Analysis of rainfall onset, cessation, and length of growing season in Northern Botswana: Implications to maize production

The analysis of onset and cessation of rainfall in Northen Botswana was carried out using daily meteorological data for five synoptic stations in the region namely, Kasane, Pandamatenga, Sua Pan, Maun, and Letlhakane. Applying Sivakumar's approach, the length of the growing season and the dates of rainfall onset and cessation were determined for the period from 1980–2020. According to the findings, the rainy season's start and end dates vary depending on the place and time of year. Pandamatenga had the earliest onset, whereas Letlhakane had the latest one. In the same way, the rains stopped between the 2nd of March in Pandamatenga, to 1st of April in Letlhakane. The duration of the maize growing season varied from day of year 228 to 257 at various places. The results indicate that Sua Pan had the shortest growth season and Kasane the longest. Changes in rainfall patterns that impacted the conditions required for maize flourish were identified by comparing multiple studies periods. The need for agricultural operations to adjust to the variable duration of the growing season is highlighted by this. For example, regions with a shorter growing season, such as Sua Pan, could require early maturity maize cultivars to guarantee that harvests can grow and mature before the end of rainy season. However, regions with longer seasons, such as Kaane and Pandamatenga, may need to use better water management techniques to cope with prolonged rain days. Overall, the results emphasize how important it is to adapt farming methods based on geographic location in order ensure food security, particularly in the modern era of shifting rainfall patterns.