A surge in global fertiliser prices is adding to worries about food security across sub-Saharan Africa, where small-scale farmers depend largely on imports — if they even use additional nutrients at all.

With prices tripling over the past 18 months, many farmers are considering whether to forgo purchases of fertilisers this year. That leaves a market long touted for its growth potential set to shrink by almost a third, according to Sebastian Nduva, programme manager at researcher group AfricaFertilizer.Org. That could potentially curb cereals output by 30-million tons, enough to feed 100-million people, he said.

“We are likely to see a scenario where yields are depressed and this will mean that either the government will have to readjust their budgets and import food, or there will be food shortages,” Nduva said...