Can we infer compositional similarities of soil and plant samples?

Wilfred, Michelle, Geoff

• C/N ratios

• δ13C

• FTIR

Plant litter *

Microbes*

Soil respiration

Litterfall

Modified from Schlesinger 1977

Fulvic Acids Humic Acids*

High N content and low Turnover (100 – 1000 yrs)

years

Temperature

Light

Humidity

Loss

General Plant Soil Interaction

*Non cellular OM

*Cellular OM

0

2

4

6

8

10

12

14

16

0 2 4

%C

Dep

th (

cm

)

Modified from Cox et al. 2000

•Organic content tends to decrease with depth in soil

•Our samples do not have a lot of organic matter

•May be similar to savannas than temperate grasslands (fire?)

Our data

1

2

3

4

5

6

7

8

2 3 4 5 6 7 8 9 10 11

% Organic Content

Soi

l lay

er

Where should we look for organic matter?

Oades 1988 and Jones 1973

Comparison of Averages

Plant std dev Soil std dev

C 43.43 3.65 2.20 1.52

N 1.92 1.33 0.19 0.14

δ13C -21.92 8.08 -19.84 1.53

C/N 31.91 17.05 14.53 1.77

Of the SOM is present, can we infer anything about their origin?

Specific Average Comparison

C3 C4 Roots Top Soil

C 44.90 41.85 43.78 3.21

N 1.10 1.27 1.49 0.28

δ13C -28.14 -13.02 -22.18 -19.52

C/N 44.10 40.25 35.47 13.51

Still an average of C3 and C4 plants

Where are the organics going? Different factors promote or inhibit decomposition

Cellulose

Lignin

Biochemical Constituents

SoilPlants

Fulvic acid

Humic acid

0.00

0.20

0.40

0.60

0.80

1.00

1.20

5001000150020002500300035004000

wave number

Abso

rban

ce

RPP 12 Brown

PRP8 Root

PRP 11 Green

PRS 15 Top soil

Cellulose Karurakova et al 2002

humics

Humics

Aliphaticshumics Si-O

Cell wall material –(Karurakova&Wilson 2001)

• Untreated soil dominated by inorganics and are undifferentiable– Cox et al. 2000, Thorton 1986

• Need thermo-extraction

•Why is soil low in OM?

•rocks

•Fungal decomposition and cow grazing might lower OM in soil.

•Aliphatics and COOH have inverse relationship with humification process – Chen 1997

Cox et al. 2000 Low organics

Root vs Leaf vs Vein

Referenced Literature• Chen L, Wilson R, McCann, MC (1997) Investigation of macromolecule orientation in dry and hydrated walls of

single onion eopidermal cells by FTIR microspectry. Journal of Molecular structure (408-409) 257-260• Cox, RJ, Peterson, HL, Young, J, Cusik, C Espinoza, EO(2000) The forensic analysis of soil organic by FTIR,

Forensic Science International 107-116.• Baldock, JA, Skjemstad,JO (2000) Role of soil matrix and minerals in protecting natural organic materials against

biological attack. Organic Geochemistry(31) 697-710• Gigliotti, G, Businelli, D, Guisquiani, PL (1999) Composition changes of soil humus after massive application of

urban waste compost: a comparison between FTIR spectroscopy and humification parameters. Nutrient Cycling in Agroecosystems (55) 23-28

• GAMBLE GR, SETHURAMAN A, AKIN DE, et al. (1994) Biodegradation of lignocellulose in Bermuda grass by white rot fungi analyzed by solid state C-13 nuclear magnetic resonance APPLIED AND ENVIRONMENTAL MICROBIOLOGY 60 (9): 3138-3144

• Ellerbrock RH, Kaiser M. (2005) Stability and composition of different soluble soil organic matter fractions- evidence from delta 13C and FTIR signatures Geoderma 128 28-37

• Kacurakova, M, Wilson, RH (2001) Developments in midinfrared FT-IR spectroscopy of selected carbohydrates. Carbohydrate Polymers (44) 291-303

• Kacurakova, M. Smith, A. Ridley, G. Wilson, R. (2002) Molecular interactions in bacterial cellulose composites studied by 1D FTIR and dynamic 2D FTIR spectroscopy. Carbohydrate Research 337, 1145-1153

• Oades, JM (1988) The retention of organic matter in soils. Biogeochemistry (5) 35-70• Jones, MJ (1973) The organic matter content of the savanna soils of west Africa. Journal of Soil Science 24: 42-

53• Schlesinger, WH (1977) Carbon balance in terresrial detritus. Annual Review of Ecology and Systematics 8: 51-

81. In Biogeochemistry Analysis of Global Change 2nd ed.

Ellerbrock 1989

Additional information

S+N = straw

LM= manure

Rajulu et al. 2006. Polymer Science

Yanping and Rockshow 2006. Carbon