Soil carbon sequestration under Miscanthus x giganteus - Jesko Zimmermann

Soil carbon sequestration under Miscanthus x giganteus

A large scale survey

Jesko Zimmermann

Jens DauberMichael B. Jones

Miscanthus

Miscanthus x giganteus

• Ligno-cellulosic or „second generation“ bioenergy crop

• Rhizomatous perennial grass with a C4 photosynthesis

pathway

• Originates in Asia (tropics and subtropics)

• Remarkable adaptability to cool temperate climates

• Introduction subsidised in Ireland

Soil carbon sequestration potential due to physiological features and management practices

Picture: Jens Dauber

Research questions

Research on carbon sequestration mainly on

experimental fields, however differences can be

expected in commercial plots

This study is focused on commercial large-scale

Miscanthus fields in south east Ireland, looking at:

• Soil carbon sequestration

• Initial soil carbon loss

• What is influencing the processes?

Picture: Susannah Cass

Regional-scale study

Sampling

Nested sampling design

A number of soil cores taken at three subplots in a Miscanthus field and an adjacent control site representing the former land-use

Cores divided into three depth and bulked over the sub plot.

Additional cores taken for bulk density

Materials & Methods

Analyses

The bulked samples were processed in the lab and following measurements were taken:

Total organic carbon

13C/12C stable isotope ratio to determine the Miscanthus-derived carbon (13C natural abundance method)

Soil bulk density, particle size distribution, and pH

Materials & Methods

-10.00 0.00 10.00 20.00 30.00 40.00

Control

Miscanthus

Control

Miscanthus

Control

Miscanthus

10

20

30

SOC [Mg ha-1]

Dep

th [

cm]

C3-derived carbon

C4-derived carbon

-10.00 0.00 10.00 20.00 30.00 40.00

Control

Miscanthus

Control

Miscanthus

Control

Miscanthus

10

20

30

SOC [Mg ha-1]

Dep

th [

cm]

After Zimmermann et al., (2012) Global Change Biology Bioenergy, Vol. 4, Issue 4.

Tillage Grassland

Field-scale study

Picture: Susannah Cass

MG14 TCD_2_1

Average patch area 4.357 m2 3.710 m2

Standard deviation 8.702 25.245

No. Patches 901 1243

Sum of patch area 0.393 ha 0.461 ha

Overall field size 4.390 ha 3.982 ha

Share of field 8.95 % 11.58 %

Zimmermann et al. (in prep.)

Farm Area [m2] SD Radius [m] SD

MT3 8.672 6.287 1.519 0.691

MT5 8.151 4.111 1.570 0.372

MT6 10.595 6.028 1.772 0.496

MG11 18.185 14.109 2.233 0.923

MG18 4.329 1.965 1.146 0.264

MG20 10.488 6.335 1.751 0.537

-50 -40 -30 -20 -10 0

MT6

MT5

MT3

MG20

MG18

MG11

Difference to area of a non-patch field [%]

Farm

High

Medium

Low

Zimmermann et al. (in prep.)

Miscanthus-derived carbon [Mg ha-1]

-0.50 0.50 1.50 2.50

10

20

30

High density

Open patch

-0.50 0.50 1.50 2.50

10

20

30

Tillage Grassland

Zimmermann et al. (in prep.)

Farm scale

-40 -30 -20 -10 0

MG11

MG18

MG20

MT3

MT5

MT6_1

MT6_2

Difference in Miscanthus-derived carbon to a no-patch field [%]

High

Mean

Low

Conclusions

Measurable soil carbon sequestration even 2 to 3 years after planting Miscanthus

No significant loss of soil organic carbon due to plantation

High variability between farms

Crop patchiness has significant impact on yield and soil carbon sequestration

Acknowledgements

David BourkeKees-Jan van Groenigen

Susannah CassKate Harte

Bas BootsKatie WennigCatherine FontanaZeno WongMaximilian von SternburgErin Jo TiedekenSarah Kimberley

The Simbiosys Team

The land-owners for their kind permission to work on their lands

The EPA for funding the project