Download Flevopolder experimental fields

Five yrs of research on reduced tillage and
earthworm populations – what did we learn?
Mirjam Pulleman, Stephen Crittenden, Walter Andriuzzi, Tamila
Eswaramurthy, Ron de Goede, Rosanne Michielsen, Bas
Oudshoorn, Guenola Pérès, Tamas Salanki
Content
 Effect of soil disturbance on the soil community
 Why earthworms?
 Reduced tillage; the Dutch context
 Objectives and hypotheses
 3 Related projects
o Hoeksche Waard – arable fields & field margins
strips
o Flevopolder experimental fields - organic &
conventional farming
o SUSTAIN project – Brittany vs. NL
 Results and discussion + future work
Effects of disturbance on soil community
 Direct mechanical damage to body structures
 Disruption of existing physical structure
 Redistribution of litter / crop residues
 Exposure to predation
 Larger sized organisms affected most
 More fungal
dominated
Hendrix et al 1986
Wardle 1995
Effects of disturbance on soil community
Bouché 1977
Wardle 1995: Responses to perturbation are best studied
at a finer taxonomic resolution than normally used for
investigating soil food webs; by emphasizing functional
groups based on ecological relationships (e.g. fungi) or
trophic interactions (e.g. nematodes).
Why focus on earthworms?
 Large organisms, key stone species
 Soil ecosystem engineers – affect habitat for other
organisms
 Soil functioning (depending on functional group)
 Emblematic species....
Keith & Robinson, 2012
Why focus on earthworms?
Reduced soil tillage; the Dutch context
 99% of arable land in NL is regularly mouldboard
ploughed
 Farmers express a growing interest in reduced tillage
 No-till is not practiced  non-inversion tillage
Reduced soil tillage; the Dutch context
 99% of arable land in NL is regularly moldboard
ploughed
 Farmers in NL have a growing interest in reduced tillage
 No-till is not practiced  non-inversion tillage
All with controlled traffic lanes
Objectives and hypotheses
To determine the effects of Ploughed (P) vs. Non-Inversion
Tillage (NIT) systems on the density and diversity of
earthworms (species and functional groups)
 H1: Total earthworm densities will increase in NIT
 H2: The contribution of epigeic and anecic species
will be higher under NIT than P
The projects (2009-2014)
1. Farmers fields Hoeksche Waard
2. Flevopolder, PPO experimental fields
3. Brittany vs. NL (SUSTAIN project)
3
2
1
Farmers fields - Hoeksche Waard
Farmers fields - Hoeksche Waard
Crittenden et al 2015
 Soil: Calcareous marine clay loam
 Conventional farms, each with tillage pairs (1-4 yrs) and
field margin strips as a non-disturbed reference (5 – 9
yrs)
Farmers fields - Hoeksche Waard
Crittenden et al 2015
Sampling method:
o Four 20x20x20 monoliths per sampling location
o Formaldehyde extraction
o Spring and fall samplings (t=4)
Farmers fields - Hoeksche Waard
Crittenden et al 2015
Results tillage pairs
o
Farmers fields - Hoeksche Waard
Crittenden et al 2015
Results field margins:
o
Flevopolder experimental fields
Flevopolder experimental fields
 Marine loam soils
 NIT vs. P, since 2008
 Sampling in 2009, 2010,
2011, 2012, 2014
 3 monoliths per plot
(n=4)
I
III
II
IV
Situation 2011
CONVENTIONAL
ORGANIC
Onion
Wheat/Faba bean
intercrop + CC
Potato
Potato
Sugar beet
Grass-clover
Wheat or Barley + CC
Cabbage
Spring wheat + CC
Crittenden et al 2014
Carrot + CC
Flevopolder experimental fields
Crittenden et al 2014;
Oudshoorn 2013
Results Conventional farming
o
ns
Crittenden et al 2014
ns
ns
MT=NIT>P
Flevopolder experimental fields
Crittenden et al 2014;
Oudshoorn 2013
Results organic farming
o
ns
P>NIT=MT
P>NIT=MT
ns
BRITTANY VS. NL
Brittany vs. NL
Results SUSTAIN - Organic
o
Results and discussion
H1: Total earthworm densities will increase in NIT
Data on total earthworm densities were highly variable,
but when a sign difference of tillage is found:
ORG: NIT/MT < P
CONV: NIT/MT > P
Endogeic species are very dominant (>80%)
Results and discussion
H2: The contribution of epigeic and anecic species
will be higher under NIT than P
The relative importance of epigeic species is increased
under reduced tillage
Anecics are extremely rare in arable fields (but not in
France!)
Anecics are present in grassy field margins
Future work
Reduced soil disturbance:  Earthworm diversity
Increased OM inputs:  Earthworm densities / biomass
Dispersal and survival and dispersal of anecics in(to) NIT fields?
Generalizations across sites with different species (classifications)