Up to 30 million hectares (75 million acres) of land is lost to the new pressures and Olivier De Schutter, UN special rapporteur on the right to food, said 500 million small farmers suffer from hunger partly because "their right to land is under attack."
"As rural populations grow and competition with large industrial units increases, the plots cultivated by smallholders are shrinking year after year. Farmers are often relegated to soils that are arid, hilly or without irrigation," the envoy told the UN General Assembly.
He gave the example of India where the average landholding fell from 2.6 hectares in 1960 to 1.4 hectares in 2000 and is still shrinking. In eastern and southern Africa, the amount of cultivated land per capita declined by half over the past generation.
He said farmers, small holders and fishermen who lose their water access are all suffering and warned of "an explosive cocktail" brewing as foreign investors also compete for large areas of land for agriculture.
According to the expert, between five and 10 million hectares of farm land are lost each year because of severe degradation and another 19.5 million hectares to industrial use and urbanization.