Vulnerability of Rice and Maize Yields to Climate Variability in the Sudano-Sahelian Zone of The Gambia: Drivers and Adaptation Options

Abstract

Staple food crops are considered as the driving force for household food security and source of livelihood activities for many developing nations. Farming practices face many challenges due to the adverse impacts of climate change and variability in the 21st century. This study assessed the extent to which maize (Zea mays L.) and rice (Oryza sativa L.) yields are vulnerable to climate variability in the Lower River Region of The Gambia. The influence of climate variability was assessed using the ordinary least square regression and heteroscedasticity methods. The potential soil physical and chemical properties were estimated using diagnostic soil survey of simple random sampling approach. Data were collected from 30 upland maize fields and 30 swamp rice fields. Crop yields were projected using two Global Circulation Model (GCM) models that performed best in the study area: CSIRO-RCP4.5 and NOAA-RCP4.5. Climate change adaptation options were assessed through semi-structured questionnaires with 180 selected households in eighteen communities using multistage sampling techniques. The results of climate influence on crop yields showed that CO2 and rainfall unfavourably affect rice yield and were statistically significant. Maximum and minimum temperature negatively affect yield but not statistically significant at (P < 0.05). The results further revealed that CO2, maximum temperature and sunshine duration adversely affect maize yield and statistically significant whilst rainfall and minimum temperature negatively affect maize yield but not significant at (P < 0.05). Soil survey results indicated that swamp rice ecologies had high percentage of NPK (N 0.07 %, P 0.0184 % and K 0.04 %) than percentage NPK contents in the maize fields (N 0.06 %, P 0.018 % and K 0.01 %). Soil pH is generally low and ranges from (4.6 to 4.7). The electrical conductivity of the soils for rice and maize fields are generally high (4.8 dS/m) indicating salt-affected soils. It is projected that, crop yields showed the percentage mean yield gain for maize iv under NOAA-RCP4.5 by 12 % and 41 % but most importantly CSIRO-RCP4.5 by 17 %, 31 %, and 48 % respectively, as the period gets close to mid-century compared to mean rice yield losses of -19 % and -23 % under NOAA-RCP4.5 scenario. The results showed that the majority (72 %) of farmers’ use drought-tolerant crop varieties with 67 % adapting to changing planting date. Majority (64 %) of farmers were forced to fallow their lands with 40 % of farmers practising petty trading and 47 % depending on temporal migration as a coping mechanism. It is concluded that rice and maize yield were vulnerable to climate variability coupled with fragile soil conditions. The future projection of yields will be inadequate to feed the growing population in the Lower River Region of The Gambia. There is a need for more adaptation strategies that are compatible with the local condition that can strengthen the resilience of households to cope with climate variability. Therefore, climate change adaptation policy should include local knowledge as a bottom-up approach to enhance their sustainability at the local level.