This document summarizes an organic agriculture conference that discussed subsoiling techniques. It notes that subsoiling effects often disappear quickly, but can be maintained by rapid root development from cover crops. Conference attendees tested various subsoiler designs in different soil types, finding that deeper subsoiling is needed along with wider points and more powerful tractors to fully loosen compact soils. Future work is planned to better understand how subsoiler tine and point geometry affects soil loosening at various depths.

1. Acorn
conference.
November
23,
2015,
Denis
La
France,
dta,
Expert
in
organic
agriculture
–
Anne
Weill,
agr.,
Ph.D.

2. ! CETAB+
Team
§ Eve
Cayer,
agr.,
Sam
Chauvette
agr.,
M.Sc.,
Aurélie
Demers,
dta.,
Jean
Duval,
agr.
Ph.D.,
Audrey
Fréchette,
Pierre
Antoine
Gilbert,
agr.,
M.Sc.,
Denis
La
France,
dta,
Louis
Rousseau,
B.Sc.,
Audrey
Ross,
dta.,
Joshua
Bougon-­‐Ronin,
Anne
Weill
Ph.D.
! Pierre
Bournival,
Eng.,
M.Sc.
Teacher,
Cégep
régional
de
Lanaudière

3. ! Sébastien
Angers
(Ferme
Rheintal)
! Jean-­‐François
Arpin
(Ferme
l’Arche
du
Ruisseau)
! Simon
Audette
(Ferme
Monlou
et
filles)
! John
Bastian
(Ferme
Morgan)
! Alain
Courchesne
(Ferme
Alain
Courchesne
et
Rachel
Cloutier)
! Jean
Leclerc,
dta.,
enseignant
au
Cégep
de
Victoriaville
! RDR
Grains
et
semences
inc.

4.
! Agritex
Yamaska
(John
Deere)
! Centre
agricole
Yamaska
Inc
(Case
IH)
! Comptoir
agricole
de
Sabrevois
(Jo-­‐ber)
! Kverneland
Canada
! La
Sole
Inc.

5. ! Often
subsoiling
effect
disappear
quickly
! Stabilizing
with
rapid
root
development
helps
maintain
effects
! To
subsoil
established
green
manure
(undersown
clovers
after
cereal
harvest)
and
hay
fields
so
that
roots
colonize

10. ! To
subsoil
established
green
manure
(undersown
clovers
after
cereal
harvest)
and
hay
fields
! Allow
roots
to
stabilize
loosened
soil
§ Identify
subsoilers
that
don’t
damage
the
crops
§ Loosen
the
soil
properly
§ Raise
the
yields
in
following
years

11. ! 3
straight-­‐leg,
narrow
point
subsoilers
§ Panbuster:
developped
in
Ireland
for
grassland
§ Jober
(Parabolic
type)
§ Yeomans:
Australian
with
possibility
of
adding
weed-­‐suppressing
sweeps
! Sandy
loam
and
loam
on
glacial
till

16. 30
cm

18. 30
cm

19. ! In
sandy
loam
and
loam
on
till,
insufficient
loosening
! One
exception
with
Loam
(till)
! Jober
(Parabolic)
works
better

20. ! Insufficient
loosening
of
profile
! Solutions
:
Work
deeper,
closer
spacing
of
tines,
wider
points
! Depth
limited
by:
§ Traction
capacity
of
tractors
§ Machine
design
features:
• Yeomans
very
difficult
to
pull
• Panbuster
conceived
for
work
at
30-­‐35
cm

21. ! Deeper
work
=
wider
loosening

22. ! Panbuster,
Yeomans
&
farmer-­‐owned
machines
§ Unverferth-­‐straight-­‐tines,
§ John
Deere
et
Will-­‐Rich
–
curved-­‐tines
and
winged
! More
powerful
tractors
! 3
farms
(4
sites):
Sandy
loam,
loam,
compact
heavy
clay,
very
compact
heavy
clay
! Ordered
wide
points
on
Panbuster-­‐
received
wrong
parts

24. ! Only
one
machine
works
deeply
(45
cm)
§ (Unverferth
–
narrow
points)
!
350
Hp
tractor-­‐
soil
very
dry
and
hard

25. Only
top
part
loosened-­‐
Underneath
smearing
MOISTURE?
SOIL
TYPE?
TINE
GEOMETRY?

28. ! Review
of
literature
to
better
understand
how
tines
and
points
work.
! Discussions
with
Dick
Godwin.
! Planning
a
demonstation
with
wide
range
of
subsoiler
types
to
understand
how
tines
and
points
work.

29. ! Straight
legs
! Curved
legs
! Parabolic
legs
! Narrow
and
winged-­‐points
! Disk
ripper
! In
autumn
4
&
6
tine
parabolic

30. Loosened
soil
Soil
compressed
by
the
tines
Loosened
soil

31. ! Insufficient
loosening
of
soil
profile
! Tractors
not
powerful
enough,
often
poorly
balanced
! Easy
to
subsoil
when
not
too
compact,
very
difficult
when
very
compact
(80
Hp
/
leg
is
needed)
! Security
systems
are
too
week
! Smearing
even
after
prolonged
drought

32. 25
cm
35
cm
(one
leg
removed)

38. ! Why
deeper
smearing
in
very
dry
soil?
! Narrow
or
wide
points/wings?
! Straight,
curved
or
parabolic
legs?
! Spacing
between
legs?
! Best
rake
angle?
! How
much
lift
height
is
best?
! How
to
succeed
in
really
hard
soil?
! Review
of
literature
:
answers
come
from
work
of
Dick
Godwin
&
Gordon
Spoor

44. Working
depth:
40
cm
Central
tines
spacing
OK
Whole
profile
is
loosened
40
cm
deep
Very
good
for
reduced
tillage
systems
Parabolic
V-­‐frame

51. ! Working
depth
-­‐
Required
power
(hp/
tine)
! 30
cm
50
HP
! 40
cm
75
HP
! 50
cm
125
HP

53. ! We
still
have
questions.
! Answers
are
site-­‐specific
! See
our
document
–
CETAB+
site,
edited
by
Anne
Weill
with
help
from
Dick
Godwin
et
Gordon
Spoor
http://www.cetab.org/system/files/publications/weill_2015._guide_to_successful_subsoiling._cetab.pdf