Increasing crop yields under climate change scenarios in Nigeria

Climate change is projected to cause unprecedented levels of global change and it will alter the ways in which humans currently rely on getting essential resources such as food. Africa is considered to be the most vulnerable continent to this change, with many countries that have low economic stability and insecure food sources a change to the way resources can be accessed could be detrimental to the population. One such example of this is agriculture: with the population expected to continue to rise stable sources of food will be needed, but climate change is making the production of high crop yields more difficult. This research studied the impact climate change will have on crop yields in Nigeria under the RCP 4.5 and the RCP 8.5 emissions scenarios from 1986 to 2100 using the LPJ-GUESS model. It showed that the average crop yields in Nigeria for maize, sorghum, wheat and pulses are likely to increase; even more so under the RCP 8.5 scenario due to higher estimated CO2 fertilization effects. Different management strategies to increase this further were then modelled which illustrated that when cover crops, irrigation or additional nitrogen were used, crop yields increased further, where the latter management strategy was most effective. Of the different crops, maize and sorghum produced the highest yields and were most robust to climate change. In general, crop yields were highest in the north and lowest in the south of Nigeria, with the exception of pulse crops where the opposite was true. The different agroecological zones present in Nigeria also caused different management strategies to be more effective in different regions. Overall, this research highlights the importance of using management strategies to increase food production for Nigeria in the face of climate change. Key words Physical Geography, Agriculture, Climate Change, Crop Yields and Management StrategiesThere is clear and proven evidence that the Earth’s climate is warming, this has now been shown in many ways, but the clearest evidence comes from widespread and global thermometer records. These rises in temperature have huge impacts on an ecosystem level and even alter how plants grow. This research focusses on the latter, looking at how crop growth, and thus crop yield, will be affected by increasing temperatures, and also increasing levels of CO2. The area of study is Nigeria, which, along with other countries on the continent of Africa, will experience greater average temperature increases and thus more adverse climate affects. Furthermore, in Nigeria agriculture is not so industrialised like in other countries and farmers tend to grow food in order to feed their families – therefore they are more likely to be negatively impacted if climate reduces crop yields. Regardless of whether yields are increasing or decreasing, the population in Nigeria is rising and more food will be needed to feed that population. The second area of research focusses on finding the most efficient farming management strategy to do this. Given that policy changes have scope to impact the amount of CO2 emissions released into the climate, and therefore change the extent of climate warming which will occur, two different emissions scenarios were modelled: one which follows the idea that policy changes will result in less emissions being released and one which follows an every day scenario, where CO2 emissions continue to increase at the present day rate. What this study found is that, firstly, crop yields are increasing in Nigeria across both emissions scenarios. The time frame studied was 1986 to 2100, and the crop species studied were wheat, maize, sorghum, and pulses: all of which showed an increase in yields up to the year 2100. Three key management strategies were studied alongside a control scenario: the use of cover crops between seasons, using irrigation instead of just relying on rainfall, and adding extra nitrogen to the soil as fertiliser. All crop yields increased more when these were implemented than when none were used. However, Nigeria has different climates, categorised as agroecological zones, and therefore it has different quantities of rainy and dry days depending on the agroecological zone. Therefore, some strategies, such as additional nitrogen, are more effective in the East where it is cool and humid, whereas irrigation is more effective in the North where it is warm and dry. In general, crop yields were highest in the north and lowest in the south of Nigeria, with the exception of pulse crops where the opposite was true. Overall, however, across all climates in Nigeria, additional Nitrogen was repeatedly the most effective strategy to increase crop yields. This research highlights the importance of using management strategies to increase food production for Nigeria in the face of climate change. Key words Physical Geography, Agriculture, Climate Change, Crop Yields and Management Strategie