The dominant effects of biota on stability, aggregation ...

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Dec 9, 2016 - organic content distribution of Technosols compared to that of organic matter. 1. Maha DEEB, Thierry DESJARDINS , Pascal PODWOJEWSKI, ...
The dominant effects of biota on stability, aggregation, and soil organic content distribution of Technosols compared to that of organic matter Maha DEEB, Thierry DESJARDINS , Pascal PODWOJEWSKI, Anne PANDO, Manuel BLOUIN, and Thomas LERCH

1st Annual Urban soil symposium 12/09/2016

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Technosols: definition

“Natural” Technic soils

Displaced natural materials > 80%

Artificial materials greater than 20% (Schwartz,2011)

or

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Principle

Constructed Technosols

Green space

Urban waste 1st Annual Urban soil symposium 12/09/2016

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Problematic Urban soils: • • •

1st Annual Urban soil symposium 12/09/2016

Low chemical and physical fertility High heterogeneity Compaction and significant pollution

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Problematic City Deep soil excavation

Deep soil excavation

Countryside

Degradation Green spaces arriving site Green spaces

Agriculture Soil

Agriculture Soil

Degradation depart site 1st Annual Urban soil symposium 12/09/2016

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Technosols: definition Soils containing a rate of artificial materials greater than 20% of the volume in 100 cm thick. (WRB, 2014)

The result of voluntary action of building a "soil" by using technogenic materials considered as waste, for growing vegetation. (Baize et Girard, 2009)

Constructed Technosols 1st Annual Urban soil symposium 12/09/2016

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Why Technosols are important? A solution for soil degradation (Séré et al., 2008)

Urban agriculture

Constructed Technosols

Green spaces

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Influence of organic matter

Excavated Deep Horizons EDH< 4mm

2 % clay 43 % carbonates 8.2 pH 2.7 g cm-3 PD 1.3 g cm-3 BD 0.38 % Corg

13 % C/N 8 pH 2 g cm-3 PD 0.6 g cm-3 BD 21.41 % Corg

Green Waste Compost OM < 4mm

Mixed by concrete mixer (10 min) 0% 10% 20% 30% 40% 50% -> 6 different volumetric proportions of compost = 6 Technosols 1 L in each microcosm 1st Annual Urban soil symposium 12/09/2016

n = 24

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Influence of organisms 0.5 g individual

0.17 g grains

Earthworms (endogeic) 4 treatments: 1) Soil only (C) 2) with Earthworms (E) 3) with Plants (P) 4) with Earthworms and Plants (EP) 1st Annual Urban soil symposium 12/09/2016

Plants (Lolium perenne)

X

6 % OM

X

4 rep. = 96 pots

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Incubation in controled conditions

- 21 weeks in a climate chamber - Photoperiod: 12 h - Luminosity: 500±20 µmol photons.m-2.s-1, - Temperature: 22/20±0.2°C day/night respectively - Air humidity: 75±2% - Soil humidity: 80% of WHC 1st Annual Urban soil symposium 12/09/2016

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Objective Characterize the effect of the presence of earthworms and / or plants for different amounts of organic matter on: • the state of aggregation (fraction) • the organic carbon content for each fraction • aggregate stability

1st Annual Urban soil symposium 12/09/2016

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Size Morphological distribution of soil aggregates size

More than 5 mm, between 3 and 5 mm, between 3 and 2 mm, and less than 2 mm

origin

Earthworm casts, rhizosphere aggregates, physiochemical and microbial aggregates and the last group is both non-aggregated soil and aggregates smaller than 2 mm (Velasquez et al., 2007)

1st Annual Urban soil symposium 12/09/2016

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Size Morphological distribution of soil aggregates size

origin

More than 5 mm, between 3 and 5 mm, between 3 and 2 mm, and less than 2 mm Earthworm casts, rhizosphere aggregates, physiochemical and microbial aggregates and the last group is both non-aggregated soil and aggregates smaller than 2 mm (Velasquez et al., 2007)

Mineral and organic carbon quantification of different sizes of aggregates

Aggregate stability determined by the method ISO/CD 10930 (Le Bissonnais, 1996)

1st Annual Urban soil symposium 12/09/2016

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weight distri

weight distributio

20

5

15

50

c 40

40

30

weight distribution %

Effect of organisms and OM on sieving weight distribution of total10 d 0 c 0 10 20 30 40 50 macro aggregates % 0 70

15

30

> 5000 µm

10

10 3150-5000 5

25 60

20 50

15

c 5

0

c

0

0 0

40

5

a

30

Control

b

20

20

40

50

GWC ratioControl V%

10

30

10

40 50ratio V% GWC 0 20 GWC ratio10V%d Control Control Earthworm 10 20 30 40 10 50 d 0 10 20 30 40 50 Earthworm Earthworm Plant GWC ratio V%Control GWC ratio V% 20 30

1030 20

0

µm

0

Earthworm

Earthworm

Plant

10

20

30

40

Worm and Earthworm andPlant plant

0 0

10

20

30

40

50

0

10

20

30

40

50

30

40

50

30

weight distribution %

25

2000-3150 µm

70

< 2000µm

60

20

50

15

40

10

30 20

5

c

10

d

0 0

10

20

30

40

50

0

GWC ratio V% Control

1st Annual Urban soil symposium 12/09/2016

Earthworm

10

20

GWC ratio V% Plant

50

Plant Earthworm and plant Plant GWC ratio V%

Earthworm and plant

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Effects of organisms and organic matter on the weight distribution of total macro aggregates % of Technosols RDA analysis Total variance explained by the compost and organisms: 60 % (p = 0.005)

OM: 5 % (p = 0.08)

1st Annual Urban soil symposium 12/09/2016

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Effects of organisms and organic matter on the weight distribution of total macro aggregates % of Technosols RDA analysis Total variance explained by the compost and organisms: 60 % (p = 0.005)

Organisms: 50 % (p = 0.005)

1st Annual Urban soil symposium 12/09/2016

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Effects of organisms and organic matter on the weight distribution of total macro aggregates % of Technosols RDA analysis Total variance explained by the compost and organisms: 60 % (p = 0.005)

Compost: 5 % (p = 0.08)

Organisms: 50 % (p = 0.005)

joint effect: 5 %

Biotic Effects > Abiotic Effects 1st Annual Urban soil symposium 12/09/2016

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weight distri

weight distributio

20

5

15

c 40

50

c

0

10

80

10

80

> 5000 µm

60

5

c

5

0

c

0

0 40

20

10

20

20

30

40

50

30

Control

0 80

2000 - 3150 µm

60

60

40

40

20

20

0

10

20

40

50

0

Earthworm

Earthworm

Plant

10

20

30

40

30

40

50

10

20

30

40

50

Worm and Earthworm andPlant plant

30

40

50

< 2000 µm

0

GWC V% GWC ratio V% Control Earthworm Plant

1st Annual Urban soil symposium 12/09/2016

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20

GWC V% Earthworm and plant

50

Plant Earthworm and plant Plant GWC ratio V%

0

0

50

40 50ratio V% GWC 0 20 GWC ratio10V%d Control Control Earthworm 10 20 30 40 10 50 d 0 10 20 30 40 50 Earthworm Earthworm Plant GWC ratio V%Control GWC ratio V%

0 10

d

20 30

1030 20

0

GWC ratioControl V%

20

0

80

0

40

30

40

10

3150 - 5000 µm

60

0

SOC distribution in aggregates

Distribution of Corg in the aggregates %

SOC distribution in aggregates

0 10carbon 20 30 40 Effect of organisms and OM on the distribution of organic 0 15

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Effect of organisms and OM on the distribution of organic carbon RDA analysis Total variance explained by the compost and organisms: 76 % (p = 0.005)

compost: 28 % (p = 0.001)

Organisms: 22 % (p = 0.005)

joint effect: 26 %

1st Annual Urban soil symposium 12/09/2016

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Structural stability It is the ability of a soil to retain its spatial organization (solid / void / aggregates) when exposed to various stresses (Cosentino, 2006) Fast wetting Slow wetting

1st Annual Urban soil symposium 12/09/2016

Mechanical disaggregation

20

10

30

30

0

020 1030 2040 3050 40 50

weight distri

0

weight distri

20

20

50

0

50

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020 1030 2040 3050 40

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Effects of organic matter and organisms on the structural stability 70 70

2,5 2,0 1,5

15 10 5

20

0

10

20

3,5 0

60 a wetting Fast

20 10

20 50

30

5

c

20

40

4025

25

10

04050 1050

bMechanical disaggregation

b 0 30

40 0 5010

0 3,5 20 30

040

1050

20

30

40

50

30

3,0

15

0

0

0,5

20 30

c

1,0

a

weight distribution %

3,0

20

30

60

weight distribution %

weight distribution %

weight distribution %

30

Slow capillary wetting 3,5

40

25

25

diameter MWD (mm) Mean width MWD(mm)

40

2,5 20

30

3020

2,0 15

15

20

20

1,5 10

1,0

10

10

5

5

d

d

10

70

3,070

60

60 2,5

50

50 2,0

40

40

30

1,5 30

20

1,020

c c 10 d 0,530 0,510 40 d 50 0 10 20 40 50 0 10 20 30 0 30 10 40 20 5030 40 50 0 10 20 30 40 50 0 010 0 20 30 40 50 0

10 20 30 40 20 30 40 50 Compost ratio V%

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GWC Compost ratio ratio V% GWC ratio V% Compost ratio V% Compost ratio V% GWCV% ratio V%ratio V%GWCCompost GWC ratio V% GWC ratioratio V% V% GWC ratio V% Compost ratio V%

0

10

20

30

040

1050

20

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40 0 50 10

20

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040

1050

GWC ratio V%

Earthworm and plant Earthworm Plant Plant Control Earthworm Control Worm andand Plant Earthworm Plant Earthworm plant Earthworm Earthworm and plantplant Earthworm Plantand Earthworm Plant Control ControlEarthworm Earthworm and plant Plant

Control Control

1st Annual Urban soil symposium 12/09/2016

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Conclusion The effect of organic matter and organisms on the aggregation and structural stability • The effect of organisms on aggregation and structural stability is greater than the effect of the compost. • Plants improve structural stability observed by slow wetting especially as organic matter ratio increases. • The simultaneous presence of worms and plants maximize the structural stability for all types of tests (slow wetting, fast and mechanical weathering). The association of these organizations is most beneficial in terms of resistance to erosion.

1st Annual Urban soil symposium 12/09/2016

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Effects of organisms and organic matter on the physical parameters of Technosols RDA analysis Total variance explained by the compost and organisms: 86 % (p = 0.005)

OM: 4 % (p < 0.05)

1st Annual Urban soil symposium 12/09/2016

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Effects of organisms and organic matter on the physical parameters of Technosols RDA analysis Total variance explained by the compost and organisms: 86 % (p = 0.005)

Organisms: 77 % (p = 0.005)

1st Annual Urban soil symposium 12/09/2016

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Effects of organisms and organic matter on the physical parameters of Technosols RDA analysis Total variance explained by the compost and organisms: 86 % (p = 0.005)

compost: 5 % (p = 0.08)

Organisms: 50 % (p = 0.005)

joint effect: 5 %

Biotic Effects > Abiotic Effects 1st Annual Urban soil symposium 12/09/2016

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Thank you for your attention

1st Annual Urban soil symposium 12/09/2016