Quick assessment of soil organic carbon stocks for scaling up issues, using infrared spectroscopy on volcanic soils

Quick assessment of soil organic

carbon stocks for scaling up issues,

using infrared spectroscopy on volcanic soils

AN INNOVATIVE METHOD

RESULTS: SOC STOCKS PREDICTION BY SPECTROSCOPY

NONCRISTALLINE MINERALS, A PROXY OF BULK DENSITY FOR VOLCANIC SOILS?

>

CONCLUSION

CONCLUSION

SOC stocks can be predicted with

satisfactory accuracy and directly by MIR

spectroscopy in volcanic soils.

The 4 per 1000 initiative aims to increase the soil

organic matter content and carbon sequestration

Assessing directly soil organic carbon (SOC) stocks in soils with

spectroscopic techniques is a crucial methodological issue in monitoring

SOC potential sequestration.

ALLO Myriam1_{, TODOROFF Pierre}1_,

JAMEUX Magali1, STERN Mathilde1,

RAMOS Marion1, QUERO Solene1,

ALBRECHT Alain2

1 _{Cirad, UPR AIDA, 97410 Saint-Pierre, Reunion}

² IRD, UMR Eco&Sols, 97410 Saint-Pierre, Reunion

SPECTROSCOPY : A RAPID, LOW-COST

AND HIGH TROUGHPUT ANALYSIS TO

PREDICT SOC STOCKS

An interesting volcanic rock weathering gradient, from Andosols to Ferralsols, in Reunion island

 95 soil samples were collected in sugarcane and pasture plots across the island.

 Prediction models were developed with mid infrared spectroscopy (MIRS) on dried and thieved samples in the laboratory using PLS regression tools to assess SOC stocks.

Laboratory analyses were performed to quantify

short-range-ordered minerals and amorphous

products.

Source : Adapted from Morphopedological Map of Reunion island, 1/50,000, Raunet.M, 1991.

Andosols Haplic Cambisols Andic Cambisols Ferralsols No soil Vertisols Soil map of Reunion island

Bulk Density

C content

*

=

SOC stocks

Amorphous (Al & Si) products are

precisely predicted by spectroscopy.

Bulk density prediction by amorphous products

is particularly accurate. Amorphous products discriminate

the different volcanic soil types in Reunion island.

MIR spectra were recorded on an

Agilent 4300 spectrometer, in the range 650 – 4000 cm-1_. © C IR AD , 20 15 . 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 B D pr edi ct ed ( g.cm -3 ) BD measured (g.cm-3₎

Bulk density prediction

R² = 0.80 RMSE = 0.11 0 10 20 30 40 50 60 70 80 0 10 20 30 40 50 60 70 80 SO C s tock s pr edi ct ed ( t.ha -1 )

SOC stocks measured (t.ha-1₎

SOC stocks prediction

R² = 0.81