five yrs of research on reduced tillage and earthworm populations – what did we learn? mirjam...

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)