African Agriculture Inc., an investment company based in a ninth-floor Regus co-working space on Park Avenue in New York, is growing 300 hectares (740 acres) of emerald-green alfalfa east of Saint-Louis inside a desert nature preserve called the Ndiael. The farm draws its water from nearby Lake Guiers, which is fed by a canal from the river. The only freshwater reserve in Senegal, the lake supplies half the water for Dakar, Senegal’s capital.