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)
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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 %
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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
20
020 1030 2040 3050 40
10
15
15
10
10
5
5
50
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%
50
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
30
40 0 50 10
20
30
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