All the following are forms of subsistence farming in west Africa except

Subsistence farming refers to a type of agriculture where farmers grow crops and rear animals for their own consumption rather than for sale. Rotational bush farming, permanent cultivation, and mixed farming are all forms of subsistence farming commonly practiced in West Africa. In rotational bush farming, farmers clear a section of the bush, cultivate it for a few years, and then move to another section while the former regenerates. Permanent cultivation involves cultivating a piece of land continuously without allowing it to regenerate or fallow. Mixed farming involves growing different crops and rearing animals in the same field to maximize yield and reduce risk. Plantation agriculture, on the other hand, is not a form of subsistence farming. It involves the large-scale cultivation of cash crops such as cocoa, coffee, rubber, and palm oil for export to other countries. Plantation agriculture requires large tracts of land, specialized equipment, and a ready market for the crops, which makes it difficult for subsistence farmers to engage in. Therefore, the correct answer is plantation agriculture.