I do not know if this is too late, but a major problem is that many states with inadequate institutional capacities relating to effective land management do make overestimates on their available land. I have done a study on Tanzania, that can be found here: http://www.academicjournals.org/jene/PDF/Pdf2010/March/Haugen.pdf
A brief comment to the document: It lacks references to human rights impact and the due dilligence requierement for companies, as outlined in the UN Guiding Principles for Business and Human Rights (A/HRC/17/31), as well as the two standards by the UN Special Rapporteur on the right to food (A/HRC/19/59/Add.5, Appendix, Guiding principles on human rights impact assessments of trade and investment agreements and A/HRC/13/33/Add.2, Annex: Large-scale land acquisitions and leases: A set of minimum principles and measures to address the human rights challenge). The subsequent resolutions in the Human Rights Council did not endorse these Guiding Principles, unlike those on Business and Human Rights, but no states voted against the resolutions which welcomed the reports within which the two standards were found.
Related links and resources:
Biofuels and Food Security - A consultation by the HLPE to set the track of its study
Committee on World Food Security (CFS)
High Level Panel of Experts (HLPE)
The High Level Panel of Experts on Food Security and Nutrition (HLPE) Key Elements