yam cultivation are practiced along the banks of the Sanaga in the Upper Sanaga division. Groundnuts, maize and other cereals are common in the province's less humid north, and manioc grows throughout. Sustenance farmers first clear small patches of forest. They remove trees with traditional tools such as axes or machetes during the dry season and burn the resulting brush. Farmers take care to protect trees bearing edible fruit, such as mangoes, plums, and pears, though fires sometimes grow out of control and prevent this. Farmers then plant seeds after the first rains: spices and vegetables closer to the house, plantains and tubers in larger plots farther into the bush. Villagers traditionally group their farms together as protection against animals and harvest their crops at the beginning of the dry season. Such slash-and-burn agriculture is adequate for the needs of small villages away from larger urban centres. Soil is exhausted quickly, necessitating the change of fields every two or three years. The soil can remain infertile for as much as ten years. However, when settlements are sparse, this presents little problem. As one of Cameroon's most populous areas, however, soil exhaustion has become an increasingly troublesome problem for the Centre in recent years. To combat this, MIDEVIV, the Food Development Authority, sets up growing zones around major towns, especially Yaoundé, for the growing of bananas, cocoyams, plantains, and other necessities. Plantation agriculture This region is one of Cameroon's most important cash-crop zones due to its hot, humid climate and well-developed infrastructure. Cocoa is king, and it grows in all areas but the Mbam division. The largest plantations are those outside of Yaoundé and to a greater extent to the northwest between the Nyong and Sanaga Rivers. Other major cocoa centres include the Sanaga River valley near Nanga Eboko and the regions around the towns of Akonolinga, Obala, and Saa. Some of these plantations are owned by peasant populations of Bassa and Ewondo, and SODECAO (Cocoa Development Company) is a major owner. The Centre is also home to Cameroon's only sugar-cane plantations, located at Mbandjock. SOSUCAM (Société Sucrerie du Cameroun) is the largest company in the region with 40 km2. Peasant sugar plantations also operate in the area. A variety of other crops make up the rest of the plantation economy. Rice cultivation occurs along the Sanaga River valley in fields owned by SARIOECOO. Coffee is another important crop, grown in