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? Keith & Robinson, 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 ( ) 1. Farmers fields Hoeksche Waard 2. Flevopolder, PPO experimental fields 3. Brittany vs. NL (SUSTAIN project) 2 3 1

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

 Marine loam soils  NIT vs. P, since 2008  Sampling in 2009, 2010, 2011, 2012, 2014  3 monoliths per plot (n=4) CONVENTIONALORGANIC Onion Cabbage Wheat/Faba bean intercrop + CC Sugar beet Wheat or Barley + CC Potato Carrot + CC Grass-clover Spring wheat + CC IIII 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 MT=NIT>P

Flevopolder experimental fields Results organic farming o Crittenden et al 2014; Oudshoorn 2013 ns 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)