In semi arid areas such as the Sahelian zone of Africa, many oils have become severely degraded. One extreme form is the bare and crusted soil, which is virtually productively "dead". In Burkina Faso, farmers have responded by applying mulch to attract termites that then help to rehabilitate the soil. A research project shows the importance of termites in breaking up hardened soil and increasing water infiltration. The land became productive enough to farm within months.