Ethiopia: Improved crop varieties

Improved crop management, such as using improved seeds, applying fertiliser and shifting the planting dates, has high transformative potential for increasing yields. We used process-based and machine learning techniques to evaluate the effectiveness of different crop management strategies for farmers to adapt to climate change. Our analysis found that increasing soil organic carbon in Ethiopia by 20% has positive effects on crop suitability for all crops (increasing suitability between 2-6%, depending on scenario and crop), especially for maize and wheat (see Figure 2). Enhancing organic carbon produces the greatest suitability increases under RCP8.5 for maize, teff and sorghum (ca. 5% suitability increase) and also has positive mitigation effects. However, shifting the growing season forward by four weeks will result in detrimental effects on suitability of the four crops (wheat, teff, maize and sorghum), with suitability losses of up to 10 % projected, and can thus not be recommended as an adaptation strategy.

Figure 2: Evaluation of crop management adaptation strategies in reducing crop suitability.

Using the process-based crop model APSIM, we also evaluated the effect of increasing first basal and then top dressing NPK (Nitrogen, Phosphorous, Potassium) fertiliser on maize yield in Ethiopia for all zones (All) and for zones projected to experience yield losses (Loss). Fertiliser application among smallholders in Ethiopia is estimated to be of rather low intensity, some 30-40% of smallholder farmers apply fertiliser (Spielman, Mekonnen & Alemu, 2011). Applying fertiliser is one means for improving lower and more variable yields due to climate change impacts and can thus also be regarded as an adaptation strategy. Yet, increasing synthetic nitrogen fertiliser application will also lead to higher CO2 emissions, a thorough assessment of its usefulness for each specific case is thus needed. The results show that increasing basal fertiliser by 50% will increase yields by between 10 and 200% depending on the zone. At national level, an average increase of 56% for all modelled zones under current climatic conditions is projected (Figure 3). 

Figure 3: Evaluation of the effect of increasing basal and top dressing fertiliser on maize yields in Ethiopia for all zones and for zones with projected yield losses.

We also conducted a cost-benefit analysis on one specific crop management strategy, namely a shift in cultivation from maize to sorghum, following the future suitability projections. The analysis shows that in comparison to the no adaptation scenario, the crop switch (adaptation scenario) will be economically beneficial from the year 2041 on (see Figure 4). From then on, the crop switch has a positive return on investment. The following figure shows this development of the net present value (NPV) from 2020 to 2050.

Figure 4: Development of the net present value of switching from maize to sorghum cultivation in Gambela under future climate change and over time (in ETB).

The late break-even point suggests that switching from maize to sorghum cannot be recommended in the near future, but rather in the medium term, once climate change impacts on the crop sector in Ethiopia further materialise. 

Table 2 provides an overview on potential development co-benefits and maladaptive outcomes of improved crop management in Ethiopia.

In conclusion, improved crop management can generally be recommended for adaptation to climate change in Ethiopia, although some strategies require ex-ante evaluation. Shifting planting dates for instance is not necessarily beneficial, but applying more (organic) fertiliser and investing in improved seeds can generally bring about better yields and higher resilience.

References

  • Spielman, D. J., Mekonnen, D. K., and Alemu, D. (2011). Seed, Fertilizer and Agricultural Extension in Ethiopia. IFPRI, ESSP II Working Paper 20.

Ghana: Improved crop varieties

Smallholder farmers in the global South mostly use traditional crop varieties, which can be vulnerable to climate impacts such as droughts, floods or also diseases. In order to improve the resilience of crops to climatic shocks and to raise yields, improved crop varieties are bred from traditional varieties. The process of breeding is lengthy and costly, but once better varieties are released and used, they can substantially improve agricultural yields and resilience, depending on their specific characteristics. As such, breeding improved varieties is an institution-led approach, since it requires resources and time, which smallholder farmers most often do not have.

Improved crop varieties can offer a number of interesting development co-benefits, especially linked to increased agricultural production and income. However, they are expensive to develop:  a multitude of factors will determine prices of the seeds, such as demand, scale of adoption, and – for farmers – potential government subsidies

A number of improved crop varieties already exist or are being developed in Ghana, for instance for maize, rice, cassava and cocoa, with sought-after properties being drought resistance, flood resistance and achievement of high yields. Maize appears to be the focus of breeding efforts in Ghana, as several publications (e.g. Alhassan, Salifu & Adebanji, 2016; Danso-Abbeam et al., 2017) and the number of active breeders for maize (10 out of 26) confirm (Mabaya et al., 2017).

An analysis conducted using the biophysical crop model APSIM shows that improved maize varieties indeed hold large potential for increasing yields under climate change (Figure 3). However, the size of the effect and sometimes even direction depends on the location, with the impact in different districts in Ghana differing considerably. Compared to no adaptation and other agronomic adaptation measures such as applying manure or delaying the sowing date, a carefully selected improved variety may indeed have a larger impact on increasing maize yields.

Table 1: Impact of agronomic adaptation measures on maize yield under climate change for three districts in Ghana (average yield projection for 2050 compared to 2006 baseline).

Another analysis conducted with machine-learning based crop suitability models shows how generally the effect of agronomic adaptation strategies varies considerably across crops. While maize and cassava appear to benefit from many agronomic adaptation strategies under climate change, for sorghum this is much more the case under the high-emission climate scenario (RCP8.5) and for groundnut, none of the adaptation strategies proposed has a positive effect.

Figure 3: Projected effects of different adaptation options on crop suitability for cassava, groundnut, maize and sorghum under RCP2.6 and RCP8.5. The adaptation options analysed are: a two-week shift in the growing season (beige), a four-week shift in the growing season (red), increasing soil organic carbon by 10% (brown), a combination of shifting the growing season by two weeks and increasing soil organic carbon by 10% (grey) and a combination of shifting the growing season by four weeks and enhancing soil organic carbon by 10% (mint).

Agronomic adaptation strategies and the use of improved seeds should thus be carefully evaluated for each specific region, crop and climate impact scenario. Nonetheless, improved crop varieties are seen as a transformative tool for buffering climate impacts in Ghanaian agriculture. Breeding is costly and time intensive, but where improved varieties already exist, they can contribute importantly to a higher agricultural output.

References

  • Alhassan, A., Salifu, H., & Adebanji, A. O., (2016). Discriminant analysis of farmers’ adoption of improved maize varieties in Wa Municipality, Upper West Region of Ghana. SpringerPlus, 5(1).
  • Danso-Abbeam, G., Bosiako, J. A., Ehiakpor, D. S., & Mabe, F. N., (2017). Adoption of improved maize variety among farm households in the northern region of Ghana. Cogent Economics and Finance, 5(1), 1–14.
  • Mabaya, E., Adzivor, S. Y., Wobil, J., & Mugoya, M., (2017). Ghana Brief 2017 – The African Seed Access Index, (December).