Transcript PPT, 184 KB - global change SysTem for Analysis, Research

AGRONOMIC ADAPTATIONS TO
CLIMATE EXTREMES (AF23)
P. O. Aina1 and J. O. Adejuwon2
1Department of Soil Science;
2Department of Geography;
Obafemi Awolowo University, Ile-Ife. Nigeria
REGIONAL WORKSHOP ON
ASSESSMENTS OF IMPACTS AND
ADAPTATIONS TO CLIMATE CHANGE (AIACC)
DAKAR, SENEGAL. MAR 24-27, 2004
Presentation Focus
 INTRODUCTION
 STUDY METHODOLOGY & OBJECTIVES
 ECOLOGICAL ENVIRONMENT
 AGRICULTURAL SYSTEMS
 AGRONOMIC ADAPTATION STRATEGIES
 CONCLUSIONS
 LESSONS LEARNED, RESEARCH NEEDS &
PROPOSED APPROACH FOR FUTURE WORK
NIGERIA CASE STUDY
INTRODUCTION
 Climate change inevitable
 Increasing trend of climate extreme events
 Agriculture is vulnerable
 crop yield reductions; global food security
 Autonomous adaptation
 Planned adaptive strategies needed
 Study: assessment of agronomic adaptation
strategies in long-term yield response exps
in Nigeria
WEST AFRICA
Mauritania
Mali
Senegal
Guinea
Chad
Burkina Faso
Liberia Ghana
Ivory Coast
1000
Niger
0
Nigeria
Cameroon
1000
2000 Kilometers
NIGERIA ….
• Lat 4o and 14o N, Long 2o 45’ & 14o 30’E.
• landmass of 924,000 km2 & 110m people.
• diverse people, ecological regions, soils and
agricultural systems
• varied crop responses to climate impact and
adaptation strategies
Ecological Environment
•
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•
•
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Humid zone
annual rainfall >1500mm; growing season - 270 days.
biophysical constraints - low soil fertility, water erosion low resilience
to cultivation, poor drainage
Sub-humid zone
annual rainfall: 600-1500mm; growing period - 150-269 days.
constraints - vulnerable soils, erosion, water stress, poor rainfall
distribution and poor soil water retention capacity
Semi-Arid zone
annual rainfall 400-600mm & growing season - 75-149 days
constraints: wind erosion, low permeability, salinity, heat and water
stress.
Arid zone
annual rainfall 100-400mm <75 days growing period.
constraints: same for Semi-arid region
Agricultural Systems and Agricultural Potential
• shifting cultivation & rotational bush or
grass fallowing
• wide range of crop husbandry methods
• < 0.5% of the land under irrigation
• Small-holder, subsistence & rain fed
• low and unsustainable crop yields low input technology
biophysical constraints to crop production
Agronomic Adaptation Strategies
• crop diversification
• changes in planting date and timing of field
operations
• changes in crop growing conditions and crop
choices
• soil fertility management and erosion control
• tillage technology
• water management
Crop Diversification
mixed cropping or intercropping systems
Insurance against total crop failure -- range of maturities and climatic
tolerances due to diversity in genetic structure & compositions
Table 1: Effect of intercropping on crop yields, kg ha-1 (Aina, 1989)
Solo
Maize
Maize+Cowpea
% Yield
change
Humid
(Ibadan)
1850
1980
+7
Sub-humid
(Ile-Ife)
2100
2450
+17
Semi-arid
(Zaria)
1865
2050
+10
Arid
(ICRISAT)
1570
1754
+12
Region
Intercrop
Millet + g’nut
Changes in Planting Date
• adjusting to earlier (?) planting dates
• sensitive growth stages, extend the growing
season
• increases crop yields by between 20% and
40% - Udom and Adebitan (1998), Fakorede (1985), Fakorede
and Opeke (1985), Lal (1973) and Aina (1988)
(?) depends on the predictability of the
precipitation pattern.
Soil Fertility Management and Erosion Control
 Fertility -- adequate crop nutrition will enhance resilience
of agriculture to climate hazards
• Inorganic fertilizer application, manure amendment,
rotational cropping, adequate soil organic matter,
increase soil fertility, crop yields (by 50% -120%)
 erosion leads to rapid soil degradation, physical loss of
plants & soil productivity. Control Practices:
• Optimum plant population, residue mulching,
Agroforestry, changing land topography (land contouring,
terracing and construction of diversions and reservoirs and water storage )
Table 2.
Effect of fertilizer application on maize yields (kg ha-1) in
long-term experiments at locations in Nigeria (Aina, 1989)
Region
No Fertilizer
+ Fertilizer
Humid
890
1875
Sub-humid
755
2150
Semi-Arid
680
1585
Arid
430
850
Table 3: Soil loss and runoff from plots and watersheds
under different management systems (Aina, et al 1991)
.
Site
Management
Soil loss
t/ha/yr
Runoff
%
Samaru
Broadlands.
Semi-arid) Cropped ridges(down slope)
Cropped alternate tied ridges
Flat cultivation (bare)
Flat cultivation (arables)
21.0
19.6
5.7
3.8
4.0
20.4
27.9
18.2
25.2
20.3
Ibadan
(Humid)
232.6
0.20
0.66
2.25
42.1
2.4
18.1
18.8
Bare (runoff plots)
Mulched (runoff plots)
Terraced (watershed)
Unterraced (watershed)
.
Table 4. Crop yields soil and water conservation effects
of tied-ridges in the Semi-Arid region
Tillage method
Runoff
(%rainfall)
Erosion
(t ha-1)
Groundnut
Millet
Tied ridges
0.9
1.4
846
729
Sloping ridges
6.3
6.1
479
376
Ploughed ridges
12.2
13.2
658
352
Appropriate Tillage Technology
• adjustments in tillage for optimizing soil
temperature, moisture regimes and crop plant
establishment
• Conservation tillage - minimum, reduced tillage
and no-tillage technologies in combination with
crop residue mulch, Fallow and tillage practices
such as the planting of hedges
Table 5:
Effect of tillage on crop yield in the semi-arid region
Crop
Millet
Sorghum
Maize
Rice
Cotton
Groundnut
Yield
(kg ha-1)
Control With tillage
1558
1894
1691
2118
1893
2791
1164
2367
1322
1550
1259
1556
Change in
Yield (%)
+22
+25
+50
+103
+17
+24
TABLE 6: Effect of Cover (Stylosanthes) Crop on crop yield
Crop
Change in Yield
(%)
Region
Maize
+20 to +24%
Semi-Arid
Maize
+25 to +136%
Sub-humid
TABLE 7. Effect of cover-cropping on maize yields
Fallow species
Change in Yield (%)
P.phaseoloides
+70
P.palustris
+172
S.siamea
+70
L. leucocephala
+127
A. leptocarpa
+51
A.auriculiformis
+109
Improved Water Management
• less than 0.5% of the land in Nigeria
• Practices to reduce water stress -irrigation, reduced runoff and improved
water intake into soil
• extreme rainfall events -- drought/runoff,
flooding
• positive yield response (3-fold yield
increase) to irrigation even in humid area
rainfall variability
Table 8. Effect of supplementary irrigation on yields
of cowpea and maize (Fapohunda et al, 1984).
Crop
Irrigation (cm)
Cowpea Irrigation +Rain
Rain, No Irrigation
Maize
Irrigation +Rain
Rain, No Irrigation
Grain yield
(kg/ha)
1110
260
4825
4100
Table 9:
Changes (%) in crop yields in long-term experiments with and without
agronomic adaptation in different ecological regions in Nigeria
Maize
Cowpea
Sorghum
Cassava
w/o
Adaptation
+
Adaptation
w/o
Adaptation
+
Adaptation
w/o
Adaptation
+
Adaptation
w/o
Adaptation
+
Adaptation
-5
+2
-7
+5
+2
+8
-3
+8
SubHumid
(Ile-Ife)
-10
-5
-15
+2
+5
+10
-8
+5
SemiArid
(Zaria)
-18
-10
-20
-5
-2
+15
-10
+2
-25
-8
-22
-8
-10
+28
-15
+5
Region
Humid
(Ibadah)
Arid
(ICRISA)T
Climate-induced & bio-physical constraints
to crop production & adaptation measures
.
Inadequate or excessive moisture
• irrigation/drainage, mulching, short-cycle, drought resistant varieties
High Temperature
• mulching, irrigation
Soil
• tillage, fertilizer application, manure, liming, Erosion control
Crop
• high yielding, drought & disease resistant varieties, hybrid seeds
and pest control
Constraints to achieving full measure
of potential adaptation
• Low economic status to adopt tech innovations
• traditions dictate local practices
• poor knowledge of appropriate alternative adaptation
options
• poor predictability of future climate variability and
extreme events -- high level of uncertainties
Conclusions

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crop yield response to agronomic adaptation significant
wide gaps betn exp’l and farmers’ low yields
(little change (success) to existing agric systems)
resources for substantial change beyond farmer's means
low input technology, biophysical constraints & constraints to
adoption of adaptation measures.
drought most important abiotic stress limiting crop productivity
Low adaptive capacity -- high level of uncertainty; low
predictability
dearth of climate impact/adaptation studies & choice of
technological options in the region
need to enhance research capacities in developing countries
THANK YOU