The Revolution was a technological success.

The Revolution was a technological success.

"Before the 1960s, the population of India was multiplying like rats in a barn," said Jagjit Singh Hara, "but we didn't have the grain to feed them. After the Green Revolution, we doubled our yield and now we have proved that India can feed the world".

But the process has limits and they may have been reached. Population, on the other hand, has continued to rise in poor parts of the world.

The graph, compiled for the BBC by the UN Food and Agriculture Organization, shows that while yield per hectare has increased, the amount of land used for the major staple grains has remained fairly constant; this is because the amount of good farmland is finite.