The usefulness of isotopes in soil studies - PowerPoint PPT Presentation

Loading...

PPT – The usefulness of isotopes in soil studies PowerPoint presentation | free to download - id: 1c581f-ZDc1Z



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

The usefulness of isotopes in soil studies

Description:

The usefulness of isotopes in soil studies – PowerPoint PPT presentation

Number of Views:75
Avg rating:3.0/5.0
Slides: 49
Provided by: eusoilsJr
Learn more at: http://eusoils.jrc.ec.europa.eu
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: The usefulness of isotopes in soil studies


1
The usefulness of isotopes in soil studies
Peggy Macaigne, Ispra 2008
2
  • Introduction what are isotopes ? How to use
    them?
  • Radionuclides in erosion studies
  • Examples of studies with stable isotopes
  • Understanding salinization (North-East Thailand)
  • Reducing of nitrate leaching in potato fields
    (Quebec, Canada)
  • Enhancing water use efficiency (Vienna, Austria)

3
1. What are isotopes ?
  • Elements of same atomic number (protons) but of
    different mass (neutrons)
  • Some are STABLE no disintegration, no
    radioactivity
  • Some are UNSTABLE  or radioactive
    disintegration, emission gamma, alpha, beta, half
    life (?)

4
? 53.28 d
? 5730 y
? 1.6 My
Chart of light element isotopes (Clark, I. and
Fritz, P., 1997)
5
1. How to use isotopes ?
  • As tracer of phenomenon
  • Either with natural abundance of the element to
    be followed from different sources (eg.18O, 2H in
    precipitations)
  • Or with enrichment (eg. 15N in fertilizer, 32P)

6
1. How to use isotopes ?
  • 13C (CID) to study salinity and drought tolerance
    of plants (breeding purposes) some advances to
    relate it to environmental effect
  • 15N to measure nitrate use efficiency or
    follow-up its pathway through soil
  • 32P enrichment to track phosphorus use efficiency
    by plant

7
1. How to use isotopes ?
  • Radionuclides as chronometer
  • Absolute dating Age estimation based on activity
    radionuclide of the object (14C, 232Th)
  • Estimation of exposure to fallout radionuclides
    (137Cs, 210Pb, 10Be, 7Be )

8
2. Radionuclides in erosion studies
  • Methodology comparison of the FRN activity at
    individual points with a reference site, where
    no erosion nor deposition
  • 137Cs for medium-term processes (50 years)
  • 10Be for long term processes (?1.6 My)
  • 7Be for short term processes (?53 d)
  • 210Pb (?22.3 My)

9
3. Project 1 Thailand
  • Context North-East Thailand, paddy field, saline
    patches related to evaporites which processes
    and when does it appears?

10
Evaporation induces isotopic enrichment of soil
water
Instantaneous soil evaporation rate with Cl or
Deuterium (2H) profiles
(Clark, I. and Fritz, P., 1997) Barnes and
Allisons soil evaporation model
11
Grünberger, Macaigne and al, 2008
12
3. Results
  • Model with Hydrus 1 salt essentially comes from
    zone 0-40 cm already present in soil at the end
    of the wet season
  • Outside saline spot close box without any
    connection with aquifer during the year
  • Inside saline spot connection to the aquifer
    during flooding
  • Data and model with Cl and isotope D (2H) shows
    Dual Evaporation comportment
  • 1.saline spot results from a strong
    Cumulated Evaporation,
  • 2. but Instantaneous Evaporation (Barnes
    Allisons model) shows that at the end of drying
    period evaporation is 49-63 lower inside saline
    spot than outside
  • Salinity does not come from capillary ascent
    during dry season

13
Soil-Plant-Water system
  • More studies are needed on
  • Soil-Plant-Water system
  • Improve water-nutrient management under different
    water limited conditions
  • Reduce N-fertilizer losses and improve water use
    efficiency

14
4. Study 2 nitrate leaching lossesin potato
fields
  • Context Continental Canadian Climate
  • St-Ubalde, Québec (/- 40C)
  • Cropping season May to September
  • Soil Freeze snow cover from October to April
  • Rainfed Potato production (no irrigation)

15
4.Study 2 nitrate percolation lossesQuébec,
Canada
Problems Eutrophisation methemoglobinemia
Rainfalls
NO3-
Wells
runoff
River
Tap water
16
4. Study 2 nitrate leaching lossesin potato
fields
  • Objective To reduce N-fertilizer losses
    through water percolation
  • Question
  • How does the Spring snow cover and rainfalls
    influence nitrate leaching ?

17
4. Study 2 nitrate leaching losses in potato
field
  • Rainfall collected every 15 days for 18O 2H
  • Snow cover
  • 1.3 15NH4-15NO3 at planting
  • 5 soil sampling events to 80 cm (May 2005- May
    2006) at
  • Spring after snow melt
  • mid season
  • Harvest
  • Fall
  • next Spring

18
Soil Sampling
Center row
Inter row
0-80 cm soil profile loamy-sand (mixed, acid,
mesic Typic Haplorthod)
Potato production (Solanum tuberosum L.)
19
(No Transcript)
20
21
Precision d 18O 0.1 VSMOW d 2H 1
VSMOW
Y 7.65 x 10.39 R² 0.98
World meteoric ligne, (Craig, 1961) d D 8
d18O 10
Data reliability
21
22
profondeur
18O - 20 to - 8 VSMOW 2H - 155 to - 55
VSMOW Rainfall 12-26 sept - 8 - 51
VSMOW Rainfall 10 -24 oct - 18 - 127 VSMOW
Local meteoric water line provides information on
Soil water evaporation
Sampled 27 Oct. 2005
22
Results 15N in soil
  • 15N (d) Results

Centre hill
Depth (cm)
4 May 05
20 July 05
12 Sep 05
27 Oct 05
5 May 06
Inter-row
23
N-Fertilizer use efficiency (plant uptake)
  • N applied 178 kg N ha-1

15N
Total plant
Tuber
Leaves
Stem
Roots
DM (kg ha-1)
Nrecovered ()
Tuber
DM (kg ha-1)
Nrecovered ()
24
Résultats 3. Influence de la minéralisation
33
Modèles Century (Substor-DSSAT)
(2005)
190
132
134
112
84
25
Conclusion Water movement and N use efficiency
Perceptual model 1st period from harvest to
Spring
  • Water percolation
  • Low soil evaporation
  • Fast water percolation was directly linked to
    strong rainfall intensity gt 60-70 mm/day

18O 2H
  • Nitrates leaching
  • N fertilizer almost disappeared from 0-80 cm zone
    after stong Fall rainfalls
  • Fertilizer totally disappeared the following
    spring

15N
Quick leaching due to strong rainfalls and snow
cover melting, no plant uptake
26
Conclusion Water movement and N use efficiency
Perceptual model 2nd period from Spring to
harvest
  • Water circulation
  • Plant water uptake
  • High soil evaporation
  • Slow percolation of water in top soil layer,
    since rainfalls lt 60 mm/d

18O 2H
Nitrates leaching 1st half of the season low
rainfalls few leaching of fertilizer
2nd half of the season rainfall gt 60 mm/d
dilutes fertilizer laterally
15N
Few N leaching due to low rainfall, strong plant
uptake
27
Study 3 Pilot project at IAEA (Seibersdorf,
Austria)
  • How does Plant uptake water at field capacity and
    under water stress?
  • Establish a relationship between the isotopic
    signatures of soil, plant and irrigation water
  • Pot experiment with 2 levels of soil moisture
    Field capacity, water stress level (30-60 of
    field capacity)

28
5. Study 3 IAEA (Seibersdorf, Austria)
29
5. Study 3 IAEA (Seibersdorf, Austria)
30
5. Study 3 IAEA (Seibersdorf, Austria)4 plant
development states 4 sampling events
2/ 6 weeks
3/ Flowering stage
1/ 3 weeks
4/ Maturity corn cob
31
Isotopes as tools to improve knowledge of
soil-plant-water system
  • 18O and 2H are useful tools to trace water
    within Soil and Plant system
  • Direct individual precipitation or irrigation
    water (? isotopic signature) percolation, water
    uptake, transpiration
  • Indirect Soluble nutrients leaching

32
Isotopes as tools to improve knowledge of
soil-plant-water system
  • 15N is useful tool to investigate
  • N-fertilizer movements through soil
  • N-fertilizer use efficiency

33
Isotopes as tools to improve knowledge of
soil-plant-water system
  • Radionuclides are tool to investigate
  • Soil erosion (10Be, 137Cs)
  • P-fertilizer use efficiency (32P)

34
Acknowledgements
  • U.Paris XI L. Mercury, J.L.Michelot, IRD
    O.Grünberger
  • U.L F. Anctil, L.E. Parent, N. Samson, A.C.
    Parent
  • Agriculture Canada M. Chantigny
  • IAEA L.Nguyen, G.Hardarson, L.Mabit, J.
    Adu-Gyamfi, support of the team J. Arrillaga and
    L. Mayr

35
Questions, Ideas, Point of interest?
36
End of presentation andAdditional slides
37
18O - 13 to - 11 VSMOW 2H - 93 to - 82
VSMOW Rainfalls 25 april -9 may 2005 - 13 - 86
VSMOW Snow - 18 - 134 VSMOW
4 may 2005
38
18O - 10 à - 7 VSMOW 2H - 82 à - 61
VSMOW Rainfalls 29 may-18 July - 7 - 46
VSMOW Rainfalls 25 april-9 may (148mm) - 13 -
86 VSMOW
20 july 2005
39
18O - 11 à - 8 VSMOW 2H - 79 à - 74
VSMOW Rainfalls 15-29 August - 11 - 71
VSMOW Rainfalls 29 août-12 sept (68 mm on
31 August) - 10 - 62 VSMOW
12 September 2005
40
18O - 7 à - 15 (-14) VSMOW 2H - 61 à - 115
(-83) VSMOW Rainfalls 30 mars-13 avril 2006 -
13 - 86 VSMOW Rainfalls 13-27 avril 2006 -
12 - 84 VSMOW Snow - 16 - 109 VSMOW
5 mai 2006
41
Snow Profile 2H and 18O
42
Results Circulation of water and nitrogen in
soil
  • Synthesys with a
  • perceptuel model
  • 2 periods
  • 1. From harvest to Spring flat soil, no culture
  • 2. From Spring to Harvest potato, soil hill
  • How does the Spring snow cover influence nitrate
    leaching ?
  • How do rainfalls influence nitrate leaching ?

43
Study 2 IAEA (Seibersdorf, Austria)
44
Cryodistillation line
45
Isotopes in Soils ?
  • Enhancing water and nutriment use efficiency for
    a better management respecting natural resources
  • Fight against land degradation

High precision tools for
46
Soil Water Management
  • Enhancing water and nutriment use efficiency for
    a better management respecting natural resources
  • Fight against land degradation

High precision tools for better investigation
47
Nutriment management
  • Enhancing water and nutriment use efficiency for
    a better management respecting natural resources
  • Fight against land degradation

High precision tools for better investigation
48
Soil Degradation
  • Soil Erosion
  • Following nitrate leaching
  • Soil concervation techniques
  • Fight against land degradation
About PowerShow.com