Basic and Applied Ecology (Mar 2023)
Sahelian smallholders’ varietal mixtures reconcile yield and agrobiodiversity conservation
Abstract
In the current setting, marked by the major challenges of growing food demand and climate change impacts, the ability of sub-Saharan agriculture to meet population needs depends on the resilience and adaptation capacity of this system. Using agrobiodiversity to promote agricultural sustainability is a strategy that has garnered much attention lately. Research suggests that mixing species or varieties within crop fields could increase the yield and/or stability. This mixing is also geared towards the conservation of crop diversity while ensuring that the various associated products and services will be available at the farm level.Few recent research studies have highlighted the benefits of varietal mixtures for Africa. This lack of research is a concern, given that this continent is considered to be highly vulnerable to climate change. This study was carried out to test whether plots with varietal mixtures would outperform monovarietal plots in terms of yield and pathogen regulation under smallholder farming conditions in Senegal. Together with farmers, we conducted 30 experiments in which mixtures of early- and late-flowering pearl millet landraces were grown in these farmers’ fields, while monitoring their low input management. We noted a significant positive effect of varietal mixtures on grain yield (mean gain of 63 ± 31.5 kg ha−1 for mixture plots, p = 0.046) with a relative yield total (RYT) averaging 1.87 ± 0.94. Both early- and late-flowering landraces benefited from mixtures, with a greater impact on late-flowering landraces. Higher fertility in terms of the seed number, percentage of fertile tillers and number of panicles per tiller, was documented in mixture plots. We did not find a significant effect of mixture on fodder, striga or weed infestation.In water and nutrient resource limiting conditions, such as in Sahelian agroecosystems, growing mixtures of early- and late-flowering landraces appeared to be an efficient way to increase productivity while ensuring agrobiodiversity conservation. Perhaps even more importantly, mixtures allowed farmers to harvest multiple products with different uses in an agrosocioecosystem context with constantly increasing land pressure.
