New research on the global rush for agricultural land shows small-scale farmers increasingly at risk as land deals ignore local tenure rights.

Fresh evidence from Africa, Asia, Latin America and the former Soviet Union was presented last week at an international conference on "global land grabbing" convened by the Land Deal Politics Initiative and hosted by the Future Agricultures Consortium at the Institute of Development Studies, where researchers revealed documentation of land deals amounting to over 80m hectares – almost twice what was previously estimated.

The stakes are high for displaced small farmers, women and children, as well as national governments where land is being leased in large amounts. With land deals accelerating, particularly in Africa, it is essential that the fine print of such deals is subject to careful scrutiny, and that transparent and accountable governance mechanisms are put in place. And securing land rights is central to ensuring equitable agricultural development.

The rush to acquire land is driven by four factors: food price volatility and unreliable markets; the energy crisis and interest in agro-energy/biofuels; the global financial crisis; and a new market for carbon trading. Proponents of these deals say they are competitive, that they economise on labour, and that they produce food for export at prices low enough for poor consumers. But, as research from Cambodia to Cameroon to Colombia shows, the social and environmental costs of such deals are rarely taken into account.

"Small-scale family agriculture, on which most of the world's rural poor still depend, is threatened by large-scale plantations, export-led agriculture and the production not of food but commodities," said Olivier de Schutter, the UN rapporteur on the right to food, in his opening speech at the conference.

Policies that can curb the power of investors while securing rights for farmers must precede land deal negotiations. "The establishment of regulations and norms at multilateral levels is critical," said Ruth Hall of the Institute for Poverty, Land and Agrarian Studies in South Africa. "Small-scale farmers need national level regulations and institutions – the African Union's Land Policy Guidelines can help in this regard."

These policies must also deliver on human rights, said Sofía Monsalve from Fian International, as "forced evictions, the foreclosure of land, the denial of information about deals and the prevention of local participation in political decisions" violate land users human rights.

Last week's conference highlighted ways to increase the options of smallholder farmers. One strategy is to reorient agricultural investment away from land deals for large plantations or estates and towards highly productive and efficient small-scale family agriculture and markets, supported by stronger farmer voices.

Land grabs, either through economic or physical means, are, as Teo Ballvé from University of California, Berkeley put it, actually the "last step in a long chain of violent events" perpetrated against small farmers and pastoralists. The commodification and privatisation of land and the dispossession of farmers and herders is seldom taken into account in the boardrooms of corporations or in high-level meetings with governments.

Yet, some researchers at the conference argued that with the right international regulatory mechanisms, national government commitment to land rights, and stronger farmer voices holding governments and investors to account, there are ways that local food security and responsible land deals can coexist.

However, this will only happen if the deals are effectively negotiated; something that rarely happens today. Mahnaz Malik from the International Institute for Sustainable Development pointed out that "the fine print – no matter how boring – has major implications". This applies to specific land deal contracts, but also wider investment treaties. For example, certain clauses are highly restrictive, meaning that states are locked in to particular agreements over long periods. New laws to protect the environment or labour rights, for instance, cannot be implemented, as they may be subject to disputes and prohibitive compensation payments.

Bilateral treaties meant to attract much-needed investment to developing countries are particularly problematic, Malik argued. Globally, there are over 3,000 of these treaties across 183 counties, with many emerging from European countries, including Germany, Netherlands and the UK. These treaties allow private individuals or companies to bring claims against governments in international tribunals, where the scales are balanced very much in favour of the investor. By contrast, the rights of landholders affected by land deals are currently governed only by voluntary agreements and overarching principles, with no legally binding requirements.

Governments and communities must negotiate land deals with extreme caution. The track record to date has been poor, and while investment is critical for agriculture, the rush into long-term land leases is a dramatic step with numerous risks and often substantial costs.

• Jun Borras is a fellow at the Transnational Institute and editor-in-chief of the Journal of Peasant Studies

• Ian Scoones is a research fellow at the Institute of Development Studies

• David Hughes is a communication and networking officer at the Future Agricultures Consortium