Soil aggregate-size classes separation

11 downloads 0 Views 2MB Size Report
Location: Le Bec-Hellouin (Normandie, France), oceanic climate. Studied soils: 3 soils managed with permaculture practices (mounds, beds and forest garden), ...
Permaculture practices effect on soil fertility and organic matter distribution in aggregate-size classes de Tombeur Félix1, Valentin Sohy1, Claire Chenu2, Jean-Thomas Cornélis1

1

of Biosystem Engineering (BIOSE), Gembloux AgroBioTech, University of Liège (Uliege), 5030 Gembloux, Belgium 2UMR Ecosys, INRA AgroParisTech, Univeristy Paris Saclay, CNRS, 78850 Thiverval Grignon, France

3

INTRODUCTION The increasing awareness about the negative impacts of modern agriculture (Stoate et al. 2009) has led to the question of a transition towards a resilient and sustainable agriculture model (Ferguson & Lovell 2014). In this regard, micro- or mini-farms inspired from permaculture model (Mollison & Holmgren 1990) and biointensive micro-gardening could potentially play a key role in this transition (Morel et al. 2017). However, these systems have been largely overlooked by soil scientists and generally isolated from scientific research (Ferguson & Lovell 2014).

Permaculture mounds Moundcultivation ; very high maintenance

Permaculture beds Beds cultivation ; very high maintenance

Permaculture forest-garden Vertical strata (tree, shrub, herbaceous); low maintenance

Conventional

None (mineral fertilization) /

Characteristics of cultivation

/

Organic inputs nature Mean annual input (t.ha-1.yr-1)

None

Horse manure

Horse manure

None

/

225-330

225-330

/

Reference plot

b

c

a

a

Conventional practices

Mounds

Beds

Permaculture practices

bc

10

a b

Conventional

a ab a

ab a b

1 P

(OC concentration in g.kg-1 bulk soil in soil aggregate-size fractions)

45 40 35 30 25 20 15 10 5 0

Soil characteristics: Bioavailable major nutrients (P, Ca, Mg, K) extracted with ammonium acetate-EDTA 1M; Cation Exchange Capacity (CEC) by Metson method ; OC & total N with a CN analyzer ; bulk soil densities (excavation method) Soil aggregate-size classes separation (wet-sieving + 250-2000 µm fraction breakdown; Six et al. 1998; 2000):

b

b K

c

ab b a c

ab b a c Mg

Ca

Perma.

a

Pasture Forest garden Mounds Beds Conventional

a

ab bc c

aa a a a

aaaa bab a b b

Occluded 50-250 µm Occluded