Climate Variability Incidence on Cassava Production in Bamenda II Sub-Division, Cameroon

Abstract

This study examined climate variability and its implications for cassava production in Bamenda II Sub-Division, Cameroon, with specific attention to the communities of Mbatu, Chomba, and Nsongwa. The analysis was based on meteorological records for 1981–2024 from the Bamenda Meteorological Station, supplemented by ERA5 reanalysis data from the World Bank Climate Change Knowledge Portal and published studies for the Bamenda Highlands. Rainfall variability was assessed using descriptive statistics, trend analysis, and the Standardised Precipitation Index (SPI). Cassava yield trends for the Northwest Region were obtained from MINADER and FAOSTAT for the period 2000–2024, and their relationship with rainfall and SPI was examined using Pearson correlation analysis. The results revealed a unimodal rainfall regime, with the productive rainy season extending from March to October and rainfall peaking in July at 402.78 mm. June to September accounts for approximately 74% of mean annual rainfall. Inter-annual SPI values showed alternating wet and dry years, with a weak overall drying tendency (y = -0.0016x + 0.0353; R2 = 0.0004) across the 44-year study period. Decadal analysis indicated that 1992–2002 was the only mildly wet period, while 1981–1991, 2003–2013, and 2014–2024 were characterised by mild dryness. The most recent period, 2014–2024, recorded the highest inter-annual variability (CV = 7.02%; SD = 12.48 mm), with severe negative SPI anomalies in 2020–2021 (SPI approaching -2.0). Mean annual temperature increased at an estimated rate of +0.3°C per decade between 1981 and 2024, consistent with regional trends. Northwest Region cassava yields ranged from 8.2 t/ha in 2000 to 11.6 t/ha in 2024, with a moderate positive correlation with annual rainfall (r = 0.61, p < 0.05) and a significant negative correlation with SPI anomalies below -1.0. Rainfall fluctuations affected cassava establishment, tuber formation, and harvest reliability, particularly where farmers depend on rain-fed production systems. The adaptation responses identified include adjusted planting dates, intercropping, mulching, crop diversification, and limited use of improved varieties (29–34% adoption rate). The study highlights the need for improved climate information services, stronger extension support, and wider access to drought-tolerant cassava varieties in Bamenda II Sub-Division.