SOC and biodiversity dynamics under DMC systems: Enhancing soil potentialities and production of...
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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)
THE 4TH INTERNATIONAL CONSERVATION AGRICULTURE CONFERENCE IN SOUTHEAST ASIA