Evaluation of yield gap and production factors in cocoa systems along a climatic gradient in Ghana

Abstract

This study assessed the cocoa yield gap and production factors in three sites along a cocoa climate suitability (rainfall) gradient in the cocoa belt of Ghana.

Full text

Outliers
Dry Mid Wet
Location
-1
0
1
2
3
4
5
6
7
Number of non cocoa plots
Issaka Abdulai1, Laurence Jassogne2, Sander Muilerman2, Richard Asare2, Peter Läderach3, Piet Van Asten2, Sophie Graefe4, Philippe Vaast5
1Crop Production Systems in the Tropics, Georg-August-Universität Göttingen, 2International Institute of Tropical Agriculture (IITA), Ghana/Uganda, 3Centro Internacional de
Agricultura Tropical (CIAT), Nicaragua, 4Tropical Silviculture and Forest Ecology, Georg-August-Universität Göttingen, 5CIRAD, Montpellier, France and ICRAF, Nairobi, Kenya
Acknowledgements
The authors thank the farmers for their warm reception for
both interviews and on-farm visits. BMZ is acknowledged for
funding the project.
Contact: iabdula@gwdg.de
current2050
Table 1 Current climate per location.
Outliers
Dry Mid Wet
Location
0
200
400
600
800
1000
1200
1400
1600
Cocoa yield (kgha-1year-1)
Location
Attainable
yield
(kg ha-1yr-1)
Yield
gap
(kg ha
-1yr-1
)
Percentage
yield gap
(%)
Factors of production
Spearman
R
Fungicide usage (Sachets/ha)
0.375
% TOTAL soil N
0.290
% Base Sat.
0.270
Dry
975
686.9
70.5
Training
days yr-1
0.268
Soil Ca
(cmol kg-1)
0.262
Soil
P/cmol kg-1
0.260
E.C.E.C /
cmol kg-1
0.257
Pesticide usage (
ltrs ha-1)
0.240
% Soil CARBON
0.236
%
Soil organic matter
0.236
Soil pH
0.235
Cocoa density (trees
ha-1)
0.223
Inorganic fertilizer (bags
ha-1)
0.208
Exch. A (
Al+H) cmol kg-1
-0.229
Shade tree
species ha-1
0.272
% Clay in soil
0.230
Mid
1386.703
673.9
48.6
Average cocoa
dbh (cm)
-0.225
% Base Sat.
-0.227
Soil pH
-0.228
Plot area
ha-1
-0.306
Mistletoe severity
(%)
-0.423
Dieback severity
(%)
-0.424
SPU planting material
0.391
Wet 1483.549 644.4 43.4
Exch. A (
Al+H) cmol kg-1
-0.246
% Clay in soil
-0.259
Farmer select planting material
-0.344
Location
Temp.
◦C
Rainfall mm
Dry
27
700
- 1200
Mid
25
1250
- 1750
Wet
26
1300
- 2000
Cocoa income
Non cocoa income
Dry Mid Wet
Location
0
2
4
6
8
10
12
Proportion of income
Shade tree
parameters
Location
Mean Dry Mid
Wet
Shade cover (%)
27.00
13.09
17.66
Trees ha-1 49 23 34
Species ha-1
22 11 16
0
10
20
30
40
50
60
70
80
Timber Fruit trees Yam stake Soil fertility Others
Percentage of total trees (%)
Primary function of shade trees
Dry
Mid
Wet
a b
Table 3 Shade tree characteristics
along the gradient.
Fig.4 Additional functions of shade trees.
Fig.3 (a) Cocoa and non cocoa income, and (b) number of non cocoa plots per
location.
•Three sites along a latitudinal gradient in Ghana
(Fig. 1)
•Surveys were carried out with 50 farmers per
location.
• Farmers were interviewed about management
practices.
•On-farm inventories for assessment of shade
trees, soil and foliar sampling, and pests and
disease monitoring.
•Cocoa yield gaps were calculated by estimating
the difference between attainable and observed
yield per location.
•Contribution of production factors to yield gap
(i.e. soil fertility, management, pest and diseases)
were analyzed.
Evaluation of yield gap and production factors in cocoa
systems along a climatic gradient in Ghana
Background
•Factors limiting cocoa production include pests and diseases, low soil fertility, poor
management practices and above all climate change.
•The cocoa growing region of Ghana is predicted to experience increased
temperatures, resulting in higher evapotranspiration rates. Erratic rainfall patterns
and longer dry seasons may cause heat and water stress.
•Sustainable intensification through climate smart agriculture (CSA) has been
identified as the way forward, which requires site-specific adaptation options.
•This study aims to identify variation of yield gaps in cocoa production, as well as
constraints and opportunities for CSA along a climatic gradient in the coca belt of
Ghana.
Materials and Methods
Fig. 1 Climate suitability of cocoa in
Ghana.
•Mean cocoa yields are 288.1, 712.8 and 839.2 kg ha-1 yr-1 for the dry, mid and
wet region (Fig. 2).
•Cocoa yield gaps are 70.5, 48.6 and 43.4% for the dry, mid and wet region
(Table 2).
•Soil fertility and management practices (input usage) present the major limiting
factors in the dry region, while the mid and wet regions are rather limited by soil
nutrients (Table 2).
•Current adaptations at farm level are through income diversification (Fig.3a&b),
and at plot level through shade trees (Fig.4, Table 3).
Results
•Cocoa yield follows climate suitability.
•High yield gaps at the less suitable areas are a result of the combined effect of
climate, management (low intensification) and missing institutional support.
•Farmers diversified their livelihoods (non cocoa income) in less suitable areas.
•Plot level adaptations (e.g. use of shade and fruit trees for diversified products) are
evident in the northernmost site.
•Improved current adaptations in the dry region can be adopted for the mid and wet
regions, while there is need for transformational adaptation in the dry areas.
Table 2 Yield gap and important limiting factors along a latitudinal gradient in Ghana.
Fig. 2 Cocoa yields of the 2012/13 season.
Conclusions
Tropentag 2015