In this paper, we present a controlled experiment to assess the impact of a switch to mechanized harvesting and mechanized threshing on smallholder rice farms in Nigeria. We measure how food losses and efficiency compare to manual harvesting and threshing practices, and evaluate the business case of mechanization for smallholder farmers, as well as the effect on total Greenhouse Gas emissions. Furthermore, we discuss observations on the socioeconomic impact of mechanization of farm operations, in particular on the role of women and youth. The experimental results show that mechanized harvesting and threshing not only significantly reduce losses and increase yields per hectare but also have a positive socio-economic impact. Mechanized harvesting and threshing are labor-saving, which lead in the case study to positive impacts, such as freeing up time of women during the busy harvest period for other activities and providing new opportunities for rural youth. A comparison of the costs farmers incur for on one hand manual harvesting and threshing and on the other hand mechanized harvesting and threshing show that mechanization of these activities constitutes a positive business case for farmers: a relatively small cost increase is offset by large by considerable yield (and therefore revenue) increases. Furthermore, when factoring in the fuel use of harvesting and threshing machinery, increased greenhouse gas emissions from mechanized practices are negligible compared to the food loss and waste induced greenhouse gas emissions that are avoided by reducing losses with the more efficient mechanized equipment.