Yvan CAPOWIEZ

(INRA Avignon)

and colleagues:

- Chris Moran (univ. Canberra)

Alain Pierret (IRD, Laos)

- S. Sammartino and E. Michel

(INRA Soil Science Avignon)

- H. Boizard (INRA Agronomy Mons)

radiotracking

3D reconstructions

Main topic :

Physical effects of earthworms behaviour (burrowing and

casting) on the soil functionning

… the most accepted and known effects but rarely

quantified due to the lack of adapted tools.

Scientific areas :

- soil ecology (interactions between earthworms)

- agronomy (soil regeneration, water infiltration)

- ecotoxicology (a link between effects at the individual

level and soil functions)

METHODS

* Burrowing

- X-ray tomography (snapshots)

- radiotracking (dynamical)

- 2D terraria (easy and cheap)

} Simulation

model

* Cast

Production

- X-ray tomography (underground casts)

- sieving -> a new

biomarker (ecotox.)

Not all these tools are relevant at the field scale…

SCALE : Example 1 (field study)

Can earthworm regenerate compacted soil under natural

(crop) conditions (if yes, at which rate ?)

CONTROL COMPACTED

M+

1 (

03

/20

05

) M

+8

(11

/20

05

)

Soil core

(Diameter

= 16 cm

Height

= 35 cm)

M+

24

(0

3/2

00

7)

Functional consequences (water infiltration - Beer Kan method)

0

100

200

300

400

500

1 8 24

Months after compaction

Infi

ltrati

on

rate

(m

m h

-1)

Control

Compacted

*

*

SCALE : Example 2 (laboratory conditions)

Do burrows of endogeic species influence water

infiltration ? (if yes, what are the most effective burrows?)

1ew

(3ew)

7ew

1 week 3 weeks 4 weeks

NB : 2 replicates => 32 soil cores

5ew

(2 weeks)

Step1 :Burrow volume in function of time and ew number

Step 2: Burrow system characterisation and rain simulation

-> time for breakthrough of water

0

10

20

30

40

50

60

70

80

90

0 1 2 3 4 5

Time (weeks)

Vo

lum

e (

cm

3)

1 ew

3 ew

5 ew

7 ew

Scale1

Effluent

Rainfall simulator

Scale2 0

50

100

150

200

0 0.5 1 1.5 2

Core

wei

ght

vari

ati

ons

(g)

time (hour)

Step 3: regression between breakthrough time and the

characteristics of the burrow systems in each core

Continuity of the

burrow system

But this is only a correlative approach ….

To go deeper into processes …

Water (50-70%) in

macropores

Scale1

Effluent

Rain simulator

Flux

Scale 2

Core weight dynamics Breakthrough time

Q1: which macropore are active ?

Q2: what kind of flux (laminar, droplets, …) ?

The core is scanned 20 times during a one-hour rain simulation