SOC and biodiversity dynamics under DMC systems: Enhancing soil potentialities and

production of ecosystem services

Examples from Laos and Brazil

F. Tivet (CIRAD), H. Tran Quoc (CIRAD), C. Khamxaykhay (DALAM/NCAC), JCM Sá (UEPG), P. Lienhard (CIRAD), J. Boyer (CIRAD), P. Tantachasatid (Kasetsart), K. Panyasiri (MAF), S.

Boulakia (CIRAD), L. Hok (RUA), R. Kong (GDA), A. Khamhoung (DALaM), L. Séguy (Agroecoriz)

THE 4TH INTERNATIONAL CONSERVATION AGRICULTURE CONFERENCE IN SOUTHEAST ASIA

THE 4TH INTERNATIONAL CONSERVATION AGRICULTURE CONFERENCE IN SOUTHEAST ASIA

ObjectiveObjective

to evaluate for a range of no-till systems the changes on SOC, soil physical properties and biodiversity …

… as a tool to improve cropping systems design and adjustment

• Strong connection with Thai market• Intensive cash crops production (maize and cassava)• Plow-based tillage, pesticides, hybrid seeds and chemical fertilizers• Yields decrease drastically + increasing production costs• High environmental impacts

Southern Xayabury/Laos: context and drivers of changes

3,000 km2

Temporal changes in SOC stock (0-30 cm)

Shifting cultivation + ~15 years under CT

Native

SOC

Stoc

k (M

g C

ha-1

)

Conversion to agriculture

Temporal changes in SOC stock

80

120

160

0

40 140Mg C ha-1

t0

Since the conversion: ~ 50% decrease in SOC stock

60-82 Mg C ha-1

Native vegetation

Basic igneous rocks, gabbro, dolerite480 g clay kg-1

42-54 Mg C ha-1

80 Mg C ha-1 Unfolded sandstone and claystone380 g clay kg-1

Shifting cultivation and less intensive ploughing

THE 4TH INTERNATIONAL CONSERVATION AGRICULTURE CONFERENCE IN SOUTHEAST ASIA

3 cropping systemsMaize monoculture ( 5.0 Mg DM ha-1) Maize (5 to 6) / Rice bean

(3 to 5)Maize (5 to 6) + B. ruziziensis (4 to

6) / Rice bean (3 to 5)

44 fa

rmer

grou

ps

1630

hous

ehol

ds

2000

ha

180 h

a

Density and diversity of soil macrofaunaMain differences on earthworm, ants, termites, millipedes (Diplopoda), and beetle (Coleoptera)

From Boyer J. (CIRAD) and Tantachasatid P. (Kasetsart University)

THE 4TH INTERNATIONAL CONSERVATION AGRICULTURE CONFERENCE IN SOUTHEAST ASIA

CT-M NT-M

Infil

trat

ion

rat

e (c

m h

-1)

0

10

20

30

40

50

60

CT-MV NT-MV CT-MV NT-MV Ruzi

Infiltration rate (cm h-1, 0-30 cm depth)

Maize monoculture ( 5.0 Mg DM ha-1) Maize (5 to 6) / Rice bean (3 to 5) B. ruziziensis

THE 4TH INTERNATIONAL CONSERVATION AGRICULTURE CONFERENCE IN SOUTHEAST ASIA

22

44

20

4753

25

55

Changes in soil physical propertiesMaize Maize - ricebean M + ruzi - ricebean M + ruzi - ricebean

Total water retention (mm ha-1, 30 cm depth)CT 127 118 114 129NT 147 145 126 136

Gain +20 mm +27 mm +12 mm +17 mm

% of macroaggregates > 8 mm (0-10 cm, wet sieving)CT 16 12 18 16NT 47 38 53 57

THE 4TH INTERNATIONAL CONSERVATION AGRICULTURE CONFERENCE IN SOUTHEAST ASIA

CT-M

NT-MRV

Disruptive effect of ploughing SOC losses

Enhancing macroaggregation SOC protection and accumulation

Gentle slope < 5% Flat land Steep slope > 15%

Changes in SOC (0-30 cm, 6-yrs period)

Soil organic C (g kg-1)

10 15 20 25 30

CT-MV, 81.8 Mg C ha-1

NT-MV, 83.0 Mg C ha-1

Soil organic C (g kg-1)

10 12 14 16 18 20 22

CT-MV, 69.8 Mg C ha-1 NT-MRV, 72.1 Mg C ha-1

Soil organic C (g kg-1)

10 15 20 25 30

So

il la

yers

(cm

)

0-5

5-10

10-20

20-30

CT-M, 73.0 Mg C ha-1

NT-M, 79.3 Mg C ha-1

0-1010-20

20-30

SO

C (

Mg

ha

-1)

05

101520253035

0-1010-20

20-30

SO

C (

Mg

ha

-1)

05

101520253035

0-1010-20

20-30

SO

C (

Mg

ha

-1)

0

5

10

15

20

25

30

Soil organic C (g kg-1)

10 15 20 25 30

CT-MV, 60.3 Mg C ha-1

NT-MRV, 82.4 Mg C ha-1

0-1010-20

20-30

SO

C (

Mg

ha

-1)

0

10

20

30

40

***

***

*

* ****

**

** ***

Mean ± Std. Error, n = 4

Eq. Soil-mass depth basis

DSOC: 0.2 to 3.7 Mg C ha-1 yr-1

THE 4TH INTERNATIONAL CONSERVATION AGRICULTURE CONFERENCE IN SOUTHEAST ASIA

What are the main gains (basaltic soils)?NT vs. CT 10,000 ha

Fauna Biomass (kg ha-1) + 128 +1,280 MgDiversity (taxa ha-1) +2.3Density (Ind m-2) +801

THE 4TH INTERNATIONAL CONSERVATION AGRICULTURE CONFERENCE IN SOUTHEAST ASIA

Infiltration rate (cm h-1) +26.3Total water retention (mm ha-1) +19 +190 m3

Aggregation (mean diameter, mm) +4.4

CEC (cmol ha-1, 30 cm depth) +0.5 to 8.7 cmol ha-1

+1.2 cmol ha-1 +12,000 cmol yr-1

SOC 0.2 to 3.7 Mg ha-1 yr-1

0.54 Mg C ha-1 yr-1 +5,400 Mg C yr-1

sorghum + Brachiaria + pigeon pea

Sunflower + Crotalaria

sorghum + Brachiaria + pigeon pea

Sum

mer

wet

Soybean of high productivity (>4.0 tons/ha)

Finger millet + Crotalaria

millet + Brachiaria ruziziensis

Win

ter h

ot a

nd d

ry

Maize + Brachiaria + pigeon pea

15 tons of biomass/ha

TROPICAL CERRADO REGIONFrom L. Séguy, S. Bouzinac and partners

SUBTROPICAL AGROECOSYSTEMS

Fazenda Agripastos, Manoel Henrique Pereira

Changes in C content in aggregate size classes

Land use Aggregate size classes (mm) C input

8-19 4-8 2-4 1-2 0.5-1 0.25-0.5 0.053-0.25C content (g C kg-1) Mg C ha-1 yr-1

TropicalNV 41.2 37.8 41.3 48.7 36.0 25.1 15.6 4.30CT 19.2 18.0 18.1 21.8 15.6 12.6 13.3 4.01NT 24.4 24.6 25.5 27.8 21.2 15.6 14.4 7.60

SubtropicalNV 82.1 75.9 73.6 71.6 76.0 76.0 69.2 -CT 35.3 34.6 33.4 32.5 32.7 32.7 32.5 3.07NT 48.4 48.2 49.1 47.5 49.5 50.2 51.7 4.15

SOC is more labile and less processed under NT than under CT, suggesting that spatial inaccessibility within aggregates plays a major role in enhancing SOC accumulation.

‘free’ and labile SOC: plant, fauna and microflora nutrition, and structural stability.

Tivet et al., 2013. Soil and tillage research, 126: 203-218.

THE 4TH INTERNATIONAL CONSERVATION AGRICULTURE CONFERENCE IN SOUTHEAST ASIA

8 yr

s29

yrs

THE 4TH INTERNATIONAL CONSERVATION AGRICULTURE CONFERENCE IN SOUTHEAST ASIA

SUBT

ROPI

CAL

AGRO

ECO

SYST

EM

… higher catabolic demand under NT

Bigger « engine » under NV but …

… different groups of bacteria and functions

(see Lienhard et al., 2013. ASD 33: 375-384)

Sá et al., 2014. Forthcoming

THE 4TH INTERNATIONAL CONSERVATION AGRICULTURE CONFERENCE IN SOUTHEAST ASIA

SUBT

ROPI

CAL

AGRO

ECO

SYST

EM

Sá et al., 2001. Soil Science Society of America Journal. 65: 1486 - 1499

+19.0 Mg C ha-1 and+ 1.91 Mg N ha-1 under NT22

Higher SOC and N stocks under NT

DSOC: 0.86 Mg C ha-1 yr-1

t115 years

continuous soybean

under CT

Native

t2

SOC

Stoc

k (M

g ha

-1)

71.4 Mg C ha-1

61.4 Mg C ha-1

Conversion to agriculture

Temporal changes in SOC stock

0

20

40

60

80

0

20

40

60

80

CT55.6

Mg ha-1

Forest75.7

Mg ha-1

8 years under CT or NT

NT systemsC input: 6.84 to

8.38 Mg C ha-1 yr-1t0

Temporal changes in SOC stocks (0-40 cm depth) - Tropical agroecosystem

Tivet et al., 2013. Geoderma. 209-210: 214-225.

Sá J.C.M., Séguy L., et al., 2013. Land Degradation & Development: DOI: 10.1002/ldr.2218.

DSOC: 0.7 to 2.0 Mg C ha-1 yr-1

Cambodia – Bos Knor station PhD. Lyda Hok (RUA), partnership GDA - CIRAD (PAMPA), North Carolina A&T

(SANREM) and UEPG (Brazil) 3 experiments (rice, soybean and cassava), randomized block design (60 plots of

300 m2) 4 cropping systems selected per experiment: SOC dynamics to 1-m depth + soil

microbial abundance and diversity

Soil biomass and diversity

Continuous fresh C flux (above +

rhizodeposition)

C cycling

Nutrients availability (N, P, S), pests management?

ConclusionsTHE 4TH INTERNATIONAL CONSERVATION AGRICULTURE CONFERENCE IN SOUTHEAST ASIA

Nutrient cyclingDynamicsAvailability N and P

Carbon dynamicsTurnoverStabilization

Soil structureAggregation

PorosityWater retention

Habitat provision

Pest management

Soil structureCEC

22

Thank for your attention

Rice direct seeded on Stylosanthes guianensis residues – Cambodia (PADAC – GDA)

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