Figure 1: Map of West Africa, showing Ghana and Navrongo

Agriculture in Navrongo, Ghana (Figure 1), is predominantly characterized by low-input rain-fed smallholder farming shallow soils that are also poor in fertility. The dominant cropping system is cereal–legume based, with the main crops being sorghum, maize, millet, peanut, and cowpea.

Livestock also plays an important role in the farming system, serving as draught power as well as manure source for soil amendment. Crop residues are important feed stocks for the livestock.

The current agricultural system, with less than 50 kg/ha nitrogen application rate to cereals leads to relatively low yields of less than 2000 kg/ha. The legumes do not receive fertilizer application and yield about 1000 kg/ha.

The reliance on rainfall and the natural environment for agriculture production at Navrongo presents several challenges for future crop productivity. The combination of projected rising temperatures for West Africa by 2050s and the shifts in seasonal rainfall distribution implies that the current agriculture systems may be unsuitable for future.

Temperature increases depend on emission scenarios. High emission scenarios would result in a 1.0-2.5 C by the 2050s (Figure 2, left). Increasing temperatures would increase evaporative demand and higher soil desiccation.

Though the direction of change in rainfall is more uncertain (Figure 2, right), the projections indicate drier median conditions in the west (up to a 20% decline) and slightly wetter conditions in the east (up to 10% increase). Increasing late rainfall would lead to floods during crop maturity periods and adversely impact yields. Generally, CO2 concentration is expected to reach 491 and 571 ppm depending on emission scenario by 2050 from the current level of 399 ppm.

Figure 2:  Temperature (left) and rainfall (right) projections for West Africa
 

Current System

The implementation of current agricultural system (described above) under future climate conditions would lead to a change of between 2 and -17% (Figure 3). On the other hand, sorghum yields would largely be unaffected by climate change, apparently due to its relatively higher tolerance to higher temperatures and drought stress. Peanut, unlike the cereals will benefit from climate change due to projected CO2 fertilization.

Figure 3:  Climate change impact on crops at Navrongo, Ghana under current production system for different emission scenarios.
 

Future System

A future agricultural production system at Navrongo would comprise of a combination of use of improved seeds, improved planting density and fertilizer application. Apart, it is expected that socio-economic, institutional as well as biophysical and technology would improve the overall productivity. Under this future system, climate change impact on maize would still be negative compared to sorghum (Figure 4). In both cases, however, the impacts would be more severe than compared with current production system.  Peanut would continue to be positively impacted by climate change. The magnitude of impact, however, is reduced under high emission scenario.

Figure 4:  Climate change impact on crops at Navrongo, Ghana under future production system for different emission scenarios.
 

The practice of the current agricultural production system under future climate conditions would result in between 48 and 59% of households becoming vulnerable to climate change. This translates into a reduction in net farm returns and up to 7% increase in poverty. 

When future agricultural production systems is adopted, the future socio-economic, institutional, biophysical and technological changes would result in reduced vulnerability to climate change to between 30 and 47% and also reduce poverty by up to 11%.

Agricultural systems will develop irrespective of climate change in response to increasing productivity. The type of growth trajectory desired would inform the development pathways that would be pursued by Ghana. In this case, two Representative Agricultural Pathways (RAPs) were co-designed with stakeholders, shown in Table 1: (i) sustainable development pathway (Green Road), and (ii) the other fossil fuel-based high emission development (Grey Road).

Table 1: Main features of the two Representative Agricultural Pathways (RAPs)

Adaptation packages

One adaptation package was tested for the future climate. This included the use of improved seeds with heat tolerance of crops (maize, sorghum and peanut). Also, it included improved farmer extension services and education as well as government policies on input subsidies to lead to high uptake by farmers.

Figure 5: Impacts of adaptation on crops at Navrongo, Ghana, under future production system for different emission scenarios.

Within the context of AgMIP a series of stakeholder engagements were organized in Ghana using the Navrongo crop production as the base study. The main focus was to build the capacity of stakeholders with regard to climate change impact on crop production for different emission scenarios and socio-economic development pathways. Stakeholders were drawn from the Environmental Protection Agency (EPA), CCAFS, Research, Academia, the Ministry of Food and Agriculture (MoFA), and the National Development Planning Commission (NDPC). Input from the stakeholders improved the RAPS process, and the development of proposed policies to address the climate change impacts on agriculture.

Stakeholder engagement with National Development Planning Commission (left) and CIWARA engagement with stakeholders in Accra (right)

A number of lessons were learned from the engagements with stakeholders regarding the outcomes predicted by AgMIP methodology.

• First, the AgMIP methodology is new to most stakeholders. Even scientists from Soil and Crop Research Institutes are unfamiliar with the AgMIP concepts. Some capacity training is required to improve the communication on AgMIP

• Second, with respect to policy formulation, stakeholders from the NDPC could not understand why AgMIP output should rank the need for fertilizer application under current climate over improved seeds. In other words, the debate centers on whether management impacts can outweigh the use of improved seeds.

• Third, the communication of AgMIP output to farmers remains a big challenge. Though policy formulation is the more direct target of models such as AgMIP, outcomes must also be expressed in a language easily comprehensible by end-users.  

• There is the need for constant interactions among stakeholders and training on climate change impact must be more regular.

• In general, current capacity of stakeholders in the fields of agricultural systems analysis and modelling approaches is very weak.