
90 120 Mean 90 120 Mean
U 5.78 6.62 6.20 8.61 10.39 9.50
UG2:1 5.77 6.66 6.22 8.92 9.72 9.32
UG1:1 5.50 6.25 5.88 7.62 9.55 8.59
UF2:1 5.32 5.73 5.53 8.72 9.52 9.12
UF1:1 5.53 6.17 5.85 7.64 8.52 8.08
Mean 5.58 6.29 - 8.30 9.54
Control - - 4.08 - - 6.26
CD
(P=0.05)
Source NS 0.83
Level 0.33 0.52
S×L NS NS
15N urea: 5.005% atom excess Battacharya et al. (2006)

52. N uptake (kg ha-1)
Sources
N levels (kg ha-1)
90 120 Mean
U 101 134 117
UG2:1 110 125 118
UG1:1 89 118 104
UF2:1 97 114 106
UF1:1 100 113 106
Mean 100 121 -
Control - - 65.6
CD (P=0.05)
Source 9.9
Level 6.3
S×L 14.0
Table 11. Effect of N levels and its combination with FYM or green
manure on total N uptake by rice at harvest
Battacharya et al. (2006)

53. Sources
Grain (%Ndff) Straw (%Ndff)
N levels (kg ha-1)
90 120 Mean 90 120 Mean
U 25.1 24.9 25.1 27.3 33.5 30.4
UG2:1 23.8 29.0 26.4 22.9 28.3 25.6
UG1:1 22.1 22.6 22.4 19.0 22.3 20.7
UF2:1 21.5 27.9 24.7 25.7 26.6 26.1
UF1:1 20.2 25.8 23.0 22.7 21.7 22.2
Mean 22.6 26.1 - 23.6 26.5 -
CD
(P=0.05)
Source 2.48 2.06
Level 1.57 1.30
S×L 3.51 2.91
Table 12. Effect of N levels and its combination with FYM or
green manure on %Ndff of rice grain and straw
Battacharya et al. (2006)

54. Sources
N levels (kg ha-1)
90 120 Mean
U 29.3 31.9 30.1
UG2:1 43.2 47.5 45.4
UG1:1 41.9 41.8 41.9
UF2:1 37.8 38.4 38.1
UF1:1 47.3 45.9 38.1
Mean 39.9 41.1 46.6
CD (P=0.05)
Source 3.5
Level NS
S×L NS
Table 13. Effect of N levels and its combination with FYM or
green manure on nitrogen use efficiency by rice
Battacharya et al. (2006)

55. Sources
NO3-N (mg kg-1) NH4-N (mg kg-1)
N levels (kg ha-1)
90 120 Mean 90 120 Mean
U 3.20 3.38 3.29 6.77 6.95 6.86
UG2:1 3.01 2.58 2.79 6.62 8.82 7.72
UG1:1 2.72 3.02 2.87 7.85 8.82 8.34
UF2:1 2.69 2.66 2.68 6.34 7.60 6.97
UF1:1 2.74 3.38 3.06 7.37 8.19 7.78
Mean 2.87 3.00 - 6.99 8.08 -
Control - - 2.56 6.58
CD
(P=0.05)
Source NS NS
Level NS 2.05
S×L NS NS
Table 14. Effect of N levels and in combination with FYM or
green manure on NO3-N and NH4-N conc. of rice soil at harvest

56. Predicting soil organic matter stability in
agricultural fields through
carbon and nitrogen stable isotopes
Clercq et al. (2015)
Department of Earth and Environmental Sciences, KU Leuven, Belgium

57. Material and methods
• Survey and laboratory analysis
• Places surveyed:
a. Belgium- Boutersem and Gembloux
b. Austria- Gross- Enzersdorf and Grabenegg,

58. Belgium- a. Boutersem
The five treatments sampled for this site are:
1. an unfertilized control,
2. a mineral fertilized control,
3. a three-yearly application of VFG-compost
comprising of 45 tons per hectare
4. two yearly applications of VFG compost
comprising of 15 and 45 tons per hectare.
b. Gembloux
1. Mineral fertilized control
2. Stable manure application

59. Austria- a. Gross- Enzersdorf
Sampling at this site was taken from:
1. Conservation tillage,
2. Conventional tillage and
3. Permanent grass alley
b. Grabenegg
It was a permanent grass land for 15 years

60. Isotope analysis
Carbon and nitrogen content and their
respective stable isotope ratios were analyzed for
the POM fraction and bulk soil with an
• Elemental analyzer coupled with a mass
spectrometer
• For the protected mineral associated organic
matter fraction (mOM), carbon and nitrogen
content were calculated as the difference between
the bulk soil and the POM

61. Concept of relative abundance
For nitrogen standard is the atmospheric air, therefore
Rstd= 0.366/99.633= 0.0036
For sample =…???

62. Fig 3.Model for organic matter stability given by
Conen et al.(2008)
Clercq et al. (2015)

63. Data analysis and calculations
Where,
ẟm & ẟp - ẟ15N for mOM & POM respectivrly
rm & rp- C/N ratio for mOM & POM respectivrly
Cm & Cp - Carbon mass for mOM & POM respectivrly
fC & fN – fractions of C & N lost during degradation
ɳ- relative SOM stability

64. Fig 4. C/N ratio and ẟ15N signature for the SOC
fractions of the experimental sites
Clercq et al. (2015)

65. Table 15. Carbon concentration(mg/g of dry soil)

66. Table 16. Relative stability(ɳ) of soil organic carbon
Clercq et al. (2015)

67. conclusion

68. Thank you