While it is true that the vast majority of farmland investments in Africa are those of foreign entities, this is not always the case as an interesting piece in the WSJ makes clear:
[South African farmers] are scrambling to get on board an ambitious venture to reclaim farmland in Congo's interior and help relieve that country of a reliance on food imports. Already some 70 farmers have booked a Congo tour and more than 3,000 have expressed interest, said Agri-SA, the South African farming group organizing the venture.... According to a draft memorandum of understanding, Congo is willing to sign long-term leases and provide tax breaks and waivers on duties of imported supplies for approved projects. The South Africans in turn would build infrastructure, employ locals and instruct them in modern farming techniques. People familiar with the matter say the initial focus will be on restarting state-owned farms abandoned in 1992.... South African commercial farmers, mostly the descendants of Dutch and French pioneers who began settling the continent's southern tip centuries ago, are renowned for their ability to coax food out of African soil. Eager for their expertise and capital, African countries from Ghana to Nigeria have offered them incentives to set up shop. South African farmers have turned Mozambique into a banana powerhouse. Zambia became self-sufficient in maize after welcoming farmers from Zimbabwe and from South Africa.
As with foreign (i.e. non African) land investments/grabs, such programs are equally controversial, as they raise the very same issues of land tenure, colonialism, and eviction as do those by China, the United States, Saudi Arabia or any other countries. According to the contract governing the investment, South African farmers will enjoy a five-year holiday on corporate tax and the dismantling of taxes on the import of agricultural inputs such as seeds, fertilizer and machines. The farmers will be allowed to take all their profits out of the country and are under no obligation to sell their output on the domestic market. Oh dear.