five yrs of research on reduced tillage and earthworm populations – what did we learn? mirjam...
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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
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).
Bouché 1977
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....
Why focus on earthworms?
Keit
h &
Robin
son,
2012
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
All with controlled traffic lanes
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
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)
2
3
1
Farmers fields - Hoeksche Waard
Farmers fields - Hoeksche Waard
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)
Crittenden et al 2015
Farmers fields - Hoeksche Waard
Sampling method:
o Four 20x20x20 monoliths per sampling location
o Formaldehyde extraction
o Spring and fall samplings (t=4)
Crittenden et al 2015
Farmers fields - Hoeksche Waard
Results tillage pairs
o
Crittenden et al 2015
Farmers fields - Hoeksche Waard
Results field margins:
o
Crittenden et al 2015
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)
CONVENTIONAL ORGANIC
Onion
Cabbage
Wheat/Faba beanintercrop + CC
Sugar beet
Wheat or Barley + CC
PotatoPotato
Carrot + CC
Grass-clover
Spring wheat + CC
I III
II IV
Situation 2011
Crittenden et al 2014
Flevopolder experimental fields
Results Conventional farming
o
Crittenden et al 2014
Crittenden et al 2014; Oudshoorn 2013
ns ns ns MT=NIT>P
Flevopolder experimental fields
Results organic farming
o
Crittenden et al 2014; Oudshoorn 2013
ns P>NIT=MT P>NIT=MT ns
F K A
FKO
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)