WASHINGTON

OVER the last decade, as populations have grown, capital has flowed across borders and crop yields have leveled off, food-importing nations and private investors have been securing land abroad to use for agriculture. Poor governments have embraced these deals, but their people are in danger of losing their patrimony, not to mention their sources of food.

According to Oxfam, land equivalent to eight times the size of Britain was sold or leased worldwide in the last 10 years. In northern Mozambique, a Brazilian-Japanese venture plans to farm more than 54,000 square miles — an area comparable to Pennsylvania and New Jersey combined — for food exports. In 2009, a Libyan firm leased 386 square miles of land from Mali without consulting local communities that had long used it. In the Philippines, the government is so enthusiastic to promote agribusiness that it lets foreigners register partnerships with local investors as domestic corporations.

The commoditization of global agriculture has aggravated the destabilizing effects of these large-scale land grabs. Investors typically promise to create local jobs and say that better farming technologies will produce higher crop yields and improve food security.

However, few of these benefits materialize. For example, as The Economist reported, a Swiss company promised local farmers 2,000 new jobs when it acquired a 50-year lease to grow biofuel crops on 154 square miles in Makeni, Sierra Leone; in the first three years, it produced only 50.